The human autosomal gene DAZLA: testis specificity and a candidate for male infertility

The DAZ (Deleted in AZoospermia) and DAZLA (DAZ-like autosomal) genes maybe determinants of male infertility. The DAZ gene on the long arm of thehuman Y chromosome is a strong candidate for the 'azoospermia factor'(AZF). Its role in spermatogenesis is supported by its exclusive expressionin testis, its deletion in a high percentage of males with azoospermia orsevere oligospermia, and its homology with a Drosophila male infertilitygene boule. No DAZ homologous sequences have been found on the mouse Ychromosome. Instead, a Dazla gene was isolated from mouse chromosome 17 andhas been considered to be a murine homologue of DAZ. However, the homologybetween human DAZ and mouse Dazla is not strong, and Dazla contains onlyone of the seven DAZ repeats found in DAZ. We report the isolation of thehuman DAZLA gene by screening a human testis cDNA library with a DAZ cDNAclone. DAZLA encodes only one DAZ repeat and shares high homology with themouse Dazla, indicating that these two genes are homologues. Using a panelof rodent-human somatic cell lines and fluorescence in situ hybridization,the DAZLA gene was mapped to 3p24, a region not known to share homologywith mouse chromosome 17. The DAZLA gene may be involved in some familialcases of autosomal recessive male infertility.