The purpose of this study was to investigate whether fertilization failure after in vitro fertilization could be explained by polymorphisms in MT-ATP6 and MT-CYB genes. We performed a prospective comparative study of 111 fresh IVF cycles in Han Chinese between July 2011 and February 2013. Human sperm mitochondrial DNA (mtDNA) variants in the MT-CYB and MT-ATP6 genes were screened by polymerase chain reaction (PCR) and direct sequencing. Forty-six couples had low fertilization rates (< or =30%) or total fertilization failure, and 65 controls with normal fertilization. One unreported point mutation (A15472G) was found in this study. There were 7 and 3 polymorphic sites in the MT-ATP6 and MT-CYB, respectively. Interestingly, the frequencies of points 8701 and 15301 homozygous variants in study group were significantly higher than those in control group. However, the frequencies of the points 8701, 9075 and 15,301 heterozygous variants in study group were significantly lower than those in control group (4.35% versus 16.92%, 15.22% versus 32.31% and 6.52% versus 33.84%, respectively, p < 0.05). In addition, the frequency in subjects harboring A8701G and G15301A variants in study group was significantly higher than that in control group (63.04% versus 33.85%, p < 0.05). This study suggests that, in part, polymorphisms in the MT-ATP6 and MT-CYB genes may contribute to the unexpected fertilization failure.
Keywords: Fertilization; MT-ATP6; MT-CYB; mitochondrial DNA; polymorphism.