Mitochondrial DNA mutations and polymorphisms in asthenospermic infertile men

In this study we performed a systematic sequence analysis of 6 mitochondrial genes (cytochrome oxidase I, cytochrome oxidase II, cytochrome oxidase III, adenosine triphosphate synthase6, ATP synthase8, and cytochrome b] in 66 infertile men suffering from asthenospermia (n = 34) in comparison to normospermic infertile men (n = 32) and fertile men (n = 100) from Tunisian population. A total of 72 nucleotide substitutions in blood cells mitochondrial DNA were found; 63 of them were previously identified and reported in the human mitochondrial DNA database (www.mitomap.org) and 9 were novel. We also detected in 3 asthenospermic patients a novel heteroplasmic missense mitochondrial mutation (m.9387 G>A) in COXIII gene (8.8 %) that was not found in any of normospermic infertile and fertile men. This mutation substituting the valine at position 61 to methionine in a conserved amino acid in the transmembrane functional domain of the polypeptide, induces a reduction of the hydropathy index (from +1.225 to +1.100) and a decrease of the protein 3D structures number (from 39 to 32) as shown by PolyPhen bioinformatic program.