Objective: To evaluate the occurrence and prevalence of microdeletions of the Y chromosome involving the DAZ (Deleted in AZoospermia) gene in patients with azoospermia or severe oligozoospermia.
Design: Controlled clinical study.
Setting: University infertility clinic.
Patient(s): Infertile men (n = 168) with nonobstructive, idiopathic azoospermia or severe oligozoospermia and normal LH. The control group consisted of proven fathers (n = 86).
Intervention(s): None.
Main outcome measure(s): Semen analysis; polymerase chain reaction amplification of the loci sY84, sY143, sY254, and sY255; serum FSH, LH, and T; testicular volume.
Result(s): Deletions involving the sY254 and sY255 DAZ loci were found in three azoospermic patients and two men with sperm concentration < 1 x 10(6)/mL. Serum FSH was elevated in four patients and was normal in one. All five patients had decreased testicular volumes compared with controls. No deletions involving the sY84 and sY143 loci were found. The four loci were amplified normally in the control group.
Conclusion(s): The estimated frequency of deletions involving the DAZ locus is 3% in azoospermic-severely oligozoospermic men consulting an infertility clinic. Polymerase chain reaction amplification of the DAZ locus is useful for the diagnosis of microdeletions of the Y chromosome. Deletions involving more proximal regions of the Y chromosome seem to be rare.