Y chromosome microdeletion

Y chromosome microdeletion is a family of genetic disorders caused by missing genes on the Y chromosome. Many men with it show no symptoms and live normal lives, but it is found in a significant number of men with reduced fertility, where sperm production ranges from low counts to a complete absence of sperm. The Y chromosome passes directly from father to son and cannot be corrected by recombining genetic information from both parents, which may leave natural selection as its main repair mechanism. The condition is diagnosed by extracting DNA from blood leukocytes and testing it against known sequence-tagged site markers by polymerase chain reaction and gel electrophoresis, a method that checks only a small part of the chromosome. Some form of microdeletion has been detected in up to 20 percent of men with reduced sperm count. Research has centred on the azoospermia factor region at Yq11, including the gr/gr deletion of AZFc, which is associated with male infertility.