Nevoid basal cell carcinoma syndrome (NBCCS) is characterized by the development of multiple jaw keratocysts, frequently beginning in the second decade of life, and/or basal cell carcinomas (BCCs) usually from the third decade onward. Approximately 60% of individuals have a recognizable appearance with macrocephaly, frontal bossing, coarse facial features, and facial milia. Most individuals have skeletal anomalies (e.g., bifid ribs, wedge-shaped vertebrae). Ectopic calcification, particularly in the falx, is present in more than 90% of affected individuals by age 20 years. Cardiac and ovarian fibromas occur in approximately 2% and 20% of individuals respectively. Approximately 5% of all children with NBCCS develop medulloblastoma (primitive neuroectodermal tumor), generally the desmoplastic subtype. The risk of developing medulloblastoma is substantially higher in individuals with an SUFU pathogenic variant (33%) than in those with a PTCH1 pathogenic variant (<2%). Peak incidence is at age one to two years. Life expectancy in NBCCS is not significantly different from average.

Incontinentia pigmenti (IP) is a disorder that affects the skin, hair, teeth, nails, eyes, and central nervous system; it occurs primarily in females and on occasion in males. Characteristic skin lesions evolve through four stages: I. Blistering (birth to age ~4 months). II. Wart-like rash (for several months). III. Swirling macular hyperpigmentation (age ~6 months into adulthood). IV. Linear hypopigmentation. Alopecia, hypodontia, abnormal tooth shape, and dystrophic nails are observed. Neovascularization of the retina, present in some individuals, predisposes to retinal detachment. Neurologic findings including seizures, intellectual disability, and developmental delays are occasionally seen.

Aicardi syndrome is a neurodevelopmental disorder that affects primarily females. Initially it was characterized by a typical triad of agenesis of the corpus callosum, central chorioretinal lacunae, and infantile spasms. As more affected individuals have been ascertained, it has become clear that not all affected girls have all three features of the classic triad and that other neurologic and systemic defects are common, including other brain malformations, optic nerve abnormalities, other seizure types, intellectual disability of varying severity, and scoliosis.

Shprintzen-Goldberg syndrome (SGS) is characterized by: delayed motor and cognitive milestones and mild-to-moderate intellectual disability; craniosynostosis of the coronal, sagittal, or lambdoid sutures; distinctive craniofacial features; and musculoskeletal findings including olichostenomelia, arachnodactyly, camptodactyly, pectus excavatum or carinatum, scoliosis, joint hypermobility or contractures, pes planus, foot malposition, and C1-C2 spine malformation. Cardiovascular anomalies may include mitral valve prolapse, secundum atrial septal defect, and aortic root dilatation. Minimal subcutaneous fat, abdominal wall defects, and myopia are also characteristic findings.

Waardenburg syndrome type I (WS1) is an auditory-pigmentary disorder comprising congenital sensorineural hearing loss and pigmentary disturbances of the iris, hair, and skin along with dystopia canthorum (lateral displacement of the inner canthi). The hearing loss in WS1, observed in approximately 60% of affected individuals, is congenital, typically non-progressive, either unilateral or bilateral, and sensorineural. Most commonly, hearing loss in WS1 is bilateral and profound (>100 dB). The majority of individuals with WS1 have either a white forelock or early graying of the scalp hair before age 30 years. The classic white forelock observed in approximately 45% of individuals is the most common hair pigmentation anomaly seen in WS1. Affected individuals may have complete heterochromia iridium, partial/segmental heterochromia, or hypoplastic or brilliant blue irides. Congenital leukoderma is frequently seen on the face, trunk, or limbs.

The phenotypic spectrum of SOX2 disorder includes anophthalmia and/or microphthalmia, brain malformations, developmental delay / intellectual disability, esophageal atresia, hypogonadotropic hypogonadism (manifest as cryptorchidism and micropenis in males, gonadal dysgenesis infrequently in females, and delayed puberty in both sexes), pituitary hypoplasia, postnatal growth delay, hypotonia, seizures, and spastic or dystonic movements.

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.

Spondylocostal dysostosis (SCDO), defined radiographically as multiple segmentation defects of the vertebrae (M-SDV) in combination with abnormalities of the ribs, is characterized clinically by: a short trunk in proportion to height; short neck; non-progressive mild scoliosis in most affected individuals, and occasionally, more significant scoliosis. Respiratory function in neonates may be compromised by reduced size of the thorax. By age two years lung growth may improve sufficiently to support relatively normal growth and development; however, even then life-threatening complications can occur, especially pulmonary hypertension in children with severely restricted lung capacity from birth. Males with SCDO appear to be at increased risk for inguinal hernia.

Cornelia de Lange syndrome (CdLS) encompasses a spectrum of findings from mild to severe. Severe (classic) CdLS is characterized by distinctive facial features, growth restriction (prenatal onset; <5th centile throughout life), hypertrichosis, and upper-limb reduction defects that range from subtle phalangeal abnormalities to oligodactyly (missing digits). Craniofacial features include synophrys, highly arched and/or thick eyebrows, long eyelashes, short nasal bridge with anteverted nares, small widely spaced teeth, and microcephaly. Individuals with a milder phenotype have less severe growth, cognitive, and limb involvement, but often have facial features consistent with CdLS. Across the CdLS spectrum IQ ranges from below 30 to 102 (mean: 53). Many individuals demonstrate autistic and self-destructive tendencies. Other frequent findings include cardiac septal defects, gastrointestinal dysfunction, hearing loss, myopia, and cryptorchidism or hypoplastic genitalia.

Vertebral hypersegmentation and orofacial anomalies (VHO) is characterized by supernumerary cervical, thoracic, and/or lumbar vertebrae, in association with supernumerary ribs. Most patients also exhibit orofacial clefting and ear anomalies (Cox et al., 2019).

Mandibuloacral dysplasia progeroid syndrome (MDPS) is an autosomal recessive severe laminopathy-like disorder characterized by growth retardation, bone resorption, arterial calcification, renal glomerulosclerosis, and hypertension (Elouej et al., 2020).

KINSSHIP syndrome (KINS) is an autosomal dominant disorder characterized by a recognizable pattern of anomalies including developmental delay, impaired intellectual development, seizures, mesomelic dysplasia, dysmorphic facial features, horseshoe or hypoplastic kidney, and failure to thrive (summary by Voisin et al., 2021).