Familial mitochondrial DNA depletion in liver: haplotype analysis of candidate genes

Two sons and one daughter of healthy consanguineous parents presented with fatal hepatic failure in association with severe depletion of mitochondrial (mt)DNA in liver; a third son is healthy. Other published cases of mtDNA depletion concern single members of a family, which excludes the use of haplotype analysis. In the family presented here, the inheritance of the genes for mitochondrial transcription factor A (mtTFA), nuclear respiratory factor 1 (NRF-1), mitochondrial single-stranded DNA-binding protein (mtSSBP), and endonuclease G (EndoG) was studied using microsatellite markers linked to these genes. The inheritance of the gene for mtDNA polymerase (pol gamma) was studied using a polymorphic CAG repeat present within the coding region of the gene. EndoG and mtSSBP were excluded, but mtTFA remains a candidate. Pol gamma or NRF-1 involvement would be compatible only with autosomal dominant inheritance. Coding sequence analysis of NRF-1 and mtTFA revealed no novel mutations in affected individuals.