Down syndrome with partial trisomy of chromosome 21 because of a de-novo unbalanced translocation t(13;21)(q10;q22)

摘要

Trisomy 21, affecting 1/800 live births, is the most frequent and most studied aneuploidy. Five percent of trisomy 21 results from translocation. Partial trisomy 21 is very rare, less than 1% of Down syndrome, often caused by an imbalance of a parental balanced translocation (Turleau and Vekemans, 2010). Recent advances in cytogenetic techniques allow enhanced diagnosis and a better understanding of these anomalies. We observed a 12-month-old boy with a partial trisomy 21 related to a de-novo unbalanced translocation of a small segment of chromosome 21, with a typical clinical phenotype of Down syndrome.