Genetic Abnormalities—Micro Y Deletion (also referred to as Y Chromosone Microdeletion or YCM) (Men)
What It Is
In about 10 to 15 percent of cases of male infertility involving no blockage and no sperm, genetic testing will reveal a missing sex chromosome. The condition is called “micro Y deletion,” for a missing piece of the Y—male—chromosome. Human beings have 46 chromosomes, males have one X chromosome and one Y chromosome and females have two X chromosomes. The Y chromosome carries the genes that are responsible for producing sperm.
Who Gets It
Many men with YCM exhibit no symptoms and lead normal lives. However, the condition is often associated with reduced fertility. Y chromosome infertility is characterized by azoospermia (no sperm), or mild to severe oligozoospermia (some sperm, but below normal levels).
How It's Diagnosed/Detected
There are usually no symptoms of YCM, although physical examination may reveal small testes and/or the absence of one or both testes from the scrotum. If other reasons for azoospermia, oligozoospermia and/or abnormal sperm morphology/motility have been eliminated in an otherwise healthy man, cytogenetic testing may reveal chromosome abnormalities.
How It Affects Fertility
Men with YCM usually can’t get a partner pregnant without medical intervention.
In a 2004 study, a man suffering from azoospermia with a Y-chromosome microdeletion was able to produce a small number of sperm after a 6-month treatment with gonadotropins (recombinant FSH). Those spermatozoa from the man’s ejaculate were successfully used to achieve pregnancy (and resulted in healthy twin girls) via IVF (in vitro fertilization).
A new technique that involves removing tiny pieces of testicular tissue containing small amounts of sperm make it possible for half of men with YCM to overcome infertility and father a child. Artificial techniques of reproduction have advanced to the point where a single sperm can be physically injected into an egg through intracytoplasmic sperm injection (ICSI). ICSI has dramatically changed the treatment available for even the most severe male factor infertility. Unfortunately helping men with micro Y deletion father children almost guarantees that their male children will have the same infertility problem. (Their daughters will not.) However, these children (boys and girls) will be healthy in every other way.
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