(1) Centro di Genetica Umana, Centro Studi Regionale sulla Sindrome di Down, E.O. Ospedali Galliera, Via A. Volta, 6, I-16128 Genova, Italy;(2) Laboratory of Molecular Oncology, National Cancer Institute, 21701 Frederick, MD, USA
Abstract:
Summary The precise origin of the supernumerary chromosome can be defined in the majority of trisomy 21 cases. This is achieved by evaluating the chromosome 21 short arm polymorphism and analysing restriction fragment length polymorphisms (RFLPs) of multiple chromosome 21 loci. We report a study on 37 Italian families with Down's syndrome. In 35 cases (94.6%) both the parental and the meiotic stage of non-disjunction could be established. Knowledge of the origin of the extra chromosome 21 is a pre-requisite for investigations of genetic or environmental factors that may affect the meiotic process.