Evaluation of Chromosomal Analyses done on the Parents with Chromosomal Anomalous Children and Recurrent Abortion

ABSTRACT

PURPOSE: To gather reference data for better genetic counseling, we have evaluated the outcomes of chromosomal analyses performed on the parents with chromosomal anomalous children and recurrent abortion in this hospital for the last 20 years. METHODS: Subjected to study were 108 parents (50 fathers & 58 mothers) who had children with Down syndrome, other chromosomal and congenital anomalies, and those who had experienced frequent miscarriages from March 1974 through August 1994. The Moorhead's method with G banding technique was used. RESULTS: 1) Of those 108 parents studied, 52 (48.1%) had Down babies, 27 (25.0%) had frequent miscarriages or stillbirths, 22 (20.4%) had children with congenital anomalies, and 7 (6.5%) had other chromosomal anomalies. 2) Abnormal karyotypes were detected in 9 (8.3%) 6 among 52 parents with Down babies (11.5%), 1 out of 7 parents whose children had other chromosomal abnormalities (14.2%), and 2 from 27 who had experienced miscarriages (7.4%). 3) Abnormal karyotypes of the parents who had Down babies were balanced 14q21q translocations in 2 mothers and 1 father, balanced 21q21q translocation in a carrier mother who looked like Down's, and 14q+ in a normal-looking father. Among the parents having babies with anomalies other than Down's, one mother who gave births to 2 babies, one with balanced and the other with unbalanced translocation, was found to carry t(12;13) balanced translocation. Two women who had experienced frequent miscarriages were found to have balanced 14q21q translocation in one and XXq- in the other. 4) Abnormal karyotypes detected in 6 among those 52 parents with Down babies were 3 out of 38 whose babies had 21-trisomy (7.9%), 2 among 8 parents having babies with 14q21q translocation (25%), and one from 6 parents whose babies had 21q21q translocation (16.7%). 5) Out of 375 Down children, 3 had Down sibling, with the overall recurrence rate of 0.8%, and 2 out of 6 parents of those 3 families were revealed to be balanced translocation carriers. CONCLUSIONS: The high incidence of carrying chromosomal anomaly among the parents having chromosomal anomalous children, but otherwise normal-looking, advocates it essential to have the parents analyzed for their chromosomal make-ups in order to provide better genetic counseling to those who gave birth to a baby with chromosomal abnormality or experienced frequent miscarriages.