In recent years the field of genetics has been able to explain human diseases to an ever increasing level; however, so far, relevant knowledge explains only a small percentage of male subfertility. The most basic test is the karyotype, which is similar to an ordinary blood test and concerns the study of human chromosomes. Humans have 46 chromosomes, two of which have to do with sex (male XY, female XX). Karyotype testing is performed on a blood sample at any point and, consequently, the genetics lab identifies the 46 chromosomes and studies whether they are normal, if any are missing, if there is a supernumerary one or if part of one has broken off and attached elsewhere (this is called migration).
Y chromosome microdeletions check
At present, newer genetic tests have been added, depending on the indications, such as the study of whether there are genetic microdeletions on the Y chromosome (which, when identified, explain some forms of male subfertility).
Cystic fibrosis check
The check for cystic fibrosis is a genetic test that concerns whether the man is a carrier of some mutation responsible for cystic fibrosis. When this is identified (approximately 4% of men and women are cystic fibrosis carriers), it may have damaged the seminal ducts (the little tubes that carry sperm).