Defining regions of the Y-chromosome responsible for male infertility and identification of a fourth AZF region (AZFd) by Y-chromosome microdeletion detection.

Cytogenetic and molecular deletion analyses of azoospermic and oligozoospermic males have suggested the existence of AZoospermia Factor(s) (AZF) residing in deletion intervals 5 and 6 of the human Y-chromosome and coinciding with three functional regions associated with spermatogenic failure. Nonpolymorphic microdeletions in AZF are associated with a broad spectrum of testicular phenotypes. Unfortunately, Sequence Tagged Sites (STSs) employed in screening protocols range broadly in number and mapsite and may be polymorphic.

Genetic contribution to male infertility.

Worldwide, of couples trying for a child, 2-7% fail to conceive. Extensive screening programmes of men attending infertility clinics show that chromosomal and gene disorders make a significant contribution to spermatogenic impairment. It appears that an orderly genome is essential for normal germ cell development, since numerical and structural chromosome abnormalities are found in association with germ cell breakdown.

Chromosome anomalies and Y chromosome microdeletions as causal factors in male infertility.

Among the 10% or so of men who are diagnosed as oligo- or azoospermic in the absence of any physical obstruction, research is now showing that between 8 and 15% carry a microdeletion in the long arm of the Y chromosome which, by loss of specific DNA segments, leads to loss of vital genes for sperm production. Chromosomal anomalies account for approximately 2% of all men who attend infertility clinics, rising to 15% among those with azoospermia. There are serious implications for couples seeking help by intracytoplasmic sperm injection (ICSI), since chromosomal or gene defects which might normally be lost or eliminated by natural means could be transmitted in offspring.

Dynamic changes in the subnuclear organisation of pre-mRNA splicing proteins and RBM during human germ cell development.

RBM is a germ-cell-specific RNA-binding protein encoded by the Y chromosome in all mammals, implying an important and evolutionarily conserved (but as yet unidentified) function during male germ cell development. In order to address this function, we have developed new antibody reagents to immunolocalise RBM in the different cell types in the human testis. We find that RBM has a different expression profile from its closest homologue hnRNPG.

Expression of RBM in the nuclei of human germ cells is dependent on a critical region of the Y chromosome long arm.

The association of abnormal spermatogenesis in men with Y chromosome deletions suggests that genes important for spermatogenesis have been removed from these individuals. Recently, genes encoding two putative RNA-binding proteins (RBM and DAZ/SPGY) have been mapped to two different regions of the human Y chromosome. Both of these genes encode proteins that contain a single RNA recognition motif and a (different) internally repeating sequence.