Androgen receptor (AR) mediates androgen actions such as initiation and promotion of spermatogenesis and growth of accessory sex organs. There are two trinucleotide polymorphisms (CAG and GGN repeats) in exon1 of AR gene that are vary in length in population. The CAG and GGN repeats association with infertility is still unknown and this study is planned to assess the distribution of CAG and GGN repeat expansion and their roles in Iranian men’s possible infertility.
Materials and methods
To achieve this aim, eighty men were chosen (40 fertile men as a control and 40 azoospermic verified using spermogram test as an infertile group). The patients genomic DNA was extracted from their peripheral blood and the AR gene was amplified by polymerase chain reaction (PCR). For determining the number of repeats, sequencing method was used.
Our result demonstrated the means of CAG and GGN repeat length in infertile group were 23.4 and 23.7 respectively, that were significantly higher than these trinucleotide repeats in fertile men (AR-CAG mean =21.7, P=0.014 and AR-GGN mean =22.3, P=0.001). In addition, the maximum CAG repeat in azoospermic men was 29 repeats and in control group it was 27 repeats. Longest GGN repeat in infertile men was measured 30 vs. 25 in control group.
This finding indicates that some men with deficiency in spermatogenesis have longer trinucleotide repeats in the AR gene. According to the results, long stretches of tandem repeats of AR gene may negatively affect the function of the gene and consequently lead to male infertility in Iranian men.