Male carriers of balanced reciprocal translocations in Northeast China: sperm count, reproductive performance, and genetic counseling

Abstract

ABSTRACT. Balanced chromosomal translocations in men can cause failure of spermatogenesis owing to meiotic impairment. Male carriers may exhibit normozoospermia, although clinical manifestations can include oligozoospermia or azoospermia, oligozoospermia or normozoospermia. Here, we reported the characteristics of balanced reciprocal translocations in men from northeastern China, and explored the relationship between sperm count and reproductive performance, to enable informed genetic counseling. The frequency of balanced reciprocal translocations was found to be 1.62%. Semen analysis showed that 5.9% of male carriers had azoospermia, 43.1% had oligozoospermia, and 51.0% had normozoospermia. Of the 25 men with a balanced reciprocal translocation and azoospermia or oligozoospermia, chromosome 1 was the most commonly often involved in the translocation. However, in the 26 normozoospermic men with a balanced reciprocal translocation and normozoospermia, chromosome 3 was most commonly implicated. Fifty percent of men with a balanced reciprocal translocation conceived a pregnancy that went to term. Our data suggest that of all chromosomes, Reciprocal translocations in northeastern Chinese men 18793©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 14 (4): 18792-18798 (2015) chromosomes 1 and 3 are the most commonly involved chromosomes in balanced reciprocal such translocations in northeastern Chinese men. Karyotype analysis should be performed for men with azoospermia, oligozoospermia, and those in couples having suffered recurrent miscarriages. Natural conception should be discussed during genetic counseling for male carriers of balanced chromosomal translocations with normozoospermia.

Balanced reciprocal translocation at amniocentesis: cytogenetic detection and implications for genetic counseling

“…Frequency rates have been reported to range from 0.08 to 0.3% in the general population (Zhang et al, 2015a). Carriers of balanced chromosomal translocations may be phenotypically normal, but are associated with an increased risk of pregnancy loss, fetal death, and the transmission of chromosomal abnormalities to their offspring through the production of a higher number of unbalanced spermatozoa (Godo et al, 2013).…”

Reproductive outcome of male carriers of chromosomal abnormalities: multidisciplinary approach for genetic counseling and its implications

“…Male carriers of chromosomal abnormalities have often been found to be azoospermic or oligozoospermic (Naasse et al, 2015;Zhang et al, 2015b). Although balanced chromosomal forms exert no phenotypic effect on the carriers, they show variable influence on sperm counts, which can range from normal counts to oligozoospermia or even result in a total absence of sperm in the ejaculate (Zhang et al, 2015c). Hence, reproductive outcomes of the carriers often show normal fertility or infertility.…”

SYCP2translocation-mediated dysregulation and frameshift variants cause human male infertility

“…While it is generally thought that balanced reciprocal translocations may reduce fertility due to production of unbalanced gametes 13 or meiotic silencing of unsynapsed chromatin 45 , this does not account for the specific phenotype of severe oligozoospermia or azoospermia because the majority of men with balanced reciprocal translocations have normal sperm counts 46 . In addition, men with low sperm counts and a balanced reciprocal translocation have rearrangement breakpoints that sometimes cluster in distinct genomic regions, suggesting that as opposed to a nonspecific mechanism of meiotic segregation, there may be something intrinsic to these genomic regions important for fertility 47,48 .…”