Focal dermal hypoplasia is a multisystem disorder characterized primarily by involvement of the skin, skeletal system, eyes, and face. Skin manifestations present at birth include atrophic and hypoplastic areas of skin; cutis aplasia; fat nodules in the dermis manifesting as soft, yellow-pink cutaneous nodules; and pigmentary changes. Verrucoid papillomas of the skin and mucous membranes may appear later. The nails can be ridged, dysplastic, or hypoplastic; hair can be sparse or absent. Limb malformations include oligo-/syndactyly and split hand/foot. Developmental abnormalities of the eye can include anophthalmia/microphthalmia, iris and chorioretinal coloboma, and lacrimal duct abnormalities. Craniofacial findings can include facial asymmetry, notched alae nasi, cleft lip and palate, and pointed chin. Occasional findings include dental anomalies, abdominal wall defects, diaphragmatic hernia, and renal anomalies. Psychomotor development is usually normal; some individuals have cognitive impairment.

In its rare complete form, 'prune belly' syndrome comprises megacystis (massively enlarged bladder) with disorganized detrusor muscle, cryptorchidism, and thin abdominal musculature with overlying lax skin (summary by Weber et al., 2011).

Distal arthrogryposis type 1 is a disorder characterized by joint deformities (contractures) that restrict movement in the hands and feet. The term "arthrogryposis" comes from the Greek words for joint (arthro-) and crooked or hooked (gryposis). The characteristic features of this condition include permanently bent fingers and toes (camptodactyly), overlapping fingers, and a hand deformity in which all of the fingers are angled outward toward the fifth finger (ulnar deviation). Clubfoot, which is an inward- and upward-turning foot, is also commonly seen with distal arthrogryposis type 1. The specific hand and foot abnormalities vary among affected individuals. However, this condition typically does not cause any signs and symptoms affecting other parts of the body.

DA3, or Gordon syndrome, is distinguished from other distal arthrogryposes by short stature and cleft palate (summary by Bamshad et al., 2009). There are 2 syndromes with features overlapping those of DA3 that are also caused by heterozygous mutation in PIEZO2: distal arthrogryposis type 5 (DA5; 108145) and Marden-Walker syndrome (MWKS; 248700), which are distinguished by the presence of ocular abnormalities and mental retardation, respectively. McMillin et al. (2014) suggested that the 3 disorders may represent variable expressivity of the same condition. For a phenotypic description and a discussion of genetic heterogeneity of distal arthrogryposis, see DA1 (108120).

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).

The NSDHL-related disorders include: CHILD (congenital hemidysplasia with ichthyosiform nevus and limb defects) syndrome, an X-linked condition that is usually male lethal during gestation and thus predominantly affects females; and CK syndrome, an X-linked disorder that affects males. CHILD syndrome is characterized by unilateral distribution of ichthyosiform (yellow scaly) skin lesions and ipsilateral limb defects that range from shortening of the metacarpals and phalanges to absence of the entire limb. Intellect is usually normal. The ichthyosiform skin lesions are usually present at birth or in the first weeks of life; new lesions can develop in later life. Nail changes are also common. The heart, lung, and kidneys can also be involved. CK syndrome (named for the initials of the original proband) is characterized by mild to severe cognitive impairment and behavior problems (aggression, attention deficit hyperactivity disorder, and irritability). All affected males reported have developed seizures in infancy and have cerebral cortical malformations and microcephaly. All have distinctive facial features, a thin habitus, and relatively long, thin fingers and toes. Some have scoliosis and kyphosis. Strabismus is common. Optic atrophy is also reported.

Cerebrocostomandibular syndrome (CCMS) is characterized mainly by severe micrognathia, rib defects, and mental retardation. A spectrum of rib gap defects have been reported ranging from a few dorsal rib segments to complete absence of ossification. In about half of the 65 reported cases to date, there is cerebral involvement including mental retardation, microcephaly, and histologic anomalies. Both autosomal dominant and autosomal recessive forms of the disorder have been described (Zeevaert et al., 2009). See CDG2G (611209) for a cerebrocostomandibular-like syndrome.

Pallister-Killian syndrome (PKS) is a dysmorphic condition involving most organ systems, but is also characterized by a tissue-limited mosaicism; most fibroblasts have 47 chromosomes with an extra small metacentric chromosome, whereas the karyotype of lymphocytes is normal. The extra metacentric chromosome is an isochromosome for part of the short arm of chromosome 12: i(12)(p10) (Peltomaki et al., 1987; Warburton et al., 1987).

Classic Ehlers-Danlos syndrome (cEDS) is a connective tissue disorder characterized by skin hyperextensibility, atrophic scarring, and generalized joint hypermobility (GJH). The skin is soft and doughy to the touch, and hyperextensible, extending easily and snapping back after release (unlike lax, redundant skin, as in cutis laxa). The skin is fragile, as manifested by splitting of the dermis following relatively minor trauma, especially over pressure points (knees, elbows) and areas prone to trauma (shins, forehead, chin). Wound healing is poor, and stretching of scars after apparently successful primary wound healing is characteristic. Complications of joint hypermobility, such as dislocations of the shoulder, patella, digits, hip, radius, and clavicle, usually resolve spontaneously or are easily managed by the affected individual. Other features include hypotonia with delayed motor development, fatigue and muscle cramps, and easy bruising. Mitral valve prolapse can occur infrequently, but tends to be of little clinical consequence. Aortic root dilatation has been reported, appears to be more common in young individuals, and rarely progresses.

PLOD1-related kyphoscoliotic Ehlers-Danlos syndrome (kEDS) is an autosomal recessive generalized connective tissue disorder characterized by hypotonia, early-onset kyphoscoliosis, and generalized joint hypermobility in association with skin fragility and ocular abnormality. Intelligence is normal. Life span may be normal, but affected individuals are at risk for rupture of medium-sized arteries. Adults with severe kyphoscoliosis are at risk for complications from restrictive lung disease, recurrent pneumonia, and cardiac failure.

Brittle cornea syndrome (BCS) is characterized by blue sclerae, corneal rupture after minor trauma, keratoconus or keratoglobus, hyperelasticity of the skin, and hypermobility of the joints (Al-Hussain et al., 2004). It is classified as a form of Ehlers-Danlos syndrome (Malfait et al., 2017). Genetic Heterogeneity of Brittle Cornea Syndrome Brittle cornea syndrome-2 (BCS2; 614170) is caused by mutation in the PRDM5 gene (614161) on chromosome 4q27.

A rare genetic disease characterized by generalized joint laxity leading to recurrent dislocation of major joints, such as the hip (often with congenital hip dislocation), shoulder, elbow, or patella. Patients often experience muscle and joint pain (sometimes with effusion) and may develop degenerative joint changes at a relatively early age. Skin abnormalities are absent.

ATP6V0A2-related cutis laxa is characterized by generalized cutis laxa, findings associated with generalized connective tissue disorder, developmental delays, and a variety of neurologic findings including abnormality on brain MRI. At birth, hypotonia, overfolded skin, and distinctive facial features are present and enlarged fontanelles are often observed. During childhood, the characteristic facial features and thick or coarse hair may become quite pronounced. The skin findings decrease with age, although easy bruising and Ehlers-Danlos-like scars have been described in some. In most (not all) affected individuals, cortical and cerebellar malformations are observed on brain MRI. Nearly all affected individuals have developmental delays, seizures, and neurologic regression.

ATP6V0A2-related cutis laxa is characterized by generalized cutis laxa, findings associated with generalized connective tissue disorder, developmental delays, and a variety of neurologic findings including abnormality on brain MRI. At birth, hypotonia, overfolded skin, and distinctive facial features are present and enlarged fontanelles are often observed. During childhood, the characteristic facial features and thick or coarse hair may become quite pronounced. The skin findings decrease with age, although easy bruising and Ehlers-Danlos-like scars have been described in some. In most (not all) affected individuals, cortical and cerebellar malformations are observed on brain MRI. Nearly all affected individuals have developmental delays, seizures, and neurologic regression.

Congenital myopathy-1A (CMYP1A) with susceptibility to malignant hyperthermia is an autosomal dominant disorder of skeletal muscle characterized by muscle weakness primarily affecting the proximal muscles of the lower limbs beginning in infancy or early childhood, although later onset of symptoms has been reported. There is significant phenotypic variability, even within families, and the wide clinical diversity most likely depends on the severity of the RYR1 mutation. The disorder is static or slowly progressive; affected individuals typically show delayed motor development and usually achieve independent walking, although many have difficulty running or climbing stairs. Additional features often include mild facial weakness, joint laxity, shoulder girdle weakness, and skeletal manifestations, such as dislocation of the hips, foot deformities, scoliosis, and Achilles tendon contractures. Some patients present with orthopedic deformities. Serum creatine kinase is usually not elevated. Respiratory involvement is rare and there is no central nervous system or cardiac involvement. Patients with dominant mutations in the RYR1 gene are at risk for malignant hyperthermia and both disorders may segregate in the same family. Historically, patients with congenital myopathy due to RYR1 mutations were diagnosed based on the finding of pathologic central cores (central core disease; CCD) on muscle biopsy, which represent areas that lack oxidative enzymes and mitochondrial activity in type 1 muscle fibers. However, additional pathologic findings may also be observed, including cores and rods, central nuclei, fiber type disproportion, multiminicores, and uniform type 1 fibers. These histopathologic features are not always specific to RYR1 myopathy and often change over time (Quinlivan et al., 2003; Jungbluth et al., 2007; Klein et al., 2012; Ogasawara and Nishino, 2021). Some patients with RYR1 mutations have pathologic findings on muscle biopsy, but are clinically asymptomatic (Shuaib et al., 1987; Quane et al., 1993). Rare patients with a more severe phenotype have been found to carry a heterozygous mutation in the RYR1 gene inherited from an unaffected parent. However, in these cases, there is a possibility of recessive inheritance (CMYP1B; 255320) with either a missed second RYR1 mutation in trans or a genomic rearrangement on the other allele that is undetectable on routine genomic sequencing, since the RYR1 gene is very large and genetic analysis may be difficult (Klein et al., 2012). Genetic Heterogeneity of Congenital Myopathy See also CMYP1B (255320), caused by mutation in the RYR1 gene (180901) on chromosome 19q13; CMYP2A (161800), CMYP2B (620265), and CMYP2C (620278), caused by mutation in the ACTA1 gene (102610) on chromosome 1q42; CMYP3 (602771), caused by mutation in the SELENON gene (606210) on chromosome 1p36; CMYP4A (255310) and CMYP4B (609284), caused by mutation in the TPM3 gene (191030) on chromosome 1q21; CMYP5 (611705), caused by mutation in the TTN gene (188840) on chromosome 2q31; CMYP6 (605637), caused by mutation in the MYH2 gene (160740) on chromosome 17p13; CMYP7A (608358) and CMYP7B (255160), caused by mutation in the MYH7 gene (160760) on chromosome 14q11; CMYP8 (618654), caused by mutation in the ACTN2 gene (102573) on chromosome 1q43; CMYP9A (618822) and CMYP9B (618823), caused by mutation in the FXR1 gene (600819) on chromosome 3q28; CMYP10A (614399) and CMYP10B (620249), caused by mutation in the MEGF10 gene (612453) on chromosome 5q23; CMYP11 (619967), caused by mutation in the HACD1 gene (610467) on chromosome 10p12; CMYP12 (612540), caused by mutation in the CNTN1 gene (600016) on chromosome 12q12; CMYP13 (255995), caused by mutation in the STAC3 gene (615521) on chromosome 12q13; CMYP14 (618414), caused by mutation in the MYL1 gene (160780) on chromosome 2q34; CMYP15 (620161), caused by mutation in the TNNC2 gene (191039) on chromosome 20q13; CMYP16 (618524), caused by mutation in the MYBPC1 gene (160794) on chromosome 12q23; CMYP17 (618975), caused by mutation in the MYOD1 gene (159970) on chromosome 11p15; CMYP18 (620246), caused by mutation in the CACNA1S gene (114208) on chromosome 1q32; CMYP19 (618578), caused by mutation in the PAX7 gene (167410) on chromosome 1p36; CMYP20 (620310), caused by mutation in the RYR3 gene (180903) on chromosome 15q13; CMYP21 (620326), caused by mutation in the DNAJB4 gene (611327) on chromosome 1p31; CMYP22A (620351) and CMYP22B (620369), both caused by mutation in the SCN4A gene (603967) on chromosome 17q23; CMYP23 (609285), caused by mutation in the TPM2 gene (190990) on chromosome 9p13; and CMYP24 (617336), caused by mutation in the MYPN gene (608517) on chromosome 10q21.

Kabuki syndrome (KS) is characterized by typical facial features (long palpebral fissures with eversion of the lateral third of the lower eyelid; arched and broad eyebrows; short columella with depressed nasal tip; large, prominent, or cupped ears), minor skeletal anomalies, persistence of fetal fingertip pads, mild-to-moderate intellectual disability, and postnatal growth deficiency. Other findings may include: congenital heart defects, genitourinary anomalies, cleft lip and/or palate, gastrointestinal anomalies including anal atresia, ptosis and strabismus, and widely spaced teeth and hypodontia. Functional differences can include: increased susceptibility to infections and autoimmune disorders, seizures, endocrinologic abnormalities (including isolated premature thelarche in females), feeding problems, and hearing loss.

A rare neurologic disease typically characterized by the triad of eye, central nervous system and skin malformations, and often associated with an intellectual disability.

McKusick-Kaufman syndrome (MKS) is characterized by the combination of postaxial polydactyly (PAP), congenital heart disease (CHD), and hydrometrocolpos (HMC) in females and genital malformations in males (most commonly hypospadias, cryptorchidism, and chordee). HMC in infants usually presents as a large cystic abdominal mass arising out of the pelvis, caused by dilatation of the vagina and uterus as a result of the accumulation of cervical secretions from maternal estrogen stimulation. HMC can be caused by failure of the distal third of the vagina to develop (vaginal agenesis), a transverse vaginal membrane, or an imperforate hymen. PAP is the presence of additional digits on the ulnar side of the hand and the fibular side of the foot. A variety of congenital heart defects have been reported including atrioventricular canal, atrial septal defect, ventricular septal defect, or a complex congenital heart malformation.

Congenital dysplasia of the hip (CDH) is an abnormality of the seating of the femoral head in the acetabulum. Its severity ranges from mild instability of the femoral head with slight capsular laxity, through moderate lateral displacement of the femoral head, without loss of contact of the head with the acetabulum, up to complete dislocation of the femoral head from the acetabulum. It is one of the most common skeletal congenital anomalies (summary by Sollazzo et al., 2000). Acetabular dysplasia is an idiopathic, localized developmental dysplasia of the hip that is characterized by a shallow hip socket and decreased coverage of the femoral head. Its radiologic criteria include the center-edge angle of Wiberg, the Sharp angle, and the acetabular roof obliquity. Most patients with acetabular dysplasia develop osteoarthritis (165720) after midlife, and even mild acetabular dysplasia can cause hip osteoarthritis (summary by Mabuchi et al., 2006). CDH occurs as an isolated anomaly or with more general disorders represented by several syndromes and with chromosomal abnormalities such as trisomy 18 (Wynne-Davies, 1970). Genetic Heterogeneity of Developmental Dysplasia of the Hip Developmental dysplasia of the hip-1 (DDH1) maps to chromosome 13q22; DDH2 (615612) maps to chromosome 3p21.

Emanuel syndrome is characterized by pre- and postnatal growth deficiency, microcephaly, hypotonia, severe developmental delays, ear anomalies, preauricular tags or pits, cleft or high-arched palate, congenital heart defects, kidney abnormalities, and genital abnormalities in males.

CODAS is an acronym for cerebral, ocular, dental, auricular, and skeletal anomalies. CODAS syndrome is a rare disorder characterized by a distinctive constellation of features that includes developmental delay, craniofacial anomalies, cataracts, ptosis, median nasal groove, delayed tooth eruption, hearing loss, short stature, delayed epiphyseal ossification, metaphyseal hip dysplasia, and vertebral coronal clefts (summary by Strauss et al., 2015).

Heterotaxy Heterotaxy ('heter' meaning 'other' and 'taxy' meaning 'arrangement'), or situs ambiguus, is a developmental condition characterized by randomization of the placement of visceral organs, including the heart, lungs, liver, spleen, and stomach. The organs are oriented randomly with respect to the left-right axis and with respect to one another (Srivastava, 1997). Heterotaxy is a clinically and genetically heterogeneous disorder. Multiple Types of Congenital Heart Defects Congenital heart defects (CHTD) are among the most common congenital defects, occurring with an incidence of 8/1,000 live births. The etiology of CHTD is complex, with contributions from environmental exposure, chromosomal abnormalities, and gene defects. Some patients with CHTD also have cardiac arrhythmias, which may be due to the anatomic defect itself or to surgical interventions (summary by van de Meerakker et al., 2011). Reviews Obler et al. (2008) reviewed published cases of double-outlet right ventricle and discussed etiology and associations. Genetic Heterogeneity of Visceral Heterotaxy See also HTX2 (605376), caused by mutation in the CFC1 gene (605194) on chromosome 2q21; HTX3 (606325), which maps to chromosome 6q21; HTX4 (613751), caused by mutation in the ACVR2B gene (602730) on chromosome 3p22; HTX5 (270100), caused by mutation in the NODAL gene (601265) on chromosome 10q22; HTX6 (614779), caused by mutation in the CCDC11 gene (614759) on chromosome 18q21; HTX7 (616749), caused by mutation in the MMP21 gene (608416) on chromosome 10q26; HTX8 (617205), caused by mutation in the PKD1L1 gene (609721) on chromosome 7p12; HTX9 (618948), caused by mutation in the MNS1 gene (610766) on chromosome 15q21; HTX10 (619607), caused by mutation in the CFAP52 gene (609804) on chromosome 17p13; HTX11 (619608), caused by mutation in the CFAP45 gene (605152) on chromosome 1q23; and HTX12 (619702), caused by mutation in the CIROP gene (619703) on chromosome 14q11. Genetic Heterogeneity of Multiple Types of Congenital Heart Defects An X-linked form of CHTD, CHTD1, is caused by mutation in the ZIC3 gene on chromosome Xq26. CHTD2 (614980) is caused by mutation in the TAB2 gene (605101) on chromosome 6q25. A form of nonsyndromic congenital heart defects associated with cardiac rhythm and conduction disturbances (CHTD3; 614954) has been mapped to chromosome 9q31. CHTD4 (615779) is caused by mutation in the NR2F2 gene (107773) on chromosome 15q26. CHTD5 (617912) is caused by mutation in the GATA5 gene (611496) on chromosome 20q13. CHTD6 (613854) is caused by mutation in the GDF1 gene (602880) on chromosome 19p13. CHTD7 (618780) is caused by mutation in the FLT4 gene (136352) on chromosome 5q35. CHTD8 (619657) is caused by mutation in the SMAD2 gene (601366) on chromosome 18q21. CHTD9 (620294) is caused by mutation in the PLXND1 gene (604282) on chromosome 3q22.

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.

Uruguay faciocardiomusculoskeletal syndrome (FCMSU) is an X-linked disorder in which affected males have a distinctive facial appearance, muscular hypertrophy, and cardiac ventricular hypertrophy leading to premature death. Additional features include large, broad, and deformed hands and feet, congenital hip dislocation, and scoliosis (summary by Xue et al., 2016).

Simpson-Golabi-Behmel syndrome type 2 (SGBS2) is an X-linked recessive disorder in which affected males have severely impaired intellectual development, ciliary dyskinesia, and macrocephaly (summary by Budny et al., 2006). For a general phenotypic description and a discussion of genetic heterogeneity of Simpson-Golabi-Behmel syndrome, see 312870.

Carey et al. (1978) gave the name OEIS complex to a combination of defects comprising omphalocele, exstrophy of the cloaca, imperforate anus, and spinal defects. This rare complex is thought to represent the most severe end of a spectrum of birth defects, the exstrophy-epispadias sequence, which, in order of increasing severity, includes phallic separation with epispadias, pubic diastasis, exstrophy of the bladder (600057), cloacal exstrophy, and OEIS complex. Very few instances of recurrence of anomalies in this cluster have been reported.

KAT6B disorders include genitopatellar syndrome (GPS) and Say-Barber-Biesecker-Young-Simpson variant of Ohdo syndrome (SBBYSS) which are part of a broad phenotypic spectrum with variable expressivity; individuals presenting with a phenotype intermediate between GPS and SBBYSS have been reported. Both phenotypes are characterized by some degree of global developmental delay / intellectual disability; hypotonia; genital abnormalities; and skeletal abnormalities including patellar hypoplasia/agenesis, flexion contractures of the knees and/or hips, and anomalies of the digits, spine, and/or ribs. Congenital heart defects, small bowel malrotation, feeding difficulties, slow growth, cleft palate, hearing loss, and dental anomalies have been observed in individuals with either phenotype.

Kaufman oculocerebrofacial syndrome (KOS) is characterized by developmental delay, severe intellectual disability, and distinctive craniofacial features. Most affected children have prenatal-onset microcephaly, hypotonia, and growth deficiency. Feeding issues, ocular abnormalities, hearing impairment, and respiratory tract abnormalities are common. Ocular abnormalities can include structural abnormalities (microcornea or microphthalmia, coloboma, optic nerve hypoplasia), refractive errors (myopia ± astigmatism, hyperopia), strabismus, and entropion. Both conductive and sensorineural hearing loss have been reported as well as mixed conductive-sensorineural hearing loss of variable severity. Breathing problems can lead to prolonged hospitalization after birth in more than half of individuals. Less common findings include ectodermal abnormalities, cardiac manifestations, urogenital abnormalities, seizures, and skeletal abnormalities.

This syndrome has main characteristics of bowing of the femora, aplasia or hypoplasia of the fibulae and poly, oligo and syndactyly. It has been reported in 11 patients. Most of the patients also had a hypoplastic pelvis and hypoplasia of the fingers and fingernails. Some had congenital dislocation of the hip, absence or fusion of tarsal bones, absence of various metatarsals and hypoplasia and aplasia of the toes. The syndrome is caused by a partial loss of WNT7A function (gene mapped to 3p25).

Yunis-Varon syndrome 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).

Spondyloepimetaphyseal dysplasia with joint laxity type 2 (SEMDJL2) is characterized by short stature, distinctive midface retrusion, progressive knee malalignment (genu valgum and/or varum), generalized ligamentous laxity, and mild spinal deformity. Intellectual development is not impaired. Radiographic characteristics include significantly retarded epiphyseal ossification that evolves into epiphyseal dysplasia and precocious osteoarthritis, metaphyseal irregularities and vertical striations, constricted femoral neck, slender metacarpals and metatarsals, and mild thoracolumbar kyphosis or scoliosis with normal or mild platyspondyly (summary by Min et al., 2011). For a discussion of genetic heterogeneity of SEMD with joint laxity, see SEMDJL1 (271640).

A rare focal skeletal dysostosis with characteristics of symmetrical hypoplasia of the scapulae and the iliac wings of the pelvis. Approximately 10 patients have been reported so far. Additional skeletal abnormalities may include hypoplasia of the clavicles, ribs, femora and fibula, together with spina bifida and prominent lumbar lordosis. Eye anomalies (coloboma of iris and retina) have occasionally been reported. Intelligence is described as normal. Pelvis-shoulder dysplasia seems to be a genetically heterogeneous disorder but no causative genes have been identified so far.

A rare, genetic, multiple congenital anomalies/dysmorphic syndrome characterized by the triad: congenital, bilateral, symmetrical, subtotal, external auditory canal atresia, bilateral vertical talus and increased interocular distance.

The phenotype of autosomal recessive cutis laxa type II (ARCL2) includes cutis laxa of variable severity, abnormal growth, developmental delay, and associated skeletal abnormalities (summary by Morava et al., 2009). No specific clinical features distinguish ARCL2A (219200), which includes a glycosylation defect, and ARCL2B, in which abnormal glycosylation has not been reported (Morava et al., 2009; Guernsey et al., 2009). For a phenotypic description and discussion of genetic heterogeneity of autosomal recessive cutis laxa, see ARCL1A (219100).

Ogden syndrome (OGDNS) is an X-linked neurodevelopmental disorder characterized by postnatal growth failure, severely delayed psychomotor development, variable dysmorphic features, and hypotonia. Many patients also have cardiac malformations or arrhythmias (summary by Popp et al., 2015).

Congenital absence of the nails is a rare condition. Some pedigrees display complete congenital absence of the nails (see, e.g., NDNC4, 206800), whereas in other pedigrees there is only partial congenital anonychia, with the thumbs and great toes most severely affected and progressively less severe changes in the more lateral digits (summary by Charteris, 1918). This form of nail disorder is referred to here as nonsyndromic congenital nail disorder-6 (NDNC6). For a list of other nonsyndromic congenital nail disorders and a discussion of genetic heterogeneity, see NDNC1 (161050).

Any hypothyroidism, congenital, nongoitrous in which the cause of the disease is a mutation in the THRA gene.

This autosomal recessive form of distal arthrogryposis, designated DA5D by McMillin et al. (2013), is characterized by severe camptodactyly of the hands, including adducted thumbs and wrists; mild camptodactyly of the toes; clubfoot and/or a calcaneovalgus deformity; extension contractures of the knee; unilateral ptosis or ptosis that is more severe on one side; a round-shaped face; arched eyebrows; a bulbous, upturned nose; and micrognathia. Notably, these patients do not have ophthalmoplegia. For a general phenotypic description and discussion of genetic heterogeneity of distal arthrogryposis, see DA1A (108120). For discussion of genetic heterogeneity of distal arthrogryposis type 5, see DA5 (108145).

Congenital myopathy-4A (CMYP4A) is an autosomal dominant disorder of the skeletal muscle characterized by the onset of muscle weakness in infancy or childhood. The severity and pattern of muscle weakness varies, but most affected individuals show mildly delayed motor development, hypotonia, generalized muscle weakness, and weakness of the proximal limb muscles and neck muscles, resulting in difficulty running and easy fatigability. Many patients have respiratory insufficiency with reduced vital capacity, sometimes requiring noninvasive ventilatory assistance. Other common features include myopathic facies, high-arched palate, myasthenia, scapular winging, and scoliosis. Histologic findings on skeletal muscle biopsy are variable, even in patients with the same mutation. Muscle fibers can contain nemaline rod inclusions, subsarcolemmal 'cap' structures, and fiber-type disproportion (Clarke et al., 2008; Waddell et al., 2010; Malfatti et al., 2013). For a discussion of genetic heterogeneity of congenital myopathy, see CMYP1A (117000). For a discussion of genetic heterogeneity of nemaline myopathy, see 256030.

CAGSSS, which comprises cataracts, growth hormone deficiency, sensory neuropathy, sensorineural hearing loss, and skeletal dysplasia, is an autosomal recessive multisystemic disorder with a highly variable phenotypic spectrum. Not all of these features are always present, and almost all the features may present at different times and/or become more apparent with age. The skeletal features are consistent with spondyloepimetaphyseal dysplasia (SEMD) (summary by Vona et al., 2018). One family had a distinctive presentation with infantile-onset intractable seizures and cortical abnormalities reminiscent of Leigh syndrome (see 256000). The correlation between genotype and phenotype remains unclear, but since the IARS2 gene is involved in mitochondrial function, heterogeneous manifestations can be expected (Takezawa et al., 2018).

PPP2R5D-related neurodevelopmental disorder is characterized by mild to severe neurodevelopmental delay. Pronounced hypotonia with delay in gross motor skills is common. Onset of independent walking varies widely and ataxia is reported. All reported individuals have speech impairment, with a wide range of abilities. Autism spectrum disorder is reported in six individuals. Macrocephaly is common. Seizures and ophthalmologic abnormalities are reported in fewer than half of individuals. Additional anomalies include skeletal, endocrine, and cardiac malformations, each reported in a few individuals. To date, 23 individuals with PPP2R5D-related neurodevelopmental disorder have been reported.

Frontometaphyseal dysplasia (FMD) is a progressive sclerosing skeletal dysplasia characterized by supraorbital hyperostosis, undermodeling of the small bones, and small and large joint contractures, as well as extraskeletal developmental abnormalities, primarily of the cardiorespiratory system and genitourinary tract. Patients with FMD2 appear to have a propensity for keloid formation (summary by Wade et al., 2016). For a discussion of genetic heterogeneity of frontometaphyseal dysplasia, see FMD1 (305620).

Bone marrow failure syndrome-3 is an autosomal recessive disorder characterized by onset of pancytopenia in early childhood. Patients may have additional variable nonspecific somatic abnormalities, including poor growth, microcephaly, and skin anomalies (summary by Tummala et al., 2016). BMFS3 has a distinct phenotype and may include features that overlap with Shwachman-Diamond syndrome (SDS1; 260400), such as pancreatic insufficiency and short stature, and with dyskeratosis congenita (see, e.g., DKCA1, 127550), such as dental and hair abnormalities and shortened telomeres. In addition, some patients may have joint and skeletal abnormalities, impaired development, and retinal dysplasia (summary by D'Amours et al., 2018). For a discussion of genetic heterogeneity of BMFS, see BMFS1 (614675).

Schwartz-Jampel syndrome is a rare condition characterized by permanent muscle stiffness (myotonia) and bone abnormalities known as chondrodysplasia. The signs and symptoms of this condition become apparent sometime after birth, usually in early childhood. Either muscle stiffness or chondrodysplasia can appear first. The muscle and bone abnormalities worsen in childhood, although most affected individuals have a normal lifespan. The specific features of Schwartz-Jampel syndrome vary widely.\n\nMyotonia involves continuous tensing (contraction) of muscles used for movement (skeletal muscles) throughout the body. This sustained muscle contraction causes stiffness that interferes with eating, sitting, walking, and other movements. Sustained contraction of muscles in the face leads to a fixed, "mask-like" facial expression with narrow eye openings (blepharophimosis) and pursed lips. This facial appearance is very specific to Schwartz-Jampel syndrome. Affected individuals may also be nearsighted and experience abnormal blinking or spasms of the eyelids (blepharospasm).\n\nChondrodysplasia affects the development of the skeleton, particularly the long bones in the arms and legs and the bones of the hips. These bones are shortened and unusually wide at the ends, so affected individuals have short stature. The long bones may also be abnormally curved (bowed). Other bone abnormalities associated with Schwartz-Jampel syndrome include a protruding chest (pectus carinatum), abnormal curvature of the spine, flattened bones of the spine (platyspondyly), and joint abnormalities called contractures that further restrict movement.\n\nResearchers originally described two types of Schwartz-Jampel syndrome. Type 1 has the signs and symptoms described above, while type 2 has more severe bone abnormalities and other health problems and is usually life-threatening in early infancy. Researchers have since discovered that the condition they thought was Schwartz-Jampel syndrome type 2 is actually part of another disorder, Stüve-Wiedemann syndrome, which is caused by mutations in a different gene. They have recommended that the designation Schwartz-Jampel syndrome type 2 no longer be used.

Branchiootorenal spectrum disorder (BORSD) is characterized by malformations of the outer, middle, and inner ear associated with conductive, sensorineural, or mixed hearing impairment, branchial fistulae and cysts, and renal malformations ranging from mild renal hypoplasia to bilateral renal agenesis. Some individuals progress to end-stage renal disease (ESRD) later in life. Extreme variability can be observed in the presence, severity, and type of branchial arch, otologic, audiologic, and renal abnormality from right side to left side in an affected individual and also among individuals in the same family.

SMALED2B is a severe neuromuscular disorder with onset in utero. Affected individuals show decreased fetal movements and are usually born with congenital contractures consistent with arthrogryposis multiplex congenita (AMC). After birth, they have severe hypotonia and muscle atrophy as well as respiratory insufficiency due to muscle weakness. Some patients may have dysmorphic facial features and/or abnormalities on brain imaging. Many patients die in early childhood (summary by Storbeck et al., 2017) For discussion of genetic heterogeneity of lower extremity-predominant spinal muscular atrophy, see SMALED1 (158600).

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.

De Barsy syndrome, or autosomal recessive cutis laxa type III (ARCL3), is characterized by cutis laxa, a progeria-like appearance, and ophthalmologic abnormalities (summary by Kivuva et al., 2008). For a phenotypic description and a discussion of genetic heterogeneity of autosomal recessive cutis laxa, see 219100. Genetic Heterogeneity of de Barsy Syndrome Also see ARCL3B (614438), caused by mutation in the PYCR1 gene (179035) on chromosome 17q25.

Neurodevelopmental disorder with hypotonia and brain abnormalities (NEDHYBA) is characterized by impaired development of motor skills, cognitive function, and speech acquisition beginning in infancy or early childhood. Some affected individuals may have feeding difficulties, seizures, behavioral abnormalities, and nonspecific dysmorphic facial features. Brain imaging shows variable abnormalities, including corpus callosum defects, cerebellar defects, and decreased white matter volume. There is significant phenotypic variability (summary by Duncan et al., 2021).

Intellectual disability and myopathy syndrome (IDMYS) is an autosomal recessive developmental disorder characterized by global developmental delay with mildly impaired intellectual development, hypotonia, muscle weakness and fatigue, and white matter abnormalities on brain imaging. Variable additional features may include sensorineural hearing loss, dysmorphic facies, and progressive heart disease (summary by Smeland et al., 2019).

Neurodevelopmental disorder with central hypotonia and dysmorphic facies (NEDCHF) is an autosomal dominant disorder characterized by global developmental delay, impaired intellectual development, seizures, distinctive facial features, scoliosis, delayed closure of the anterior fontanel, and nonspecific brain abnormalities (Wakeling et al., 2021).