RATES OF MUTANT STRUCTURAL CHROMOSOME REARRANGEMENTS IN HUMAN FETUSES - DATA FROM PRENATAL CYTOGENETIC STUDIES AND ASSOCIATIONS WITH MATERNAL AGE AND PARENTAL MUTAGEN EXPOSURE

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  • 1 January 1983
    • journal article
    • research article
    • Vol. 35  (1) , 96-109
Abstract
In 27,225 prenatal cytogenetic studies of amniotic fluid reported to the New York State Chromosome Registery and the United States Interregional Chromosome Register System (USA), there were 61 cases with a structural chromosomal abnormality not known inherited, a rate per 1000 of 2.24. Of these 33, 1.21/1000 were known de novo and nonmosaic; consequently, the rate of events resulting from germinal mutation is highly likely to be between these 2 limits. The rates per 1000 of unbalanced abnormalities were 0.59-1.29; of balanced abnormalities, 0.62-0.96; of balanced Robertsonian translocations, 0.22-0.29; and of unbalanced Robertsonian translocations, 0.07-0.11. The rates of fetuses with supernumerary markers and fragments were unexpectedly high: 0.26-0.70/1000. These abnormalities were associated with increased maternal age (38.0 .+-. 5.4 to 38.4 .+-. 3.6 compared to 35.6 .+-. 4.3 in controls), but even after adjustment for the bias to preferential study of older women, the observed rates of these supernumerary abnormalities were greater than would be expected from live-birth studies or rates estimated in all recognized conceptuses. These were trends to elevated maternal age for the group of all balanced rearrangements, and to diminished maternal age for the nonsupernumerary, non-Robertsonian unbalanced rearrangements. In 136 women studied primarily because of exposure to a putative mutagen, a de novo deletion and an inversion not known inherited were detected. The rate of abnormality in these 136, 1.47%, was significantly greater than the rate of abnormality in the remainder: 0.14-0.22%.