AZF1
Encyclopedia
Azoospermia factor refers to one of several proteins or their genes, which are coded from the AZF region on the human male Y chromosome
. Deletions in this region are associated with inability to produce sperm. Subregions within the AZF region are AZFa (sometimes AZF1), AZFb and AZFc (together referred to as AZF2). AZF is the term used by the HUGO Gene Nomenclature Committee.
part of the long arm in Yq11.23. AZF1 is 792kb long and just distal to the centromere
of the Y chromosome
. AZF1 genes are involved in spermatogenesis
in the testes.
. However, such strategy comes has the adverse effects that some rearrangements represent a risk factor or a de-facto causative agent of spermatogenic disruption.
A specific partial deletion of AZFc called gr/gr deletion is significantly associated with male infertility
among Caucasians in Europe and the Western Pacific region.
(not having any measurable level of sperm in semen). Deletions in the USP9Y
gene, which is located within AZF1, are usually but not always associated with inability to form sperm.
Y chromosome
The Y chromosome is one of the two sex-determining chromosomes in most mammals, including humans. In mammals, it contains the gene SRY, which triggers testis development if present. The human Y chromosome is composed of about 60 million base pairs...
. Deletions in this region are associated with inability to produce sperm. Subregions within the AZF region are AZFa (sometimes AZF1), AZFb and AZFc (together referred to as AZF2). AZF is the term used by the HUGO Gene Nomenclature Committee.
AZF1
AZF1 (Azoospermia Factor 1) gene is likely located in the euchromaticEuchromatin
Euchromatin is a lightly packed form of chromatin that is rich in gene concentration, and is often under active transcription. Unlike heterochromatin, it is found in both cells with nuclei and cells without nuclei...
part of the long arm in Yq11.23. AZF1 is 792kb long and just distal to the centromere
Centromere
A centromere is a region of DNA typically found near the middle of a chromosome where two identical sister chromatids come closest in contact. It is involved in cell division as the point of mitotic spindle attachment...
of the Y chromosome
Y chromosome
The Y chromosome is one of the two sex-determining chromosomes in most mammals, including humans. In mammals, it contains the gene SRY, which triggers testis development if present. The human Y chromosome is composed of about 60 million base pairs...
. AZF1 genes are involved in spermatogenesis
Spermatogenesis
Spermatogenesis is the process by which male primary germ cells undergo division, and produce a number of cells termed spermatogonia, from which the primary spermatocytes are derived. Each primary spermatocyte divides into two secondary spermatocytes, and each secondary spermatocyte into two...
in the testes.
AZF2
Originally, an AZFb and AZFc genes were identified and thought to be separate regions. They were later found to be overlapping and are now referred to as AZF2.AZFc
AZFc is one of the most genetically dynamic regions in the human genome, possibly serving as counter against the genetic degeneracy associated with the lack of a partner chromosome during meiosisMeiosis
Meiosis is a special type of cell division necessary for sexual reproduction. The cells produced by meiosis are gametes or spores. The animals' gametes are called sperm and egg cells....
. However, such strategy comes has the adverse effects that some rearrangements represent a risk factor or a de-facto causative agent of spermatogenic disruption.
A specific partial deletion of AZFc called gr/gr deletion is significantly associated with male infertility
Male infertility
Male infertility refers to the inability of a male to achieve a pregnancy in a fertile female. In humans it accounts for 40-50% of infertility. Male infertility is commonly due to deficiencies in the semen, and semen quality is used as a surrogate measure of male fecundity.-Pre-testicular...
among Caucasians in Europe and the Western Pacific region.
AZF mutations
Mutations or deletions in the AZF genes are associated with inability or lessened ability to create sperm. It may cause azoospermiaAzoospermia
Azoospermia is the medical condition of a male not having any measurable level of sperm in his semen. It is associated with very low levels of fertility or even sterility, but many forms are amenable to medical treatment...
(not having any measurable level of sperm in semen). Deletions in the USP9Y
USP9Y
Ubiquitin specific peptidase 9, Y-linked , also known as USP9Y, is an enzyme which in humans is encoded by the USP9Y gene. It is required for sperm production...
gene, which is located within AZF1, are usually but not always associated with inability to form sperm.