The human family of DAZ (D eleted in AZ oospermia) genes consists of a cluster of genes on the Y chromosome and a single autosomal homologue, DAZL1 (DAZ-L ike), that maps to chromosome 3p24. Discovered in a search for Y chromosome genes that cause male infertility, these genes produce proteins found in both the nucleus and cytoplasm of male gonocytes and are abundant in spermatogonia nuclei. At meiosis, both gene proteins relocate to the germ-cell cytoplasm. Little is known about whether DAZL1 might have a role in female fertility, but in mice, loss of function of the homologue of DAZL1 results in the loss of both male and female germ cells. The gene protein in mice is localized to prenatal and postnatal follicles.
Antisera recognizing human DAZL1 were used to study the expression of this gene in female tissues. The antibodies were prepared in rabbits against peptide sequences specific to DAZ/DAZL1 proteins. When the distribution of messenger RNA for DAZL1 was studied using the reverse transcription–polymerase chain reaction technique, the gene was found to be expressed in the ovary and testis but not in heart, liver, or brain tissue. Immunohistochemical studies revealed staining of adult and fetal ovarian sections by both antisera. Staining was most intense in the oocytic cytoplasm of developing follicles in the fetus and adult. The granulosa cells stained weakly for DAZL1 protein.
These findings suggest that the DAZL1 gene is a candidate fertility factor in women. Supportive data come from a study by Ruggiu et al. showing that loss of function of the DAZL1 homologue in mice leads to loss of germ cells in both males and females. It would seem appropriate to seek mutations in this gene in peripheral blood DNA from women who have primary amenorrhea or premature ovarian failure.
Hum Reprod 1999;14:2531–2536