MedGen

Waardenburg syndrome type 3 is an auditory-pigmentary syndrome characterized by pigmentary abnormalities of the hair, skin, and eyes; congenital sensorineural hearing loss; presence of 'dystopia canthorum,' the lateral displacement of the ocular inner canthi; and upper limb abnormalities (reviews by Read and Newton, 1997 and Pingault et al., 2010). WS type 3 is also referred to as 'Klein-Waardenburg syndrome' (Gorlin et al., 1976). Clinical Variability of Waardenburg Syndrome Types 1-4 Waardenburg syndrome has been classified into 4 main phenotypes. Type I Waardenburg syndrome (WS1; 193500) is characterized by pigmentary abnormalities of the hair, including a white forelock and premature graying; pigmentary changes of the iris, such as heterochromia iridis and brilliant blue eyes; congenital sensorineural hearing loss; and 'dystopia canthorum.' WS type II (WS2) is distinguished from type I by the absence of dystopia canthorum. WS type III has dystopia canthorum and is distinguished by the presence of upper limb abnormalities. WS type IV (WS4; 277580), also known as Waardenburg-Shah syndrome, has the additional feature of Hirschsprung disease (reviews by Read and Newton, 1997 and Pingault et al., 2010). [from OMIM]

7q11.23 duplication syndrome is characterized by delayed motor, speech, and social skills in early childhood; neurologic abnormalities (hypotonia, adventitious movements, and abnormal gait and station); speech sound disorders including motor speech disorders (childhood apraxia of speech and/or dysarthria) and phonologic disorders; behavior problems including anxiety disorders (especially social anxiety disorder [social phobia]), selective mutism, attention-deficit/hyperactivity disorder, oppositional disorders, physical aggression, and autism spectrum disorder; and intellectual disability in some individuals. Distinctive facial features are common. Cardiovascular disease includes dilatation of the ascending aorta. Approximately 30% of individuals have one or more congenital anomalies. [from GeneReviews]

Spinocerebellar ataxia-29 (SCA29) is an autosomal dominant neurologic disorder characterized by onset in infancy of delayed motor development and mild cognitive delay. Affected individuals develop a very slowly progressive or nonprogressive gait and limb ataxia associated with cerebellar atrophy on brain imaging. Additional variable features include nystagmus, dysarthria, and tremor (summary by Huang et al., 2012). For a general discussion of autosomal dominant spinocerebellar ataxia, see SCA1 (164400). [from OMIM]

Cole-Carpenter syndrome-2 (CLCRP2) is a skeletal dysplasia associated with low bone mass or an osteogenesis imperfecta-like syndrome. It is characterized by bone fragility with craniosynostosis, ocular proptosis, hydrocephalus, and distinctive facial features such as marked frontal bossing, midface hypoplasia, and micrognathia (summary by Takeyari et al., 2018). [from OMIM]

EBF3 neurodevelopmental disorder (EBF3-NDD) is associated with developmental delay (DD) / intellectual disability (ID), speech delay, gait or truncal ataxia, hypotonia, behavioral problems, and facial dysmorphism. Variability between individuals with EBF3-NDD is significant. Although all affected children have DD noted in early infancy, intellect generally ranges from mild to severe ID, with two individuals functioning in the low normal range. Less common issues can include genitourinary abnormalities and gastrointestinal and/or musculoskeletal involvement. To date, 42 symptomatic individuals from 39 families have been reported. [from GeneReviews]

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). [from OMIM]

Combined oxidative phosphorylation deficiency-18 (COXPD18) is an autosomal recessive disorder of mitochondrial function characterized by intrauterine growth retardation, hypotonia, visual impairment, speech delay, and lactic acidosis associated with decreased mitochondrial respiratory chain activity. Affected patients may also show hematologic abnormalities, mainly macrocytic anemia (summary by Hildick-Smith et al., 2013). For a discussion of genetic heterogeneity of combined oxidative phosphorylation deficiency, see COXPD1 (609060). [from OMIM]

Lissencephaly-8 (LIS8) is an autosomal recessive neurologic disorder characterized by delayed psychomotor development, intellectual disability with poor or absent speech, early-onset refractory seizures, and hypotonia. Brain imaging shows variable features, including cortical gyral abnormalities and hypoplasia of the corpus callosum, brainstem, and cerebellum (Jerber et al., 2016). For a general description and a discussion of genetic heterogeneity lissencephaly, see LIS1 (607432). [from OMIM]

For the purposes of this chapter, NFIA-related disorder is defined as heterozygous inactivation or disruption of only NFIA without involvement of adjacent or surrounding genes. NFIA-related disorder comprises central nervous system abnormalities (most commonly abnormalities of the corpus callosum) with or without urinary tract defects, such as unilateral or bilateral vesicoureteral reflux and hydronephrosis. Additional features include macrocephaly, seizures, developmental delay and/or cognitive impairment, nonspecific dysmorphic features, ventriculomegaly, and hypotonia, which can exacerbate motor delay and feeding issues in infancy. Rarer features may include strabismus, cutis marmorata, or craniosynostosis of the metopic, lambdoid, or sagittal suture. [from GeneReviews]

Pontocerebellar hypoplasia type 2F (PCH2F) is an autosomal recessive neurodevelopmental disorder characterized by progressive microcephaly and variable neurologic signs and symptoms, including cognitive and motor delay, poor or absent speech, seizures, and spasticity (summary by Breuss et al., 2016). For a general phenotypic description and a discussion of genetic heterogeneity of pontocerebellar hypoplasia type 2, see PCH2A (277470). [from OMIM]

Autosomal recessive primary microcephaly-17 (MCPH17) is a severe neurologic disorder characterized by very small head circumference that is apparent at birth and worsens over time (up to -12 SD). Affected individuals have delayed psychomotor development, intellectual disability, spasticity, axial hypotonia, and dysmorphic features. Brain imaging shows a simplified gyral pattern; more severe cases have lissencephaly with hypoplasia of the brainstem and cerebellum (summary by Harding et al., 2016). For a phenotypic description and a discussion of genetic heterogeneity of primary microcephaly, see MCPH1 (251200). [from OMIM]

PI4KA-related disorder is a clinically variable disorder characterized primarily by neurologic dysfunction (limb spasticity, developmental delay, intellectual disability, seizures, ataxia, nystagmus), gastrointestinal manifestations (multiple intestinal atresia, inflammatory bowel disease), and combined immunodeficiency (leukopenia, variable immunoglobulin defects). Age of onset is typically antenatal or in early childhood; individuals can present with any combination of these features. Rare individuals present with later-onset hereditary spastic paraplegia. Brain MRI findings can include hypomyelinating leukodystrophy, cerebellar hypoplasia/atrophy, thin or dysplastic corpus callosum, and/or perisylvian polymicrogyria. [from GeneReviews]

A rare genetic syndromic intellectual disability characterized by global developmental delay and borderline to severe intellectual disability, autism spectrum disorder with obsessive behavior, stereotypies, hyperactivity but frequently friendly and affable personality, feeding difficulties, short stature, muscular hypotonia, microcephaly, characteristic dysmorphic features (hypertelorism, high arched eyebrows, ptosis, deep and/or broad nasal bridge, broad/prominent nasal tip, short and/or upturned philtrum, narrow mouth, and micrognathia), and skeletal anomalies (kyphosis and/or scoliosis, arthrogryposis, slender habitus and extremities). Other clinical features may include hernias, congenital heart defects, cryptorchidism and seizures. [from ORDO]

Autosomal recessive spinocerebellar ataxia-20 is a neurodevelopmental disorder characterized by severely delayed psychomotor development with poor or absent speech, wide-based or absent gait, coarse facies, and cerebellar atrophy (summary by Thomas et al., 2014). [from OMIM]

Hypopigmentation, organomegaly, and delayed myelination and development (HOD) is characterized by hypopigmented skin and hair with normally pigmented irides; organomegaly including enlargement of liver, kidney, and spleen; and delayed myelination on brain MRI accompanied by developmental delay in both gross and fine motor skills. Biopsy findings from skin and other organs are consistent with a lysosomal storage disorder (Nicoli et al., 2019). [from OMIM]

Beck-Fahrner syndrome (BEFAHRS) is a developmental disorder characterized by global developmental delay with variably impaired intellectual development. Affected individuals often have behavioral abnormalities, such as autistic features or attention deficit-hyperactivity disorder (ADHD), as well as learning disabilities. Most patients have hypotonia and dysmorphic facies. Some may have growth abnormalities, including overgrowth or poor growth, poor feeding, and rarely, seizures. Although both monoallelic and biallelic mutations have been reported, some heterozygous carriers in autosomal recessive families may have milder symptoms; thus, both groups are included in this entry (summary by Beck et al., 2020). [from OMIM]

Developmental delay with or without dysmorphic facies and autism (DEDDFA) is a complex neurodevelopmental disorder apparent from infancy or early childhood and associated with variably impaired intellectual development. Some patients may be severely affected with no speech and inability to walk, whereas others may be able to attend special schools or have normal intellectual function associated with autism spectrum disorder and mild speech delay. Genetic analysis has suggested that the phenotype can be broadly categorized into 2 main groups. Patients with TRRAP mutations affecting residues 1031-1159 have a more severe disorder, often with multisystem involvement, including renal, cardiac, and genitourinary systems, as well as structural brain abnormalities. Patients with mutations outside of that region tend to have a less severe phenotype with a higher incidence of autism and usually no systemic involvement. Patients in both groups usually have somewhat similar dysmorphic facial features, such as upslanting palpebral fissures, hypertelorism, low-set ears, and broad or depressed nasal bridge, although these features are highly variable (summary by Cogne et al., 2019). [from OMIM]

The core phenotype of Elsahy-Waters syndrome consists of brachycephaly, facial asymmetry, marked hypertelorism, proptosis, blepharochalasis, midface hypoplasia, broad nose with concave nasal ridge, and prognathism; radicular dentin dysplasia with consequent obliterated pulp chambers, apical translucent cysts, recurrent infections, and early loss of teeth; vertebral fusions, particularly at C2-C3; and moderate mental retardation. Skin wrinkling over the glabellar region seems common, and in males, hypospadias has always been present. Inter- and intrafamilial variability has been reported regarding the presence of vertebral fusions, hearing loss, and dentigerous cysts. Midface hypoplasia, facial asymmetry, progressive dental anomalies, and impaired cognitive development become more evident in adulthood (summary by Castori et al., 2010). [from OMIM]

Autosomal recessive intellectual developmental disorder-43 (MRT43) is characterized by impaired intellectual development, poor language skills, short stature, and dysmorphic features. Some patients may have significant motor delays (summary by Gangfuss et al., 2022). [from OMIM]

Any autosomal recessive non-syndromic intellectual disability in which the cause of the disease is a mutation in the NDST1 gene. [from MONDO]