Smith-Lemli-Opitz syndrome (SLOS) is a congenital multiple-anomaly / cognitive impairment syndrome caused by an abnormality in cholesterol metabolism resulting from deficiency of the enzyme 7-dehydrocholesterol (7-DHC) reductase. It is characterized by prenatal and postnatal growth restriction, microcephaly, moderate-to-severe intellectual disability, and multiple major and minor malformations. The malformations include distinctive facial features, cleft palate, cardiac defects, underdeveloped external genitalia in males, postaxial polydactyly, and 2-3 syndactyly of the toes. The clinical spectrum is wide; individuals with normal development and only minor malformations have been described.

Thrombocytopenia absent radius (TAR) syndrome is characterized by bilateral absence of the radii with the presence of both thumbs, and thrombocytopenia that is generally transient. Thrombocytopenia may be congenital or may develop within the first few weeks to months of life; in general, thrombocytopenic episodes decrease with age. Cow's milk allergy is common and can be associated with exacerbation of thrombocytopenia. Other anomalies of the skeleton (upper and lower limbs, ribs, and vertebrae), heart, and genitourinary system (renal anomalies and agenesis of uterus, cervix, and upper part of the vagina) can occur.

Congenital absence/hypoplasia of fingers excluding thumb, unilateral is a rare, non-syndromic, terminal transverse limb reduction defect characterized by unilateral absence of the terminal portions of digits 2 to 5, with a mildly hypoplastic thumb and small nail remnants on the digital stumps. Metacarpal bones may be variably reduced.

Fryns syndrome is characterized by diaphragmatic defects (diaphragmatic hernia, eventration, hypoplasia, or agenesis); characteristic facial appearance (coarse facies, wide-set eyes, a wide and depressed nasal bridge with a broad nasal tip, long philtrum, low-set and anomalous ears, tented vermilion of the upper lip, wide mouth, and a small jaw); short distal phalanges of the fingers and toes (the nails may also be small); pulmonary hypoplasia; and associated anomalies (polyhydramnios, cloudy corneas and/or microphthalmia, orofacial clefting, renal dysplasia / renal cortical cysts, and/or malformations involving the brain, cardiovascular system, gastrointestinal system, and/or genitalia). Survival beyond the neonatal period is rare. Data on postnatal growth and psychomotor development are limited; however, severe developmental delay and intellectual disability are common.

Miller syndrome, or postaxial acrofacial dysostosis, is a rare autosomal recessive disorder characterized clinically by severe micrognathia, cleft lip and/or palate, hypoplasia or aplasia of the postaxial elements of the limbs, coloboma of the eyelids, and supernumerary nipples (summary by Ng et al., 2010).

CHD7 disorder encompasses the entire phenotypic spectrum of heterozygous CHD7 pathogenic variants that includes CHARGE syndrome as well as subsets of features that comprise the CHARGE syndrome phenotype. The mnemonic CHARGE syndrome, introduced in the premolecular era, stands for coloboma, heart defect, choanal atresia, retarded growth and development, genital hypoplasia, ear anomalies (including deafness). Following the identification of the genetic cause of CHD7 disorder, the phenotypic spectrum expanded to include cranial nerve anomalies, vestibular defects, cleft lip and/or palate, hypothyroidism, tracheoesophageal anomalies, brain anomalies, seizures, and renal anomalies. Life expectancy highly depends on the severity of manifestations; mortality can be high in the first few years when severe birth defects (particularly complex heart defects) are present and often complicated by airway and feeding issues. In childhood, adolescence, and adulthood, decreased life expectancy is likely related to a combination of residual heart defects, infections, aspiration or choking, respiratory issues including obstructive and central apnea, and possibly seizures. Despite these complications, the life expectancy for many individuals can be normal.

The branchiooculofacial syndrome (BOFS) is characterized by: branchial (cervical or infra- or supra-auricular) skin defects that range from barely perceptible thin skin or hair patch to erythematous "hemangiomatous" lesions to large weeping erosions; ocular anomalies that can include microphthalmia, anophthalmia, coloboma, and nasolacrimal duct stenosis/atresia; and facial anomalies that can include ocular hypertelorism or telecanthus, broad nasal tip, upslanted palpebral fissures, cleft lip or prominent philtral pillars that give the appearance of a repaired cleft lip (formerly called "pseudocleft lip") with or without cleft palate, upper lip pits, and lower facial weakness (asymmetric crying face or partial 7th cranial nerve weakness). Malformed and prominent pinnae and hearing loss from inner ear and/or petrous bone anomalies are common. Intellect is usually normal.

Osteoglophonic dysplasia (OGD) is characterized by rhizomelic dwarfism, nonossifying bone lesions, craniosynostosis, prominent supraorbital ridge, and depressed nasal bridge (summary by White et al., 2005).

The pseudoaminopterin syndrome (aminopterin syndrome sine aminopterin; ASSA) is a multiple congenital anomaly disorder characterized by ossification defects of the skull, dysmorphic facial features, delayed development, and variable limb defects. The clinical features resemble the embryopathy caused by maternal treatment with the folic acid antagonist aminopterin, which has been recognized since 1952 (Thiersch, 1952) when aminopterin was used as an abortifacient. The characteristic phenotype of the children who survived infancy after having been exposed to aminopterin or its methyl derivative, methotrexate, in early pregnancy included a very unusual facies, skull anomalies, and skeletal defects (summary by Fraser et al., 1987).

An extremely rare syndrome with characteristics of facial dysmorphism, severe intellectual deficiency, cardiac and intestinal anomalies, and growth retardation. Only four cases have been reported in the literature, in three unrelated families. Dysmorphic features include bilateral cleft lip and palate, bulbous nasal tip and eye anomalies. The condition seems to be inherited as an autosomal recessive trait.

Spondyloperipheral dysplasia is a disorder that impairs bone growth. This condition is characterized by flattened bones of the spine (platyspondyly) and unusually short fingers and toes (brachydactyly), with the exception of the first (big) toes. Other skeletal abnormalities associated with spondyloperipheral dysplasia include short stature, shortened long bones of the arms and legs, exaggerated curvature of the lower back (lordosis), and an inward- and upward-turning foot (clubfoot). Additionally, some affected individuals have nearsightedness (myopia), hearing loss, and intellectual disability.

IVIC syndrome (IVIC) is an autosomal dominant disorder characterized by upper limb anomalies (radial ray defects, carpal bone fusion), extraocular motor disturbances, and congenital bilateral nonprogressive mixed hearing loss. More variable features include heart involvement, mild thrombocytopenia and leukocytosis (before age 50), shoulder girdle hypoplasia, imperforate anus, kidney malrotation, and rectovaginal fistula (summary by Paradisi and Arias, 2007).

SALL4-related disorders include Duane-radial ray syndrome (DRRS, Okihiro syndrome), acro-renal-ocular syndrome (AROS), and SALL4-related Holt-Oram syndrome (HOS) – three phenotypes previously thought to be distinct entities. DRRS is characterized by uni- or bilateral Duane anomaly and radial ray malformation that can include thenar hypoplasia and/or hypoplasia or aplasia of the thumbs, hypoplasia or aplasia of the radii, shortening and radial deviation of the forearms, triphalangeal thumbs, and duplication of the thumb (preaxial polydactyly). AROS is characterized by radial ray malformations, renal abnormalities (mild malrotation, ectopia, horseshoe kidney, renal hypoplasia, vesicoureteral reflux, bladder diverticula), ocular coloboma, and Duane anomaly. Rarely, pathogenic variants in SALL4 may cause clinically typical HOS (i.e., radial ray malformations and cardiac malformations without additional features).

Leri pleonosteosis is an autosomal dominant skeletal disorder characterized by flexion contractures of the interphalangeal joints, limited movement of multiple joints, and short, broad metacarpals, metatarsals, and phalanges. Additional features may include chronic joint pain, short stature, bony overgrowths, spinal cord compression, scleroderma-like skin changes, and blepharophimosis. The clinical features overlap with several other musculoskeletal conditions, including Myhre syndrome (MYHRS; 139210) and geleophysic dysplasia (GPHYSD1; 231050) (summary by Banka et al., 2015).

Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA.

Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA.

Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA.

Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA.

Hirschsprung disease-type D brachydactyly syndrome is characterized by Hirschsprung disease and absence or hypoplasia of the nails and distal phalanges of the thumbs and great toes (type D brachydactyly). It has been described in four males from one family (two brothers and two maternal uncles). Transmission appears to be X-linked recessive but autosomal dominant inheritance with incomplete penetrance in females can not be ruled out.

The X-linked otopalatodigital (X-OPD) spectrum disorders, characterized primarily by skeletal dysplasia, include the following: Otopalatodigital syndrome type 1 (OPD1). Otopalatodigital syndrome type 2 (OPD2). Frontometaphyseal dysplasia type 1 (FMD1). Melnick-Needles syndrome (MNS). Terminal osseous dysplasia with pigmentary skin defects (TODPD). In OPD1, most manifestations are present at birth; females can present with severity similar to affected males, although some have only mild manifestations. In OPD2, females are less severely affected than related affected males. Most males with OPD2 die during the first year of life, usually from thoracic hypoplasia resulting in pulmonary insufficiency. Males who live beyond the first year of life are usually developmentally delayed and require respiratory support and assistance with feeding. In FMD1, females are less severely affected than related affected males. Males do not experience a progressive skeletal dysplasia but may have joint contractures and hand and foot malformations. Progressive scoliosis is observed in both affected males and females. In MNS, wide phenotypic variability is observed; some individuals are diagnosed in adulthood, while others require respiratory support and have reduced longevity. MNS in males results in perinatal lethality in all recorded cases. TODPD, seen only in females, is characterized by a skeletal dysplasia that is most prominent in the digits, pigmentary defects of the skin, and recurrent digital fibromata.

A rare multiple congenital anomalies syndrome characterized by upper limb defects (hypoplastic thumb with hypoplasia of the metacarpal bone and phalanges and delayed bone maturation), developmental delay, central hearing loss, unilateral poorly developed antihelix, bilateral choroid coloboma and growth retardation.

Patients with Richieri-Costa-Pereira syndrome display a pattern of anomalies consisting of microstomia, micrognathia, abnormal fusion of the mandible, cleft palate/Robin sequence, absence of lower central incisors, minor ear anomalies, hypoplastic first ray, abnormal tibiae, hypoplastic halluces, and clubfeet. Learning disability is also a common finding (summary by Favaro et al., 2011).

Bartsocas-Papas syndrome-1 (BPS1) is an autosomal recessive disorder characterized by multiple popliteal pterygia, ankyloblepharon, filiform bands between the jaws, cleft lip and palate, and syndactyly. Early lethality is common, although survival into childhood and beyond has been reported (summary by Mitchell et al., 2012). Genetic Heterogeneity of Bartsocas-Papas Syndrome Bartsocas-Papas syndrome-2 (BPS2) is caused by mutation in the CHUK gene (600664). A less severe form of popliteal pterygium syndrome (PPS; 119500) is caused by mutation in the IRF6 gene (607199).

Keutel syndrome (KTLS) is an autosomal recessive disorder characterized by multiple peripheral pulmonary stenoses, brachytelephalangy, inner ear deafness, and abnormal cartilage ossification or calcification (summary by Khosroshahi et al., 2014).

Lethal faciocardiomelic dysplasia is an extremely rare polymalformative syndrome. It was described only once, in 1975, in 3 affected males in a sibship of 13, from second-cousin parents. Patients were all of low birth weight, had microretrognathia, microstomia, and microglossia, hypoplasia of the radius and ulna with radial deviation of the hands, simian creases and hypoplasia of fingers I and V, hypoplasia of the fibula and tibia with talipes and wide space between toes I and II, and severe malformation of the left heart which may have been responsible for death of all 3 in the first week or so of life.

Yunis-Varon syndrome (YVS) is a severe autosomal recessive disorder characterized by skeletal defects, including cleidocranial dysplasia and digital anomalies, and severe neurologic involvement with neuronal loss. Enlarged cytoplasmic vacuoles are found in neurons, muscle, and cartilage. The disorder is usually lethal in infancy (summary by Campeau et al., 2013).

Microcephalic osteodysplastic primordial dwarfism type I is a severe autosomal recessive skeletal dysplasia characterized by dwarfism, microcephaly, and neurologic abnormalities, including mental retardation, brain malformations, and ocular/auditory sensory deficits. Patients often die in early childhood (summary by Pierce and Morse, 2012).

Thumb deformity-alopecia-pigmentation anomaly syndrome is a rare, genetic, congenital limb malformation syndrome characterized by short stature, sparse scalp hair, hypoplastic, proximally-placed thumbs, and skin hyperpigmentation with areas of 'raindrop' depigmentation. Presence of a single, upper central incisor has also been reported. There have been no further descriptions in the literature since 1988.

A rare congenital limb malformation characterized the association of hallux varus with short thumbs and first toes (involving the metacarpals, metatarsals, and distal phalanges; the proximal and middle phalanges are of normal length) and abduction of the affected digits. Intellectual deficit was observed in all reported individuals. There have been no further reports since 1994.

Acropectorovertebral dysgenesis, or F syndrome, is an autosomal dominant skeletal dysplasia characterized by carpal and tarsal synostoses, syndactyly between the first and second fingers, hypodactyly and polydactyly of feet, and abnormalities of the sternum and spine (summary by Thiele et al., 2004).

An extremely rare syndrome with characteristics of hypoplastic thumbs and halluces, fifth finger brachydactyly, postaxial polydactyly of the hands, short or uniphalangeal second toes with absent nails and hypospadias. It has been described in a father and his son and daughter. The affected patients have normal mental development. Except for postaxial polydactyly of the hands and uniphalangeal second toes with absent nails, features are in common with hand-foot-genital syndrome caused by mutations in the HOXA13 gene. In all three affected individuals, two different sequence alterations were identified in HOXA13 gene: a de novo missense mutation and a deletion in the promoter region of the gene, inherited from an unaffected parent, which may contribute to the phenotype in the affected individuals. The condition is inherited in an autosomal dominant manner.

Wolf-Hirschhorn syndrome is a congenital malformation syndrome characterized by pre- and postnatal growth deficiency, developmental disability of variable degree, characteristic craniofacial features ('Greek warrior helmet' appearance of the nose, high forehead, prominent glabella, hypertelorism, high-arched eyebrows, protruding eyes, epicanthal folds, short philtrum, distinct mouth with downturned corners, and micrognathia), and a seizure disorder (Battaglia et al., 2008).

Diamond-Blackfan anemia (DBA) is characterized by a profound normochromic and usually macrocytic anemia with normal leukocytes and platelets, congenital malformations in up to 50%, and growth deficiency in 30% of affected individuals. The hematologic complications occur in 90% of affected individuals during the first year of life. The phenotypic spectrum ranges from a mild form (e.g., mild anemia or no anemia with only subtle erythroid abnormalities, physical malformations without anemia) to a severe form of fetal anemia resulting in nonimmune hydrops fetalis. DBA is associated with an increased risk for acute myelogenous leukemia (AML), myelodysplastic syndrome (MDS), and solid tumors including osteogenic sarcoma.

Diamond-Blackfan anemia (DBA) is characterized by a profound normochromic and usually macrocytic anemia with normal leukocytes and platelets, congenital malformations in up to 50%, and growth deficiency in 30% of affected individuals. The hematologic complications occur in 90% of affected individuals during the first year of life. The phenotypic spectrum ranges from a mild form (e.g., mild anemia or no anemia with only subtle erythroid abnormalities, physical malformations without anemia) to a severe form of fetal anemia resulting in nonimmune hydrops fetalis. DBA is associated with an increased risk for acute myelogenous leukemia (AML), myelodysplastic syndrome (MDS), and solid tumors including osteogenic sarcoma.

Acromesomelic dysplasia-2C (AMD2C) is characterized by skeletal abnormalities restricted to the limbs; the craniofacial skeleton and axial skeletal structures are normal. The severity of the long bone shortening progresses in a proximal to distal direction. The hands and feet are most severely affected, but the distal phalanges are relative normal. Affected individuals have joint dislocations but the number of joints involved is not constant (summary by Thomas et al., 1996). For a discussion of genetic heterogeneity of acromesomelic dysplasia, see AMD1 (602875).

An extremely rare syndrome with characteristics of radial ray hypoplasia, choanal atresia and convergent strabismus. It has been reported in a father and his two daughters. The radial ray involvement varies from absent radius, first metacarpal and thumb to hypoplastic thumb or triphalangeal thumb. Transmitted as an autosomal dominant trait.

Diamond-Blackfan anemia (DBA) is characterized by a profound normochromic and usually macrocytic anemia with normal leukocytes and platelets, congenital malformations in up to 50%, and growth deficiency in 30% of affected individuals. The hematologic complications occur in 90% of affected individuals during the first year of life. The phenotypic spectrum ranges from a mild form (e.g., mild anemia or no anemia with only subtle erythroid abnormalities, physical malformations without anemia) to a severe form of fetal anemia resulting in nonimmune hydrops fetalis. DBA is associated with an increased risk for acute myelogenous leukemia (AML), myelodysplastic syndrome (MDS), and solid tumors including osteogenic sarcoma.

Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA.

16p13.3 microduplication syndrome is a rare chromosomal anomaly syndrome resulting from a partial duplication of the short arm of chromosome 16 and manifesting with a variable phenotype which is mostly characterized by: mild to moderate intellectual deficit and developmental delay (particularly speech), normal growth, short, proximally implanted thumbs and other hand and feet malformations (such as camptodactyly, syndactyly, club feet), mild arthrogryposis and characteristic facies (upslanting, narrow palpebral fissures, hypertelorism, mid face hypoplasia, bulbous nasal tip and low set ears). Other reported manifestations include cryptorchidism, inguinal hernia and behavioral problems.

A rare, genetic, chromosomal anomaly syndrome resulting from partial duplication of the long arm of chromosome 2 characterized by congenital pendular nystagmus associated with bilateral cutaneous syndactyly between the third and fourth fingers.

Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA.

Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA.

Feingold syndrome is an autosomal dominant disorder characterized by variable combinations of microcephaly, limb malformations, esophageal and duodenal atresias, and learning disability/mental retardation. Hand and foot abnormalities may include hypoplastic thumbs, clinodactyly of second and fifth fingers, syndactyly (characteristically between second and third and fourth and fifth toes), and shortened or absent middle phalanges. Cardiac and renal malformations, vertebral anomalies, and deafness have also been described in a minority of patients (summary by Teszas et al., 2006). For a discussion of genetic heterogeneity of Feingold syndrome, see FGLDS1 (164280).

Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA.

Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA.

Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA.

Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA.

A rare genetic congenital limb malformation syndrome with characteristics of a unique combination of bilateral, symmetrical camptodactyly and clinodactyly of fifth fingers, mesoaxial camptodactyly of toes and ulnar deviation of third fingers. Additional variable manifestations include bifid toes and severe syndactyly or synpolydactyly involving all digits of hands and feet.

Patients with SSOAD exhibit a broad phenotypic spectrum involving short stature associated with advanced bone maturation and early-onset osteoarthritis (OA), as well as mild dysmorphic features consisting of midface hypoplasia, brachydactyly, broad great toes, and lumbar lordosis. Other features include intervertebral disc disease and osteochondritis dissecans, which is characterized by separation of articular cartilage and subchondral bone from the articular surface. Phenotypes are highly variable even among patients within the same family, and there are no apparent genotype-phenotype correlations (Dateki et al., 2017). The term 'dissecans' comes from 'dis' meaning 'from' and 'secare' meaning 'cut off,' and is not to be confused with 'desiccans' derived from 'desiccare' meaning to 'dry up.' Dissecans refers to the appearance of part of the bone having been cut away.

MED12-related disorders include the phenotypes of FG syndrome type 1 (FGS1), Lujan syndrome (LS), X-linked Ohdo syndrome (XLOS), Hardikar syndrome (HS), and nonspecific intellectual disability (NSID). FGS1 and LS share the clinical findings of cognitive impairment, hypotonia, and abnormalities of the corpus callosum. FGS1 is further characterized by absolute or relative macrocephaly, tall forehead, downslanted palpebral fissures, small and simple ears, constipation and/or anal anomalies, broad thumbs and halluces, and characteristic behavior. LS is further characterized by large head, tall thin body habitus, long thin face, prominent nasal bridge, high narrow palate, and short philtrum. Carrier females in families with FGS1 and LS are typically unaffected. XLOS is characterized by intellectual disability, blepharophimosis, and facial coarsening. HS has been described in females with cleft lip and/or cleft palate, biliary and liver anomalies, intestinal malrotation, pigmentary retinopathy, and coarctation of the aorta. Developmental and cognitive concerns have not been reported in females with HS. Pathogenic variants in MED12 have been reported in an increasing number of males and females with NSID, with affected individuals often having clinical features identified in other MED12-related disorders.

Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA.

Palatal anomalies-widely spaced teeth-facial dysmorphism-developmental delay syndrome is a rare, genetic multiple congenital anomalies/dysmorphic syndrome characterized by global developmental delay, axial hypotonia, palate abnormalities (including cleft palate and/or high and narrow palate), dysmorphic facial features (including prominent forehead, hypertelorism, downslanting palpebral fissures, wide nasal bridge, thin lips and widely spaced teeth), and short stature. Additional manifestations may include digital anomalies (such as brachydactyly, clinodactyly, and hypoplastic toenails), a single palmar crease, lower limb hypertonia, joint hypermobility, as well as ocular and urogenital anomalies.

A rare genetic neurological disorder with characteristics of childhood-onset severe myoclonic and tonic-clonic seizures and early-onset ataxia leading to severe gait disturbances associated with normal to slightly diminished cognition. Scoliosis, diffuse muscle atrophy and subcutaneous fat loss, as well as developmental delay, may be associated. Brain MRI may reveal complete agenesis of the corpus callosum, ventriculomegaly, interhemispheric cysts and simplified gyration (frontally).

VATER is a mnemonically useful acronym for the nonrandom association of vertebral defects (V), anal atresia (A), tracheoesophageal fistula with esophageal atresia (TE), and radial or renal dysplasia (R). This combination of associated defects was pointed out by Quan and Smith (1972). Nearly all cases have been sporadic. VACTERL is an acronym for an expanded definition of the association that includes cardiac malformations (C) and limb anomalies (L). The VACTERL association is a spectrum of various combinations of its 6 components, which can be a manifestation of several recognized disorders rather than a distinct anatomic or etiologic entity (Khoury et al., 1983). Also see VATER/VACTERL association with hydrocephalus (VACTERL-H; 276950) and VACTERL with or without hydrocephalus (VACTERLX; 314390).

Witteveen-Kolk syndrome (WITKOS) is an autosomal dominant disorder with characteristic distinctive facial features, microcephaly, short stature, and mildly impaired intellectual development with delayed cognitive and motor development and subtle anomalies on MRI-brain imaging (summary by Balasubramanian et al., 2021).

Stankiewicz-Isidor syndrome (STISS) is a neurodevelopmental disorder characterized by delayed psychomotor development, intellectual disability, behavioral disorders, mild craniofacial anomalies, and variable congenital defects of the cardiac and/or urogenital systems (summary by Kury et al., 2017).

Feingold syndrome 1 (referred to as FS1 in this GeneReview) is characterized by digital anomalies (shortening of the 2nd and 5th middle phalanx of the hand, clinodactyly of the 5th finger, syndactyly of toes 2-3 and/or 4-5, thumb hypoplasia), microcephaly, facial dysmorphism (short palpebral fissures and micrognathia), gastrointestinal atresias (primarily esophageal and/or duodenal), and mild-to-moderate learning disability.

Rubinstein-Taybi syndrome (RSTS) is characterized by distinctive facial features, broad and often angulated thumbs and halluces, short stature, and moderate-to-severe intellectual disability. The characteristic craniofacial features are downslanted palpebral fissures, low-hanging columella, high palate, grimacing smile, and talon cusps. Prenatal growth is often normal, then height, weight, and head circumference percentiles rapidly drop in the first few months of life. Short stature is typical in adulthood. Obesity may develop in childhood or adolescence. Average IQ ranges between 35 and 50; however, developmental outcome varies considerably. Some individuals with EP300-RSTS have normal intellect. Additional features include ocular abnormalities, hearing loss, respiratory difficulties, congenital heart defects, renal abnormalities, cryptorchidism, feeding problems, recurrent infections, and severe constipation.

Osteochondrodysplasia, brachydactyly, and overlapping malformed digits (OCBMD) is characterized by bilateral symmetric skeletal defects that primarily affect the limbs. Affected individuals have mild short stature due to shortening of the lower leg bones, as well as hand and foot malformations, predominantly brachydactyly and overlapping digits. Other skeletal defects include scoliosis, dislocated patellae and fibulae, and pectus excavatum (Shabbir et al., 2018).

Rothmund-Thomson syndrome (RTS) is characterized by a rash that progresses to poikiloderma; sparse hair, eyelashes, and/or eyebrows; small size; skeletal and dental abnormalities; juvenile cataracts; and an increased risk for cancer, especially osteosarcoma. A variety of benign and malignant hematologic abnormalities have been reported in affected individuals. The rash of RTS typically develops between ages three and six months (occasionally as late as age two years) as erythema, swelling, and blistering on the face, subsequently spreading to the buttocks and extremities. The rash evolves over months to years into the chronic pattern of reticulated hypo- and hyperpigmentation, telangiectasias, and punctate atrophy (collectively known as poikiloderma) that persist throughout life. Hyperkeratotic lesions occur in approximately one third of individuals. Skeletal abnormalities can include radial ray defects, ulnar defects, absent or hypoplastic patella, and osteopenia.

Rhizomelic limb shortening with dysmorphic features (RLSDF) is characterized by rhizomelic shortening of the extremities, predominantly of the upper limbs, and variable dysmorphic features, including macrocephaly, prominent forehead, hypertelorism, depressed or broad nasal bridge, and micrognathia. Hearing loss has also been observed (Sajan et al., 2019; Pagnamenta et al., 2023).

Chromosome 13q33-q34 deletion syndrome is associated with developmental delay and/or impaired intellectual development, facial dysmorphism, and an increased risk for epilepsy, cardiac defects and additional anatomic anomalies (summary by Sagi-Dain et al., 2019).

Coffin-Siris syndrome-12 (CSS12) is a neurodevelopmental disorder characterized by global developmental delay with variably impaired intellectual development, speech and language delay, and behavioral abnormalities, such as autism or hyperactivity. Affected individuals may have hypotonia and poor feeding in infancy. There are variable dysmorphic facial features, although most patients do not have the classic hypoplastic fifth digit/nail abnormalities that are often observed in other forms of CSS (Barish et al., 2020). For a general phenotypic description and a discussion of genetic heterogeneity of Coffin-Siris syndrome, see CSS1 (135900).

DEGCAGS syndrome is an autosomal recessive syndromic neurodevelopmental disorder characterized by global developmental delay, coarse and dysmorphic facial features, and poor growth and feeding apparent from infancy. Affected individuals have variable systemic manifestations often with significant structural defects of the cardiovascular, genitourinary, gastrointestinal, and/or skeletal systems. Additional features may include sensorineural hearing loss, hypotonia, anemia or pancytopenia, and immunodeficiency with recurrent infections. Death in childhood may occur (summary by Bertoli-Avella et al., 2021).

Neurodevelopmental-craniofacial syndrome with variable renal and cardiac abnormalities (NECRC) is an autosomal dominant disorder characterized by dysmorphic craniofacial features associated with mild developmental delay, mildly impaired intellectual development or learning difficulties, speech delay, and behavioral abnormalities. About half of patients have congenital anomalies of the kidney and urinary tract (CAKUT) and/or congenital cardiac defects, including septal defects (Connaughton et al., 2020).

Lacrimoauriculodentodigital syndrome-3 (LADD3) is a multiple congenital anomaly disorder characterized by aplasia, atresia or hypoplasia of the lacrimal and salivary systems, cup-shaped ears, hearing loss, and dental and digital anomalies (summary by Milunsky et al., 2006).

Lacrimoauriculodentodigital syndrome-1 (LADD1) is a multiple congenital anomaly disorder mainly affecting lacrimal glands and ducts, salivary glands and ducts, ears, teeth, and distal limb segments (summary by Rohmann et al., 2006). Genetic Heterogeneity of Lacrimoauriculodentodigital Syndrome LADD syndrome-2 (LADD2; 620192) is caused by mutation in the FGFR3 gene (134934) on chromosome 4p16, and LADD syndrome-3 (LADD3; 620193) is caused by mutation in the FGF10 gene, an FGFR ligand, on chromosome 5p12.

Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skeletal anomalies, with or without seizures (NEDFSS), is characterized by these features and global developmental delay with delayed or absent walking, moderate to severely impaired intellectual development, and poor or absent speech acquisition. Affected individuals may also have behavioral abnormalities. About half of patients develop various types of seizures that are usually well-controlled with medication. Rare patients are noted to have heat intolerance or insensitivity to pain (Lines et al., 2022).