Clinical Characteristics
Ocular Features
This is an early onset (4 to 6 years of age) optic atrophy in which acuity even at that age may be only 20/200. Peripheral field constriction occurs late in contrast to its preservation in another autosomal recessive form of early onset optic atrophy, OPA6 (258500). Atrophy of the optic nerve and loss of vision also occurs more slowly in the latter.
Systemic Features
Several individuals have had systemic disease consisting of hypertrophic cardiomyopathy, MRI changes in the brain, and mild hearing loss but these may have been coincidental.
Genetics
Inheritance
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.