Chromosomal abnormalities in oocyte donor candidates: a French survey of over 8,200 karyotypes

Abstract

Objective: To study karyotypes of >8,200 oocyte donor candidates in nulliparous or multiparous women compared with a reference population.

Design: A retrospective observational multicentric study.

Subjects: The study included 2 cohorts of oocyte donor candidates recruited between January 2005 and October 2021: multiparous women with at least 1 child at the time of recruitment and nulliparous women. Both were compared with a reference population composed of female newborns from literature.

Exposure: Not applicable.

Main outcome measures: Blood lymphocyte karyotype.

Results: A total of 8,229 oocyte donor candidates from 22 fertility centers were included in this study. Nulliparous (n = 1,890) and multiparous (n = 6,339) women were compared with 8,102 female newborns. Overall, 65 candidates were carriers of chromosomal abnormalities and were, therefore, excluded from the donation process (0.79%; 95% confidence interval [CI], 0.60-0.98). The occurrence of balanced structural chromosomal rearrangements globally increased in the study population (0.49%; 95% CI, 0.34-0.64) compared with that in female newborns (0.24%; 95% CI, 0.34-0.64). The number of reciprocal translocations increased fivefold in nulliparous oocyte donor candidates (0.37%; 95% CI, 0.10-0.64). The incidence of sex chromosome mosaicism notably increased in multiparous oocyte donor candidates, with 17 cases (0.27%; 95% CI, 0.14-0.40). Among chromosomal aberration carriers, only 2 nulliparous women (1 reciprocal translocation and 1 sex chromosome mosaicism) had fertility issues with a diagnosis of premature ovarian failure.

Conclusion: In this comprehensive 16-year French experience of karyotyping in oocyte donor candidates, we confirmed an increased incidence of balanced structural chromosomal rearrangements, especially among those without children at the time of recruitment. Karyotyping could be considered to identify any chromosomal abnormalities that may not be easily detectable through medical questioning. These abnormalities pose an inherent genetic risk for gamete recipients if left undetected.

Keywords: Chromosomal abnormalities; genetic testing; karyotype; oocyte donor; translocation.