Chromosome abnormalities in sperm from infertile men with normal somatic karyotypes: oligozoospermia

Recently, intracytoplasmic sperm injection (ICSI) has been extremely successful for the treatment of male infertility. However, transmission of cytogenetic defects to offspring is a great concern. There are two types of cytogenetic problems in patients seeking ICSI; one is the transmission of genetic defects from patients with constitutional chromosomal abnormalities and the second is the generation of de novo defects in infertile men. Generally about 5.1% of infertile men have chromosomal abnormalities. Among such infertile men, men with severe spermatogenesis defects, including oligozoospermia and azoospermia, are subjects for ICSI. Therefore it is very important to obtain cytogenetic information in these infertile patients. Furthermore, oligozoospermic men with a normal somatic karyotype also have increased frequencies of sperm chromosome abnormalities. Oligozoospermia is usually associated with other sperm alterations, for example oligoasthenozoospermia, oligoteratozoospemia and oligoasthenoteratozoospermia. In this review, the relationship between sperm concentration and sperm aneuploidy frequencies has been analyzed. The inverse correlation between the frequency of sperm aneuploidy and concentration has been reported in extensive studies. Especially in severe oligozoospermia, a significantly higher frequency of sex chromosome aneuploidy has been observed and this has been corroborated in recent clinical outcome data of ICSI.