Y chromosome TSPY copy numbers and semen quality

Objective: To determine whether variation in testis-specific protein Y-encoded (TSPY) gene copy number affects semen quality.

Design: Nested case-control study.

Setting: University hospital.

Patient(s): From a consecutive cohort of 1,016 male partners of subfertile couples, unselected for sperm counts, we selected as cases 100 men with the lowest total number of progressively motile sperm (TMC) and as controls, 100 men with the highest total number of progressively motile sperm.

Intervention(s): Quantitative real-time polymerase chain reaction (PCR) and Southern blot to determine TSPY copy number.

Main outcome measure(s): TSPY copy number.

Result(s): The quantitative PCR method showed excellent agreement with the Southern blot analysis. Cases had a median TSPY copy number of 35 (range 20-73), whereas controls had a median TSPY copy number of 34 (range 26-76). This difference was not statistically significant.

Conclusion(s): We found no association between TSPY copy numbers and severe spermatogenic failure. The observed variation in TSPY copy number therefore appears to have no functional consequences for semen quality.