OMIM ID:
Dystonia, Childhood Onset, With Optic Atrophy
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
Optic atrophy is often observed during the first decade of life and has been noted as early as 15 months. It may be congenital. Nystagmus has been seen in some patients.
Systemic Features
Signs of motor dysfunction are seen in the first decade of life, and as early as 15 months of age. Motor development may be mildly delayed. Features are variable and include facial dystonia, myoclonus, dyskinesia, dysarthria, dysphagia, limb spasticity, and chorea-like movements all of which may progress. Some patients lose independent ambulation but cognition is not affected.
Brain imaging reveals hyperintense T2-weighted signals in the basal ganglia.
Genetics
Inheritance
The transmission pattern in 5 reported families is consistent with autosomal recessive inheritance. Biallelic mutations in the MECR gene (1p35) have been found in 7 affected individuals.
This nuclear gene plays a role in mitochondrial fatty acid synthesis.
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.