Absence of association of androgen receptor trinucleotide expansion and poor semen quality

Area of Science:

• Human genetics
• Reproductive medicine
• Molecular biology

Background:

• The androgen receptor (AR) gene's CAG trinucleotide repeat (TNR) polymorphism is implicated in male fertility.
• Previous studies suggest a link between AR CAG repeat length and semen quality, though findings vary across populations.

Purpose of the Study:

• To investigate the association between AR gene CAG TNR variation and semen quality in a Caucasian population.
• To examine the prevalence of Y-chromosome microdeletions in men with poor semen quality.
• To explore the relationship between AR CAG repeat number and Y-chromosome microdeletions.

Main Methods:

• Polymerase chain reaction (PCR) amplification and DNA sequencing of the AR TNR region.
• Screening for Y-chromosome AZFc region microdeletions.
• Comparison of CAG repeat numbers and microdeletion status between men with normal and poor semen quality.

Main Results:

• No significant difference in AR CAG repeat number was observed between men with poor semen quality (mean 21.46) and normal semen quality (mean 20.99).
• Y-chromosome microdeletions were detected exclusively in men with suboptimal semen parameters (7.4%).
• The presence of Y-chromosome microdeletions was not correlated with AR CAG repeat number.

Conclusions:

• The study refutes the hypothesis that higher AR CAG repeat numbers are associated with male infertility in this Caucasian cohort.
• Findings suggest significant population-specific variations in AR CAG repeat lengths, independent of Y-chromosome microdeletions.
• AR gene CAG TNR length may not be a primary determinant of semen quality in all populations.