THE ROLE OF PARCIAL AZFC MICRODELETIONS ON THE SEX-RATIO OF CHILDREN BORN TO FERTILE MEN OF JAPANESE ORIGIN IN BRASIL: REGULATION OF SECONDARY SEX-RATIO MAY ALSO BE INFLUENCED BY GENETIC FACTORS

Abstract

Introduction: Deletions of the human azoospermic factors (AZFa, AZFb, AZFc) located on the Yq chromosome are one of the main causes of male infertility. Complete AZFc deletion is the most frequent worldwide but the effect of partial AZFc deletions are yet to be fully understood. Methods: We first performed a first round screening for classical AZFc microdeletion in 223 Japanese-of-origin men using STSs sY254, followed by PCR using specific STSs (G73166-MboI; G73168-AluI; G73167-FspI) and restriction analysis (2U overnight at 37o C) directed to the SNVs that characterize each specific DAZ copy (Fernandes et al. 2002). Results: No partial deletion (del-) was identified in 28 (12.6%) men; deletion of DAZ4 (del4) was found in 120 (53.8%) men and of DAZ1/DAZ2/DAZ3 (del123) in 75 (33.6%). The three groups showed similar mean number of children (del- 2,07; del4 2.13; del123 1.93) and sex-ra-tio (del- 1.23; del4 1.21; del123 0.93). The highest sex-ratio was found in the spring time (del- 1.88; del4 1.68; del123 1.44) and the lowest in the summer with a significant difference (p<0.05) for the del123 group (del- 0.91; del4 0.96; del123 0.56). Conclusion: Partial AZFc deletions are frequent in Japan and seasonal differences in sperm count was recently reported (Nakahori et al, 2012). To the best of our knowledge, this is the first report on the influence of Y chromosome microdeletion in the modeling of human populations. We propose a hypothesis according to which AZFc partial deletion, together with environmental factors, may be an important event in regulating the overall fertility of populations by means of lowering the secondary sex-ratio.