Primary Microcephaly, Muscle Hypotonia, and Global Developmental Delay: A Case of an Exceptional Clinical Manifestation of Maternally Inherited Mitochondrial T8993T>G Mutation in MT-ATP6 Gene

Abstract

Objective: The m.8993T>G mutation in the gene MT-ATP6 (MIM:516060) which encodes subunit six of complex V (adenosine triphosphate synthase) of the mitochondrial respiratory chain is one of the more common disease associated mutations in mitochondrial DNA (mtDNA). The mutation is heteroplasmic, occurring together with wild-type mtDNA in affected individuals, and is associated with two different clinical phenotypes: NARP (neuropathy, ataxia, and retinitis pigmentosa) or MILS (maternally inherited Leigh syndrome), with the latter usually associated with a high mutation load.