Azoospermia factor (AZF) is one of several proteins or their genes, which are coded from the AZF region on the human male Y chromosome.[1] Deletions in this region are associated with inability to produce sperm.[2] Subregions within the AZF region are AZFa (sometimes AZF1), AZFb and AZFc (together referred to as AZF2). AZF microdeletions are one of the major causes of male infertility for azoospermia (complete absence of sperm in the ejaculate[3][4]) and severe oligozoospermia (less than 5 million spermatozoa in the ejaculate[4]) males.[5][6]AZF is the term used by the HUGO Gene Nomenclature Committee.
Of the 15% of couples who are affected by infertility, 50% of those cases are due to the male partner.[3] 15-30% of male factor infertility cases can be correlated with genetic abnormalities.[5] One of the most commonly identified genetic abnormalities in male factor infertility are microdeletions on the long arm of the Y chromosome (Yq), specifically at a region known as the azoospermic factor (AZF) region.[3]
In certain circumstances, men with AZF mutations can turn to assisted reproductive technologies (ART), such as intracytoplasmic sperm injection (ICSI), to help them overcome their suboptimal sperm quality. However, it may be more important for clinicians to screen for Yq microdeletions, due to a growing body of evidence that AZF microdeletions have the capability to be vertically transmitted to male offspring.[3][4][6] Minor et al. demonstrated that an AZFc mutation was vertically transmitted over three generations via fathers receiving reproductive assistance through ICSI.[7]