Is the CAG repeat of mitochondrial DNA polymerase gamma (POLG) associated with male infertility? A multi-centre French study

BACKGROUND

Recent data emphasized the implication of polymerase gamma (POLG) CAG repeats in infertility, making it a very attractive gene for study. A comparison of POLG CAG repeats in infertile and fertile men showed a clear association between the absence of the usual 10-CAG allele and male infertility, excluding azoospermia. It has also been suggested that the POLG gene polymorphism should be considered as a possible contributing factor in unexplained couple infertility where semen parameters are normal. In this study, we investigated the POLG CAG repeats, in a well-defined population of patients with severe male factor infertility.

METHODS

We conducted a large study of POLG CAG repeats in 433 infertile and 91 fertile, normozoospermic and healthy males. In all subjects, phenotypic data, including semen parameters, hormonal status and clinical profiles, were available.

RESULTS

Thirteen 'homozygous mutants' (3%) were found among the 433 idiopathic infertile patients. The follow-up of the 13 'homozygous mutant' resulted in pregnancy for more than half of the couples, through assisted reproductive techniques or even spontaneously. In addition, one 'homozygous mutant' was identified in 91 fertile men (1.1%)

CONCLUSION

Under our conditions, our study does not confirm any relationship between the polymorphic CAG repeat in the POLG gene and male infertility.

A simple, low cost and non-invasive method for screening Y-chromosome microdeletions in infertile men

BACKGROUND

Recent investigations emphasized a high prevalence of Y-chromosome microdeletions in men having severely impaired spermatogenesis. Screening of these men is recommended prior to assisted reproduction techniques.

METHODS

The aim of this study was to define a reliable and efficient method to detect Y-chromosome deletions in infertile men. At first the feasibility of using a cytobrush to collect buccal cells as a source of DNA was tested. Then, a multiplex PCR in accordance with European recommendations (European Andrology Academia: EAA) was compared with a commercial kit. The test population consisted of 18 infertile male patients (with a known Y-deletion). Both buccal and blood cells were used for DNA extraction. A specific DNA extraction protocol was carried out on the buccal cells.

RESULTS

Between 4-10 micro g of DNA were retrieved per brush, allowing for several PCR attempts. The commercial kit failed to detect an AZFa deletion. Furthermore, markers sY130, sY133 and sY153, included in the kit, are not reliable. Both false negative and false positive results were generated by the commercial kit.

CONCLUSION

A multiplex PCR performed pursuant to EAA recommendations is proposed. When the testing is conducted with DNA extracted from buccal cells, this protocol is simple, accurate and affordable.