INV DUP(15) - CONTRIBUTION TO THE CLINICAL DEFINITION OF PHENOTYPE

One of the primary goals in medical genetics is a precise clinical def inition of chromosomal diseases. This is now possible because of the i ncreased number of case reports and new techniques. A male patient, wi thout a clear-cut syndrome, was cytogenetically investigated. Chromoso mal analysis showed a small unidentified bisatellited supernumerary ma rker. In situ hybridization with a biotin-labeled DNA probe for the ch romosome 15 centromere (D15Z1) demonstrated that the marker was derive d from chromosome 15. Hybridization with the Prader-Willi Syndrome Cos mid biotinylated probe (localized to band 15q11-q13) showed a signal o n both ends suggesting a marker with a symmetrical inv dup(15) and a b reakpoint localized in q13. It was then possible to define the karyoty pe as: 47,XY, + inv dup(15) (pter-q13::q13-pter). All cases of inv dup (15) reported in the literature were reviewed, paying particular atten tion to the different breakpoints involved, in order to provide a bett er clinical definition of this syndrome.