Mendelian genetics of male infertility.

Infertility is defined as the inability of a couple to conceive despite trying for a year, and it affects approximately 15% of the reproductive-age population. It is considered a genetically lethal factor, as the family lineage stops at that individual with no progeny produced. A genetic defect associated with an infertile individual cannot be transmitted to the offspring, ensuring the maintenance of reproductive fitness of the species.