Male Infertility – Genetic Causes
Chromosomal abnormalities can be carried by one or both of the prospective parents and passed on to the developing fetus, which could cause a miscarriage. These abnormalities are only detectable in the parents by a blood test called a karyotype.
Typically, a developing fetus inherits 46 chromosomes — a pair of 23 from each parent. There are many abnormalities which can occur, however, they can be organized into two basic groups: numerical abnormalities and structural abnormalities.
A common cause of chromosomal abnormalities is a structural issue called translocation. Translocation occurs when a portion of one chromosome is broken off and transferred to another chromosome. During reproduction, the abnormality may impact a fetus’ egg or sperm cells, resulting in extra genetic material or missing genetic material. Depending upon which genes are affected, translocation often leads to miscarriage.
While not correctable, diagnosis of a translocation in either parent allows for the next step of genetic counseling and assessment of a pregnancy’s success potential.
It is important to note that a successful prior pregnancy does not prove either parent is free of translocations that could affect a future pregnancy. If one or both parents are diagnosed with chromosomal abnormalities, they may elect for artificial insemination (if the male is diagnosed with a translocation) or egg donation (if the female is diagnosed with a translocation).
Types of chromosomal and genetic abnormalities
Chromosomal and genetic abnormalities associated with male infertility include Klinefelter’s syndrome, an occasional cause of the absence of sperm productions and other reproductive problems due to the presence of an extra X chromosome in the male. Noonan’s syndrome is a more unusual syndrome, carrying the symptoms of short stature, webbed neck, low set ears, and cardiovascular abnormalities.
Other less common genetic abnormalities may also link to male factor infertility.