Clinically Significant Novel Mutation in the Mitochondrial DNA Detected in Patients With POF by Screening the Hyper Variable Regions 1 and 2 (HV1, 2) of Human mtDNA

Abstract

Premature ovarian failure (POF) is not a rare entity, seen in approximately 1-2% of the female population. The purpose of this present report was to investigate areas of mtDNA assumed to be regard to POF patients and to study the relationship between SNP in HV1/HV2 and POF. Therefore, development of efficient SNP assay protocols for HV1/HV2 would find susceptibility to POF as well as to pathogenesis of POF. Prospective pilot study Genomic DNA were collected from 99 POF patients (mean age 30.5±4) who were under the inclusion criteria of POF and from 80 controls (29.4±4.8). After amplification of HV1 and HV2, purified PCR products was sequenced and compared with those recorded in the mitochondrial databank (http://www.mitomap.org). Statistical analysis between the patients and the control group was assessed by Chi-square test and Fisher’s exact test (p < 0.05). All samples contained apparent mutations differing in the sequence shown in the mitochondrial databank. Most of the mutations in both POF and control sequences were single base substitutions and most of these were transitions. In both regions, transitions were 83.2%, and transversions were 5.2%, whereas the insertions and deletions were rather rare. Tabled 1 We have found a novel mutation in HV2 of noncoding regions in POF patients (table). The insertion, G251GG, in the mTF1 binding site 1 has not been described previously. A high incidence of POF among the mothers’ relatives is in accordance with the hypothesis that mtDNA mutations are involved. Meanwhile, significantly lower mtDNA copy number in POF patients than in age-matched control group has been reported (2004 ASRM Lee et al.). However, mtDNA testing targets only a small fraction of the variation, and is usually restricted to ∼610bp encompassing HV1 and HV 2 of the control region. Likewise, specific to the detection of SNPs, many potential options are currently available for informative SNPs within HV1 and HV2 which are known as having high mutation rate. As shown in tables, the majority of mutations in HV1 and HV2 were transitions and a lower number of transversions was obtained. In terms of mTF1 binding site, mitochondrial transcription factor is an important regulator of both transcription and replication of mtDNA. Moreover, mitochondrial transcription factor regulates mtDNA copy number. In noncoding areas, 12.12% of the POF patients and 1.41% of the control group had above insertion. We also have found a new mutation, G205A in the H-strand which may be relevant to POF. The statistically significant mutation detected in this study is known from previous studies: T16325C in HV1. We have also been given by its high mutation rate. It may serve as a sensitive diagnostic marker with its mutation level being indicative of POF. Furthermore, mtDNA mutations may play a role in patients with POF that was unexplained.