Phân tích nhiễm sắc thể ở ba gia đình sinh con down liên tiếp với kiểu gen người mẹ thể khảm

Down syndrome (trisomi 21) is most frequently observed in chromosomal aberration syndrome and occurs 1 in 600-800 live births. Objective of the study was to analyse chromosome of Down children and chromosome of parents and to consel reproductive risk for these couples. The results showed that three fathers had normal karyotype (46,XY). Two mothers had mosaic karyotype: 47, XX,+21[3percent]/46,XX[97percent], one mother had mosaic karyotype: 47, XX,+21 [4percent]/46,XX[96percent] and karyotypes of Down children were 47, XY,+21. These couples should be counseled about the reproductive risks.