Mitochondrial Short-Chain Enoyl-CoA Hydratase 1 Deficiency
Patient Information
Characteristics
Background and History
This is a recently reported hereditary disorder that alters the function of some energy producing reactions in cells leading to severe neurological disease.
Clinical Correlations
Infants are born with poor muscle tone (hypotonia). Prominent early signs include a weak sucking reflex and sometimes long periods between breaths (apnea). Most infants do not achieve normal milestones such as speech and sitting alone. Erratic, roving eyes (nystagmus) has been noted. Brain imaging reveals degenerative changes in critical brain centers. Blood and cerebrospinal fluids contain increased levels of a compound known as lactic acid.
Only a few patients have been reported and the full clinical syndrome has not been established. Several infants have lived to the age of 4 years but another died of respiratory failure before one year of age.
Genetics
Inheritance
This is an autosomal recessive condition as the result of mutations in both copies of a specific gene. Parents with one copy seem to be clinically normal but the children born to two such parents each have a 25% risk of developing this disorder.
Pedigree
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
Diagnosis and Prognosis
Developmental problems may be evident to pediatricians and neurologists soon after birth. No treatment is known and death may occur in early childhood.
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