Y-chromosomal genes affecting male fertility: A review

Abstract

The mammalian sex-chromosomes (X and Y) have evolved from autosomes and are involved in sex determination and reproductive traits. The Y-chromosome is the smallest chromosome that consists of 2-3% of the haploid genome and may contain between 70 and 200 genes. The Y-chromosome plays major role in male fertility and is suitable to study the evolutionary relics, speciation, and male infertility and/or subfertility due to its unique features such as long non-recombining region, abundance of repetitive sequences, and holandric inheritance pattern. During evolution, many holandric genes were deleted. The current review discusses the mammalian holandric genes and their functions. The commonly encountered infertility and/or subfertility problems due to point or gross mutation (deletion) of the Y-chromosomal genes have also been discussed. For example, loss or microdeletion of sex-determining region, Y-linked gene results in XY males that exhibit female characteristics, deletion of RNA binding motif, Y-encoded in azoospermic factor b region results in the arrest of spermatogenesis at meiosis. The holandric genes have been covered for associating the mutations with male factor infertility.

The Role of Number of Copies, Structure, Behavior and Copy Number Variations (CNV) of the Y Chromosome in Male Infertility

“…The human Y chromosome hosts two pseudoautosomal regions (PARs), named PAR1 and PAR2, which consist of 5% of the entire chromosome [90], and an MSY region (also known as non-recombining region on Y, NRY) that does not recombine with the X chromosome [91] (Figure 1). PAR1 and PAR2 recombine during meiosis with their homologous regions on the X chromosome, although with different dynamics, compared with the rest of the genome [92].…”

The avian W chromosome is a refugium for endogenous retroviruses with likely effects on female-biased mutational load and genetic incompatibilities

“…Because of their low gene content and high repeat density, SLCs were thought to not have any effect beyond sex determination and gonadal development, remaining largely understudied or even absent in the majority of the genome assemblies and studies [8]. However, recent studies on SLCs, especially in humans and other model organisms, have shown that they play roles in human diseases [9,10], male infertility [11], determining sex-specific traits [12], shaping the genome-wide heterochromatic landscape [13], exerting epistatic effects [14][15][16], reproductive isolation [17], and suppressing meiotic drivers on other chromosomes (e.g., through RNAi pathways) [18].…”

Disorder of sex development in a cat with chromosome mosaicism 37,X/38,X,r(Y)

“…However, other abnormalities, such as X monosomy (Szczerbal, Nizanski, et al., ), 37,X/38,XY mosaicism (Balogh et al., ) or X/Y translocation (Szczerbal, Stachowiak, Dzimira, Sliwa, & Switonski, ), have also been reported recently. It is known from human studies that structural rearrangements of the Y chromosome are associated with male infertility or sterility (Dhanoa, Mukhopadhyay, & Arora, ).…”

“…It is known from human studies that structural rearrangements of the Y chromosome are associated with male infertility or sterility (Dhanoa, Mukhopadhyay, & Arora, 2016).…”