[Gamete donor karyotyping: between real usefulness and safety rules]

The Commission de génétique de la Fédération française des CECOS has recently sent a questionnaire to each CECOS asking for the year of activity starting, the number of karyotypes performed every year, the number and the type of chromosomal abnormalities and the consequences for the donation process. For sperm donors, 9410 karyotypes have been realized during a mean number of 21.3 years. Fifty-seven chromosomal abnormalities (0.6%) have led to the exclusion of the donors, twenty of which being directly dangerous for the offspring [eight t(13;14), three reciprocal translocations, two structural abnormalities of unknown origin and seven inversions]. Twenty-three anomalies (three supernumerary markers, five 47,XYY, five fragile sites and ten mosaicism) as well as nine other (three Y chromosome inversions and six pericentric inversions of chromosome 9), although considered either as innocuous or as chromosomal variants, have also been excluded. Lastly, five miscellaneous abnormalities have also been considered as exclusion factors. Familial data and sperm counts were known for 28 of these donors. For egg donors, only 681 karyotypes have been performed during a mean number of 7.8 years of activity. Five karyotype abnormalities have led to the exclusion of the donor: one 47,XXX, one mosaicism 45,X/47,XXX/46,XX, one case of non specific rearrangements in half of mitosis and two reciprocal translocations [t(8;20) (q13;p13) et t(3;17) (q26;p13)]. The consequences of this study on gamete donor genetic screening are discussed.