SEX-RATIO AND ABSENCE OF UNIPARENTAL DISOMY IN SPONTANEOUS-ABORTIONS WITH A NORMAL KARYOTYPE

A series of spontaneous abortions collected in the South Wales region over a period of 18 months was karyotyped to identify those with a nor mal chromosome complement. Microsatellite polymorphisms distributed th roughout all autosomes were typed by the polymerase chain reaction to determine the parental origin of each autosome pair in karyotypically normal spontaneous abortions. In 35 cases biparental inheritance of ev ery autosome pair was demonstrated. The sex ratio of the normal sponta neous abortions of proven biparental origin was 0.77, but this was not significantly different from 1.00.