Viability thresholds for partial trisomies and monosomies. A study of 1,159 viable unbalanced reciprocal translocations

摘要

From a data base of 1,590 independent families with autosomal reciprocal translocations, 1,159 viable unbalances were studied and the lengths of their trisomy/ monosomy segments measured according to the method proposed by Daniel. About 5 of cases were found not to comply with Daniel viability criteria. The thresholds of viability vary with the mode of unbalance and with the sex of the carrier. Thus, new viability criteria are proposed as a guide for genetic counseling and prenatal diagnosis.