episodic apnea

Infantile Cerebellar-Retinal Degeneration

Clinical Characteristics
Ocular Features: 

Visual tracking can be normal during the newborn period but lack of visual fixation and attention soon become evident.  Strabismus, nystagmus, and abnormal pursuit movements are often present.  Optic atrophy has been reported as early as 3 years of age.  VEP and ERG responses are extinguished in the first two years. The nystagmus may be multidirectional.  Acuity loss seems to be progressive.  A progressive retinal degeneration (not further characterized) has been reported.

Systemic Features: 

Infants generally appear normal at birth.  Within the first 6 months they show signs of developmental delay and neurological signs such as truncal hypotonia, seizures, athetosis and head bobbing.  Milestones of sitting, rolling over, and reactions to others are seldom achieved.  Cerebellar brain imaging shows progressive atrophy in all patients and some have cortical atrophy as well.  Some patients have evidence of hearing loss.   Severe failure to thrive and psychomotor delays are usually present.  Death may occur within several months of birth although some live for several decades.

Genetics

This condition results from homozygous or compound heterozygous mutations in the ACO2 gene (22q13.2).  The mutation has also been associated with optic atrophy 9 (616289).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment beyond supportive care is known.

References
Article Title: 

Mutations in the tricarboxylic acid cycle enzyme, aconitase 2, cause either isolated or syndromic optic neuropathy with encephalopathy and cerebellar atrophy

Metodiev MD, Gerber S, Hubert L, Delahodde A, Chretien D, Gerard X, Amati-Bonneau P, Giacomotto MC, Boddaert N, Kaminska A, Desguerre I, Amiel J, Rio M, Kaplan J, Munnich A, Rotig A, Rozet JM, Besmond C. Mutations in the tricarboxylic acid cycle enzyme, aconitase 2, cause either isolated or syndromic optic neuropathy with encephalopathy and cerebellar atrophy. J Med Genet. 2014 Dec;51(12):834-8.

PubMed ID: 
25351951

Mitochondrial Short-Chain Enoyl-CoA Hydratase 1 Deficiency

Clinical Characteristics
Ocular Features: 

The ocular phenotype has not been thoroughly studied.  Nystagmus has been reported in several infants.

Systemic Features: 

Evidence of severe psychomotor retardation is evident at birth or shortly thereafter.  Neonatal hypotonia with a poor suck reflex and episodic apnea is evident.  Spasticity may become evident later.  Brain imaging shows T-weighted hyperintensity areas in the basal ganglia resembling Leigh syndrome lesions.  The corpus callosum appears thin.  Serum and CSF lactate is elevated and decreased activity of the pyruvate dehydrogenase complex is present.

Infants do not achieve normal developmental milestones such as speech or sitting unsupported and several have died early in childhood from cardiorespiratory failure, possibly related to a combined mitochondrial respiratory chain dysfunction.

Genetics

The transmission pattern in several families is consistent with autosomal recessive inheritance.  Compound heterozygous mutations have been found in the ECHS1 gene (10q26.3).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 
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