Does the prognosis after PGT for structural rearrangement differ between female and male translocation carriers?

RESEARCH QUESTION: Chromosomal translocations are known genetic causes of premature ovarian insufficiency syndrome. Are certain translocations associated with decreased capacity of small antral follicles to respond to exogenous FSH? Does the prognosis after preimplantation genetic testing for structural rearrangements differ in couples with female or male translocation carriers and according to the type of translocation? DESIGN: A single-centre, retrospective, observational study covering a 10-year period. One hundred and thirty-nine females carrying a translocation were compared with 192 partners of male translocation carriers. To evaluate ovarian response to FSH, the follicular output rate was used, defined by ratio between the pre-ovulatory follicle count on day of HCG x 100/antral follicle count (AFC). To determine a cut-off of metaphase II oocytes and biopsied embryos as predictor of obtaining a balanced embryo transfer, receiver operator characteristic curves were plotted. RESULT: A decreased capacity of small antral follicles to respond to exogenous FSH in female translocation carriers was found. The number of metaphase II oocytes in both groups was weakly informative as a predictor of obtaining an embryo transfer. The number of biopsied embryos had some clinical value, however, and allowed a cut-off of 6.5 to be determined for female translocation carriers versus 5.5 for the partners of male translocation carriers. Live birth rates, however, were not different between female and male translocations carriers. CONCLUSIONS: Female translocation carriers may respond poorly to ovarian stimulation, and present a higher rate of unbalanced embryos, which means that higher gonadotrophin doses may be required to increase the number of biopsied embryos.

Chromosomal translocations and semen quality: A study on 144 male translocation carriers.

RESEARCH QUESTION: Chromosomal translocations are known genetic causes of male infertility. Are certain translocations or chromosomal regions more directly associated with sperm defects? Is there a threshold of sperm impairment that can be relevant for detection of translocations? DESIGN: This is a monocentric retrospective observational study covering a 10-year period. Eighty-one patients carrying a reciprocal translocation (RCT) and 63 carrying a Robertsonian translocation (ROBT) were compared with 105 fertile patients. Semen quality before and after sperm migration was compared. The aims were to define whether a threshold based on sperm analysis could be proposed for detection of translocations and to identify whether some redundant chromosomal regions might be associated with sperm quality defects. RESULTS: The number of progressive spermatozoa retrieved after sperm preparation (NPS-ASP) was altered in both RCT and ROBT carriers compared with controls, with a stronger alteration in ROBT. Based on the NPS-ASP results in this large group of translocation carriers, a relatively robust threshold, fixed at less than 5 million, may be proposed for detection of translocations. The alteration of NPS-ASP was independent of the chromosome involved in ROBT, while in RCT, four redundant chromosomal regions (1q21, 6p21, 16q21, 17q11.2) were associated with poor or very poor NPS-ASP. CONCLUSIONS: The NPS-ASP appears to be a good parameter to assess sperm function and would be a useful tool to detect chromosomal translocations. Four redundant regions have been identified on four chromosomes, suggesting that they may contain genes of interest to study sperm functions.