Intellectual disability, and Polyneuropathy

Autosomal recessive congenital cerebellar ataxia due to MGLUR1 deficiency is a rare, genetic, slowly progressive neurodegenerative disease resulting from MGLUR1 deficiency characterized by global developmental delay (beginning in infancy), mild to severe intellectual deficit with poor or absent speech, moderate to severe stance and gait ataxia, pyramidal signs (e.g. hyperreflexia) and mild dysdiadochokinesia, dysmetria, tremors, and/or dysarthria. Oculomotor signs, such as nystagmus, strabismus, ptosis and hypometric saccades, may also be associated. Brain imaging reveals progressive, generalized, moderate to severe cerebellar atrophy, inferior vermian hypoplasia, and/or constitutionally small brain.

AUTOSOMAL RECESSIVE CONGENITAL CEREBELLAR ATAXIA DUE TO MGLUR1 DEFICIENCY Is also known as autosomal recessive spinocerebellar ataxia type 13|scar13|autosomal recessive congenital cerebellar ataxia due to metabotropic glutamate receptor 1 deficiency

• Intellectual disability
• Seizures
• Global developmental delay
• Short stature
• Generalized hypotonia

SOURCES: ORPHANET OMIM MENDELIAN

• Intellectual disability
• Short stature
• Hearing impairment
• Ataxia
• Growth delay

SOURCES: ORPHANET OMIM MENDELIAN

Microcephaly, seizures, and developmental delay is an autosomal recessive neurodevelopmental disorder with onset in infancy. There is a range of phenotypic severity: some patients have a disease course consistent with early infantile epileptic encephalopathy (EIEE), whereas others have more well-controlled seizures and a protracted course associated with cerebellar atrophy and peripheral neuropathy (Shen et al., 2010 and Poulton et al., 2013).For a general phenotypic description and a discussion of genetic heterogeneity of EIEE, see EIEE1 (308350).

MICROCEPHALY, SEIZURES, AND DEVELOPMENTAL DELAY; MCSZ Is also known as epileptic encephalopathy, early infantile, 10|eiee10

• Intellectual disability
• Seizures
• Global developmental delay
• Short stature
• Generalized hypotonia

SOURCES: OMIM MENDELIAN

Complex cortical dysplasia with other brain malformations (CDCBM) is a disorder of aberrant neuronal migration and disturbed axonal guidance. Affected individuals have mild to severe mental retardation, strabismus, axial hypotonia, and spasticity. Brain imaging shows variable malformations of cortical development, including polymicrogyria, gyral disorganization, and fusion of the basal ganglia, as well as thin corpus callosum, hypoplastic brainstem, and dysplastic cerebellar vermis. Extraocular muscles are not involved (summary by Poirier et al., 2010).Mutation in the TUBB3 gene can also cause congenital fibrosis of extraocular muscles-3A (CFEOM3A ), a milder and somewhat different neurologic phenotype. Genetic Heterogeneity of Complex Cortical Dysplasia With Other Brain MalformationsSee also CDCBM2 (OMIM ), caused by mutation in the KIF5C gene (OMIM ) on chromosome 2q23; CDCBM3 (OMIM ), caused by mutation in the KIF2A gene (OMIM ) on chromosome 5q12; CDCBM4 (OMIM ), caused by mutation in the TUBG1 gene (OMIM ) on chromosome 17q21; CDCBM5 (OMIM ), caused by mutation in the TUBB2A gene (OMIM ) on chromosome 6p25; CDCBM6 (OMIM ), caused by mutation in the TUBB gene (OMIM ) on chromosome 6p21; CDCBM7 (OMIM ), caused by mutation in the TUBB2B gene (OMIM ) on chromosome 6p25; and CDCBM8 (OMIM ), caused by mutation in the TUBA8 gene (OMIM ) on chromosome 22q11.See also lissencephaly (e.g., LIS1, {607432}), which shows overlapping features and may result from mutation in tubulin genes.

• Intellectual disability
• Seizures
• Global developmental delay
• Generalized hypotonia
• Microcephaly

SOURCES: OMIM ORPHANET MENDELIAN

Hypomyelination-congenital cataract is characterized by the onset of cataract either at birth or in the first two months of life, delayed psychomotor development by the end of the first year of life and moderate intellectual deficit.

HYPOMYELINATION-CONGENITAL CATARACT SYNDROME Is also known as hypomyelination and congenital cataract: hcc

• Intellectual disability
• Seizures
• Global developmental delay
• Generalized hypotonia
• Scoliosis

SOURCES: OMIM MESH ORPHANET MENDELIAN

PBD14B is an autosomal recessive peroxisome biogenesis disorder characterized clinically by mild intellectual disability, congenital cataracts, progressive hearing loss, and polyneuropathy (Ebberink et al., 2012), all of which had been observed in patients with mild peroxisomal biogenesis disorders (e.g., Kelley et al., 1986; Poll-The et al., 1987). Additionally, recurrent migraine-like episodes following mental stress or physical exertion, not a common feature in peroxisome disorders, was reported.Thoms and Gartner (2012) classified the disorder described by Ebberink et al. (2012) in their patient as a mild 'Zellweger syndrome (OMIM ) spectrum' (ZSS) disorder. See PBD1B (OMIM ) for a phenotypic description and discussion of genetic heterogeneity of less severe phenotypes on the Zellweger syndrome spectrum. See PBD9B (OMIM ) for another atypical peroxisome biogenesis disorder.

• Intellectual disability
• Hearing impairment
• Nystagmus
• Sensorineural hearing impairment
• Muscle weakness

SOURCES: OMIM MENDELIAN

Charcot-Marie-Tooth disease type 4B3 (CMT4B3) is a subtype of Charcot-Marie-Tooth type 4 characterized by a childhood onset of slowly progressing, demyelinating sensorimotor neuropathy, focally folded myelin sheaths in nerve biopsy, reduced nerve conduction velocities (less than 38 m/s), and the typical CMT phenotype (i.e. distal muscle weakness and atrophy, and sensory loss).

CHARCOT-MARIE-TOOTH DISEASE TYPE 4B3 Is also known as charcot-marie-tooth disease with focally folded myelin|cmt4b3

• Intellectual disability
• Microcephaly
• Scoliosis
• Ataxia
• Strabismus

SOURCES: OMIM ORPHANET MENDELIAN

Waardenburg syndrome type 4 (WS4), also known as Waardenburg-Shah syndrome, is an auditory-pigmentary syndrome characterized by pigmentary abnormalities of the hair, skin, and eyes, congenital sensorineural hearing loss, and Hirschsprung disease (reviews by Read and Newton, 1997 and Pingault et al., 2010). WS type 4A is caused by mutation in the EDNRB gene (OMIM ). Clinical Variability of Waardenburg Syndrome Types 1-4Waardenburg syndrome has been classified into 4 main phenotypes. Type I Waardenburg syndrome (WS1 ) 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 (WS3 ) has dystopia canthorum and is distinguished by the presence of upper limb abnormalities. WS type 4 has the additional feature of Hirschsprung disease (reviews by Read and Newton, 1997 and Pingault et al., 2010). Genetic Heterogeneity of Waardenburg Syndrome Type 4Waardenburg syndrome type 4 is genetically heterogeneous. WS4B (OMIM ) is caused by mutation in the EDN3 gene (OMIM ) on chromosome 20q13, and WS4C (OMIM ) is caused by mutation in the SOX10 gene (OMIM ) on chromosome 22q13.

WAARDENBURG SYNDROME, TYPE 4A; WS4A Is also known as waardenburg-shah syndrome|waardenburg syndrome, type iva|ws4|waardenburg syndrome with hirschsprung disease, type 4a|shah-waardenburg syndrome

• Intellectual disability
• Global developmental delay
• Hearing impairment
• Ataxia
• Nystagmus

SOURCES: OMIM MENDELIAN

Familial acute necrotizing encephalopathy or ADANE is a potentially fatal neurological disease characterised by neuropathological lesions principally involving the brainstem, thalamus and putamen.

FAMILIAL ACUTE NECROTIZING ENCEPHALOPATHY Is also known as adane|recurrent acute necrotizing encephalopathy|ane|encephalopathy, acute necrotizing, susceptibility to

• Intellectual disability
• Seizures
• Generalized hypotonia
• Ataxia
• Spasticity

SOURCES: OMIM ORPHANET MENDELIAN

Mitochondrial DNA depletion syndrome-8A is a severe autosomal recessive disorder characterized by neonatal hypotonia, lactic acidosis, and neurologic deterioration. Renal tubular involvement may also occur (Bourdon et al., 2007).Mitochondrial DNA depletion syndrome-8B is characterized by ophthalmoplegia, ptosis, gastrointestinal dysmotility, cachexia, peripheral neuropathy, and brain MRI changes, known as the MNGIE phenotype (Shaibani et al., 2009).For a discussion of genetic heterogeneity of mtDNA depletion syndromes, see MTDPS1 (OMIM ).

MITOCHONDRIAL DNA DEPLETION SYNDROME, ENCEPHALOMYOPATHIC FORM WITH RENAL TUBULOPATHY Is also known as mitochondrial dna depletion syndrome, encephalomyopathic, with renal tubulopathy, autosomal recessive|mtdna depletion syndrome, encephalomyopathic form with renal tubulopathy

• Intellectual disability
• Seizures
• Generalized hypotonia
• Hearing impairment
• Failure to thrive

SOURCES: ORPHANET OMIM MENDELIAN