 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) and severe oligozoospermia (less than 5 million spermatozoa in the ejaculate) males.AZF is the term used by the HUGO Gene Nomenclature Committee.