Ataxia, and Hypoplasia of the corpus callosum

Hypomyelinating leukodystrophy-11 is an autosomal recessive neurologic disorder characterized by delayed psychomotor development and other neurologic features associated with hypomyelination on brain imaging. Some patients may have additional nonneurologic features, particularly dental abnormalities and possibly hypogonadotropic hypogonadism (summary by Thiffault et al., 2015).For a general phenotypic description and a discussion of genetic heterogeneity of HLD, see {312080}.

• Intellectual disability
• Global developmental delay
• Ataxia
• Spasticity
• Myopia

SOURCES: OMIM MENDELIAN

• Global developmental delay
• Generalized hypotonia
• Ataxia
• Nystagmus
• Strabismus

SOURCES: OMIM MENDELIAN

• Seizures
• Global developmental delay
• Generalized hypotonia
• Ataxia
• Visual impairment

SOURCES: OMIM MENDELIAN

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

SOURCES: OMIM MENDELIAN

• Intellectual disability
• Ataxia
• Nystagmus
• Spasticity
• Hyperreflexia

SOURCES: OMIM MENDELIAN

Autosomal recessive mental retardation-53 is a neurodevelopmental disorder characterized by severely delayed psychomotor development, hypotonia apparent since infancy, and early-onset seizures in most patients. Some patients may have additional features, such as cerebellar hypoplasia and ataxia. MRT53 is one of a group of similar neurologic disorders resulting from biochemical defects in the glycosylphosphatidylinositol (GPI) biosynthetic pathway (summary by Makrythanasis et al., 2016).For a discussion of genetic heterogeneity of GPI biosynthesis defects, see GPIBD1 (OMIM ).

MENTAL RETARDATION, AUTOSOMAL RECESSIVE 53; MRT53 Is also known as glycosylphosphatidylinositol biosynthesis defect 13|gpibd13

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

SOURCES: OMIM MENDELIAN

Benign familial neonatal-infantile seizures (BFNIS) is a benign familial epilepsy syndrome with an intermediate phenotype between benign familial neonatal seizures (BFNS) and benign familial infantile seizures (BFIS; see these terms). So far, this syndrome has been described in multiple members of 10 families. Age of onset in these BFNIS families varied from 2 days to 6 months, with spontaneous resolution in most cases before the age of 12 months. Like BFNS and BFIS, seizures in BFNIS generally occur in clusters over one or a few days with posterior focal seizure onset. BFNIS is caused by mutations in the SCN2A gene (2q24.3), encoding the voltage-gated sodium channel alpha-subunit Na(V)1.2. Transmission is autosomal dominant.

BENIGN FAMILIAL NEONATAL-INFANTILE SEIZURES Is also known as bfnis|benign neonatal-infantile epilepsy

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

SOURCES: ORPHANET OMIM MENDELIAN

• Generalized hypotonia
• Ataxia
• Nystagmus
• Spasticity
• Delayed speech and language development

SOURCES: OMIM MENDELIAN

Hypomyelinating leukodystrophy-16 is an autosomal dominant neurologic disorder characterized by onset of hypotonia, nystagmus, and mildly delayed motor development in infancy. Affected individuals have motor disabilities, including ataxic or broad-based gait, hyperreflexia, intention tremor, dysmetria, and a mild pyramidal syndrome. Some patients have cognitive impairment, whereas others may have normal cognition or mild intellectual disability with speech difficulties. Brain imaging typically shows hypomyelination, leukodystrophy, and thin corpus callosum (summary by Simons et al., 2017).For a general phenotypic description and a discussion of genetic heterogeneity of hypomyelinating leukodystrophy, see {312080}.

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

SOURCES: OMIM MENDELIAN

Lichtenstein-Knorr syndrome is an autosomal recessive neurologic disorder characterized by postnatal onset of severe progressive sensorineural hearing loss and progressive cerebellar ataxia. Features usually develop in childhood or young adulthood (summary by Guissart et al., 2015).

PROGRESSIVE AUTOSOMAL RECESSIVE ATAXIA-DEAFNESS SYNDROME Is also known as scar19|progressive autosomal recessive ataxia-sensorineural hearing loss syndrome|lichtenstein-knorr syndrome|spinocerebellar ataxia, autosomal recessive 19

• Seizures
• Short stature
• Hearing impairment
• Ataxia
• Nystagmus

SOURCES: OMIM ORPHANET MENDELIAN