[Rapid prenatal diagnosis of chromosome abnormalities: from FISH to QF-PCR].

Prenatal diagnosis for pregnancies at increased risk for chromosome abnormalities is routinely undertaken by karyotype analysis. While karyotype analysis remains the standard method to detect structural and copy number changes of chromosomes, it requires prolonged cell culture resulting in average reporting times of about two weeks. To relieve parental anxiety, and improve the quality and plasticity of pregnancy management, rapid methods, such as FISH and QF-PCR have recently been developed.

Familial translocation t(Y;15)(q12;p11) and de novo deletion of the Prader-Willi syndrome (PWS) critical region on 15q11-q13.

We describe a 17-year-old girl with mild Prader-Willi syndrome (PWS) due to 15q11-q13 deletion. The deletion occurred on a paternal chromosome 15 already involved in a translocation, t(Y;15)(q12;p11), the latter being present in five other, phenotypically normal individuals in three generations. This appears to be the first case of PWS in which the causative 15q11-q13 deletion occurred on a chromosome involved in a familial translocation, but with breakpoints considerably distal to those of the familial rearrangement.

de novo inversion-duplication of 2q35-2qter without growth retardation.

A 7-year-old mentally retarded child was found to be the carrier of a de novo inversion-duplication of 2q35-2qter. His phenotype corresponded to that which is classically described in cases of partial trisomy of the long arm of chromosome 2; however, he did not show the growth retardation which usually characterizes this and other aneuploidy syndromes.