Introduction: Recessive mutations in mitochondrial replication machinery primarily affects two genes, viz., c10orf2 and POLG1 (former encoding for helicase and the latter for polymerase), causing mitochondrial depletion syndrome. Mutations in c10orf2 are associated with infantile onset spinocerebellar ataxia.¹

Case description: Two siblings, one female and one male, born to a nonconsanguinous couple, presented with primarily motor developmental delay from the second half of infancy (till 6-7 months they had normal development). Walking with support was the best attained gross motor milestone, noted at the age of 8 to 10 years in both. By early second decade they became wheelchair bound. Salient features on examination were bilateral claw hands with clubfeet, scoliosis, impaired hearing, distal weakness, choreoathetosis, extensor plantars and pancerebellar involvement with relatively preserved cognition and vision (including saccades) without any obvious dysmorphism or telengiectasia. Currently the female sibling is 18 years and the male is 12 years of age.

MRI Brain had shown pancerebellar atrophy in the female sib (normal in male) and electrophysiology revealed sensory motor axonal polyneuropathy in both. Mutations for Frederich ataxia and spinocerebellar ataxias (1,2,3,6,7,8,12) were negative. The female sib also had hypergonadotrophic hypogonadism.

Both the sibs are positive for single homozygous nonsynonymous variation (p.237A) in c10orf2 gene and the parents are carriers.

Discussion: This entity is described predominantly in Finnish population. This is the first report of a caucasian family of Indian origin with a novel mutation in this gene.¹