Genetic Issues in Azoospermia
Azoospermia is the complete absence of sperm in the ejaculate in the neat and centrifuged sample. A significant proportion of sperm anomalies have been attributed to genetic causes. Almost about 200 genes are involved to control sperm motility alone. Genetic defects can be of three types. One is point mutations in single genes. The second is numerical defects in the entire chromosome. The third type is multifactorial or polygenic. As in any other genetic problems, mutations can always occur.
2-15% of infertile men have genetic issues. A karyotyping test in the blood can detect chromosomal anomalies. Men in this category usually have small testis, azoopsermia, raised FSH levels. Klinefelters syndrome is the most commonly occurring chromosomal anomaly.
XYY syndrome is another genetic condition associated with tall stature, leukemia, low sperm count, decreased intelligence and antisocial behavior. When segments of chromosomes are broken off and exchanged a translocation results. Translocations in 13,14,15,21 and 22 are involved usually in infertile men.
Y chromosome anomalies which I have already discussed in my previous blog have a firm association with male infertility. This is the “fertility chromosome”. Microdeletions occur in the Azoospermia Factor (AZF) region and account for 7-15%of sperm anomalies. These can be subdivided into a,b, and c deletions with AZFc being the most common. However, it is a boon to know that fertility is still achievable in these men with ICSI. A PCR test will identify these deletions.