Genomic analysis of idiopathic infertile patients with sperm-specific depletion of CD46

Three infertile subjects with no expression of CD46 (membrane cofactor prot ein of complement) on their spermatozoa were found when screening 542 idiop athic male infertile patients. The sperm CD46 isoform was reported to be as sociated with the sperm-egg interaction, yet a ubiquitous expression of CD4 6 confers resistance to complement-mediated injury on host cells. All three patients expressed normal CD46 isoforms on their lymphocytes and granulocy tes. Thus, the loss of CD46 is sperm-specific, probably due to testicular g erm cell-specific regulation of CD46 production. Recently, a mechanism of t he gene regulation of human CD46 was elucidated in which the silencer eleme nt of the 3' UT and the promoter region of human CD46 gene partly participa te. Here, we analyzed these regions of the CD46 gene in our 3 patients. We found no abnormality in 3' and 5' regions of the CD46 genome in the 3 patie nts. Thus, in these infertile patients sperm-specific depletion of CD46 is not governed by the so for identified regulators in the CD46 gene. Other un known factors outside the known regulatory regions would play a role in the regulation of sperm-specific CD46 expression. Copyright (C) 2001 S. Karger AG, Basel.