Multiple neonatal deaths due to a homoplasmic mitochondrial DNA mutation

Mutations of mitochondrial DNA (mtDNA) are an important cause of genetic disease. We describe a family with an unusual homoplasmic mutation that resulted in six neonatal deaths and one surviving child with Leigh syndrome. The mother is clinically normal, but a severe biochemical and molecular genetic defect was present in both a fatally affected child and the mother. This family highlights the role of homoplasmic mt-tRNA mutations in genetic disease.