Hearing impairment, and Delayed myelination

For a general phenotypic description and a discussion of genetic heterogeneity of Charcot-Marie-Tooth disease type 1, see CMT1B (OMIM ).CMT1A is the most common form of CMT. The average age of onset of clinical symptoms is 12.2 +/- 7.3 years. Slow nerve conduction velocity (NCV) less than 38 m/s is highly diagnostic and is a 100% penetrant phenotype independent of age ({36,39:Lupski et al., 1991, 1992}).

CHARCOT-MARIE-TOOTH DISEASE, DEMYELINATING, TYPE 1A; CMT1A Is also known as hereditary motor and sensory neuropathy ia|hmsn ia|charcot-marie-tooth neuropathy, type 1a|hmsn1a|charcot-marie-tooth disease, autosomal dominant, with focally folded myelin sheaths, type 1a

• Global developmental delay
• Hearing impairment
• Muscle weakness
• Motor delay
• Peripheral neuropathy

SOURCES: OMIM MENDELIAN

Aminoacylase 1 deficiency (ACY1D) is an inborn error of metabolism marked by a characteristic pattern of urinary N-acetyl amino acid excretion and neurologic symptoms.

NEUROLOGICAL CONDITIONS ASSOCIATED WITH AMINOACYLASE 1 DEFICIENCY Is also known as n-acyl-l-amino acid amidohydrolase deficiency|acy1d

• Intellectual disability
• Seizures
• Global developmental delay
• Generalized hypotonia
• Hearing impairment

SOURCES: OMIM ORPHANET MESH MENDELIAN

Neonatal intractable myoclonus is a severe neurologic disorder characterized by the onset of intractable myoclonic seizures soon after birth. Affected infants have intermittent apnea, abnormal eye movements, pallor of the optic nerve, and lack of developmental progress. Brain imaging shows a progressive leukoencephalopathy. Some patients may die in infancy. There is phenotypic and biochemical evidence of mitochondrial dysfunction (summary by Duis et al., 2016).

• Seizures
• Generalized hypotonia
• Hearing impairment
• Microcephaly
• Nystagmus

SOURCES: OMIM MENDELIAN

D-glyceric aciduria is a metabolic disorder characterized by D-glyceric acid excretion. It has been described in several patients. Clinical findings include progressive neurological impairment, hypotonia, seizures, failure to thrive and metabolic acidosis. Some patients had hyperglycinemia secondary to the organic acidemia. However, some of the reported patients were asymptomatic. D-glyceric aciduria is caused by D-glycerate kinase deficiency. The GLYCTK gene has been mapped to 3p21.

D-GLYCERIC ACIDURIA Is also known as d-glyceric acidemia|d-glycerate kinase deficiency|glycerate kinase deficiency

• Intellectual disability
• Seizures
• Global developmental delay
• Generalized hypotonia
• Hearing impairment

SOURCES: MESH OMIM ORPHANET MENDELIAN

NEDMIAL is a neurodevelopmental disorder characterized by severely delayed psychomotor development and hypotonia apparent from early infancy, resulting in feeding difficulties, ataxic gait or inability to walk, minimal or absent speech development, and severe intellectual disability, often with behavioral abnormalities, such as hand-flapping. Additional common features may include sleep disorder, nonspecific dysmorphic facial features, and joint hyperlaxity (summary by Lessel et al., 2017).

• Intellectual disability
• Seizures
• Global developmental delay
• Generalized hypotonia
• Hearing impairment

SOURCES: OMIM MENDELIAN

Hypomyelinating leukodystrophy-12 is an autosomal recessive neurologic disorder characterized by severely delayed or even lack of psychomotor development that becomes apparent in the first months of life. Patients are markedly disabled, with acquired microcephaly, lack of speech, and often lack of spontaneous movement due to hypotonia and spasticity. Brain imaging shows delayed myelination (summary by Edvardson et al., 2015).For a general phenotypic description and a discussion of genetic heterogeneity of HLD, see {312080}.

VPS11-RELATED AUTOSOMAL RECESSIVE HYPOMYELINATING LEUKODYSTROPHY Is also known as vps11-related autosomal recessive hypomyelinating leukoencephalopathy

• Intellectual disability
• Seizures
• Global developmental delay
• Generalized hypotonia
• Hearing impairment

SOURCES: ORPHANET OMIM MENDELIAN

SHRF is an autosomal recessive disorder characterized by short stature, brachydactyly, dysmorphic facial features, hearing loss, and visual impairment. Onset of the hearing and visual abnormalities, including retinitis pigmentosa, varies from birth to the second decade. Patients have mild intellectual disability and mild cerebellar atrophy with myelination defects on brain imaging (summary by Di Donato et al., 2016).

RETINITIS PIGMENTOSA-HEARING LOSS-PREMATURE AGING-SHORT STATURE-FACIAL DYSMORPHISM SYNDROME Is also known as retinitis pigmentosa-deafness-premature aging-short stature-facial dysmorphism syndrome

• Intellectual disability
• Global developmental delay
• Short stature
• Hearing impairment
• Nystagmus

SOURCES: ORPHANET OMIM MENDELIAN

• Intellectual disability
• Seizures
• Global developmental delay
• Generalized hypotonia
• Hearing impairment

SOURCES: OMIM MENDELIAN

Spastic paraplegia-severe developmental delay-epilepsy syndrome is a rare, genetic, complex spastic paraplegia disorder characterized by an infantile-onset of psychomotor developmental delay with severe intellectual disability and poor speech acquisition, associated with seizures (mostly myoclonic), muscular hypotonia which may be noted at birth, and slowly progressive spasticity in the lower limbs leading to severe gait disturbances. Ocular abnormalities and incontinence are commonly associated. Other symptoms may include verbal dyspraxia, hypogenitalism, macrocephaly and sensorineural hearing loss, as well as dystonic movements and ataxia with upper limb involvement.

SPASTIC PARAPLEGIA-SEVERE DEVELOPMENTAL DELAY-EPILEPSY SYNDROME Is also known as spastic paraplegia-psychomotor retardation-seizures syndrome|spprs syndrome

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

SOURCES: OMIM ORPHANET MENDELIAN

Lethal polymalformative syndrome, Boissel type is a rare, genetic, lethal, multiple congenital anomalies/dysmorphic syndrome characterized by failure to thrive, severe developmental delay, severe postanatal microcephaly, frequent congenital cardiac defects and characteristic facial dysmorphysm (including coarse face with anteverted nostrils, thin vermillion, prominent alveolar ridge and retro- or micrognatia). Additional common features include neurologic abnormalities (hyper-/hypotonia, sensorineural deafness, hydrocephalus, cerebral atrophy, seizures), as well as brachydactyly, cutis marmorata and genital anomalies.

• Seizures
• Global developmental delay
• Hearing impairment
• Microcephaly
• Growth delay

SOURCES: MESH ORPHANET OMIM MENDELIAN