Common trisomy mosaicism diagnosed in amniocytes involving chromosomes 13, 18, 20 and 21: karyotype–phenotype correlations

✍ Scribed by Robert Wallerstein; Ming-Tsung Yu; Richard L. Neu; Peter Benn; Catherine Lee Bowen; Barbara Crandall; Christine Disteche; Roger Donahue; Betty Harrison; Douglas Hershey; Rodney R. Higgins; Lauren S. Jenkins; Colleen Jackson-Cook; Elizabeth Keitges; Gabriel Khodr; C. C. Lin; Frederick W. Luthardt; Lorraine Meisner; Gregory Mengden; Shivanand R. Patil; Maria Rodriguez; Leonard J. Sciorra; Lisa G. Shaffer; Gail Stetten; Daniel L. Van Dyke; Hungshu Wang; Fran Williams; Ann-Leslie Zaslav; Lillian Y. F. Hsu

• Book ID: 101236582
• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 450 KB
• Volume: 20
• Category: Article
• ISSN: 0197-3851
• DOI: 10.1002/(sici)1097-0223(200002)20:2<103::aid-pd761>3.0.co;2-k

✦ Synopsis

Karyotype±phenotype correlations of common trisomy mosaicism prenatally diagnosed via amniocentesis was reviewed in 305 new cases from a collaboration of North American cytogenetic laboratories. Abnormal outcome was noted in 10/25 (40%) cases of 47,+13/46, 17/31 (54%) cases of 47,+18/46, 10/152 (6.5%) cases of 47,+20/46, and in 49/97 (50%) cases of 47,+21/46 mosaicism. Risk of abnormal outcome in pregnancies with less than 50% trisomic cells and greater than 50% trisomic cells were: 26% (4/15) versus 60% (6/10) for 47,+13/46, 52% (11/21) versus 75% (6/8) for 47,+18/46, 4.5% (6/132) versus 20% (4/20) 47,+20/46, and 45% (27/60) versus 59% (22/37) for 47,+21/46. Phenotypically normal liveborns were observed with mean trisomic cell lines of 9.3% for 47,+13/46, 8.6% for 47,+18/46, 27% for 47,+20/46, and 17% for 47,+21/46. Cytogenetic con®rmation rates were 46% (6/13 cases) for 47,+13/46 mosaicism, 66% (8/12 cases) for 47,+18/46, 10% (10/97 cases) for 47,+20/46, and 44% (24/54 cases) for 47,+21/46. There were higher con®rmation rates in pregnancies with abnormal versus normal outcome: 50% versus 44% for 47,+13/46 mosaicism, 100% versus 33% for 47,+18/46, 66% versus 7% for 47,+20/46, and 55% versus 40% for 47,+21/46. Repeat amniocentesis is not helpful in predicting clinical outcome. It may be considered when there is insuf®cient number of cells or cultures to establish a diagnosis. Fetal blood sampling may have a role in mosaic trisomy 13, 18, and 21 as the risk for abnormal outcome increases with positive con®rmation: 1/5 (20%) normal cases versus 5/8 (62%) abnormal cases. High resolution ultrasound examination(s) is recommended for clinical correlation and to facilitate genetic counselling.