Genetics

• Y Chromosome Microdeletion (YCM) is a family of genetic disorders caused by missing gene(s) on the Y chromosome. Many men with YCM exhibit no symptoms. On the other hand, YCM is also known to be present in a significant number of men with reduced fertility.
• Men with reduced sperm production could be experiencing oligospermia, significant lack of sperm, or azoospermia, complete lack of sperm. In up to 20% of men with reduced sperm count, some form of YCM has been detected.
• The human Y chromosome is passed directly from father to son, and is not protected against accumulating copying errors, whereas other chromosomes are error corrected by recombining genetic information from mother and father. This may leave natural selection as the primary repair mechanism for the Y chromosome.
• Y chromosome microdeletion is currently diagnosed by extracting DNA from leukocytes in a man’s blood sample and performing PCR to determine the presence/absence of specific genes located on the Y chromosome.

Symptoms/Characteristics

• • Azoospermia (absence of sperm)
  • Severe oligospermia (<1 x 106 sperm/mL semen)
  • Moderate oligospermia (1-5 x 106 sperm/mL semen)
  • Mild oligospermia (5-20 x 106 sperm/mL semen)
  • Some men may have small testes and/or cryptorchidism