Yq microdeletions and their current status in relation to Indian and Global scenario associated to male infertility: A mini appraisal

Abstract

he Y chromosome has a definite role in sex determination and maintenance of male fertility in addition to other processes. The q arm of the Y chromosome contains the azoospermia factors (AZF) region distributed in the q long arm of it at 11, 21, 22, and 23 levels called AZF a, b, and c subregions which are often deleted in infertile cases [1]. The roles of this AZF region in spermatogenesis and male infertility have recently been reviewed [2][3][4]. The region contains three subregions AZFa, AZFb, and AZFc. The AZFa locus contains in proximal Yq extends 1.1 Mb encoding single-copy genes that have X chromosome homologs. Overall AZFa has 15 genes, of which three are protein-coding (DOX3Y, UTY, and USP9Y), one is a testicular-specific transcriptome unit (TTY15), and 11 are pseudogenes (Fig. 1). The AZFb region is located in the central region of Yq 11 and spans 3.2 Mb containing three single-copy regions, a Y chromosome-specific 19 satellite DNA repeat array (DYZ), and 14 multi-copy sequence units amplicons which are highly identical segmented duplications [1,5,6].The AZFc contains 132 genes, of which 15 are protein-coding, 17 are non-coding RNA's, and 100 are pseudogenes. Among 15 protein-coding genes, there are six copies of RBMY, two copies of PRY, two copies of HSFY, one copy each of EIPIAY, KDM5D, CDY2A, RPS4Y2, and XKRY. The AZFc locus is distal to AZFb and is the most complex type and detectable region in infertile men. This locus is 4.5 Mb long containing 97 genes. Among 11 are protein-coding, 10 are non-coding RNA's and 76 are pseudogenes. Among the 11 protein-coding genes, three are four copies of DAZ, three copies of BPY, and two copies each of CDY1 and CS PG-4LY. This region also contains seven testicularspecific transcription factors [2,7] (Fig. 1). METHODOLOGYGenomic DNA was used for analyzing microdeletions with sequence-tagged sites (STS) based on polymerase chain reaction (PCR) technologies. Thus, we describe these AZF deletions by