The Chromosomal Risk in Sperm from Heterozygous Robertsonian Translocation Carriers is Related To the sperm Count and the Translocation Type

Objective: To study the chromosomal risk in sperm from Robertsonian translocation (RobT) carriers as a function of the sperm count and translocation type.

Design: Prospective study.

Setting: Departments of reproductive biology, cytogenetics, gynecology, and obstetrics.

Patient(s): A total of 29 RobT patients (8 normozoospermic and 21 oligozoospermic) and 20 46,XY patients (10 normozoospermic and 10 oligozoospermic).

Intervention(s): Sperm fluorescence in situ hybridization with probes for translocation malsegregation and chromosome 13, 18, 21, X, and Y probes for studying the interchromosomal effect (ICE).

Main Outcome Measure(s): Translocation malsegregation and ICE aneuploidy rates.

Result(s): In RobT carriers, the sperm translocation malsegregation rate was significantly lower in normozoospermic patients (9.7%) than in oligozoospermic patients (18.0%). Considering only oligozoospermic patients, sperm malsegregation rates were significantly lower for rob(14;21) than for rob(13;14) (11.4% vs. 18.9%). In turn, the rates were significantly lower for rob(13;14) than for rare RobTs (18.9% vs. 25.3%). In sperm from normozoospermic RobT, an ICE was suggested by higher chromosome 13 and 21 aneuploidy rates than in control sperm. Conversely, chromosome 13 and 21 sperm aneuploidy rates were lower in oligozoospermic RobT patients than in oligozoospermic 46,XY patients, but higher than in control subjects.

Conclusion(s): Both translocation type and sperm count influence the RobT malsegregation risk. Of the chromosomes analyzed (13, 18, 21, X, and Y), only chromosomes 13 and 21 were found to be associated with an ICE. Relative to the RobT effect, idiopathic alterations in spermatogenesis in 46,XY patients appear to be more harmful for meiosis.