[High-resolution cytogenetic study of a patient with Prader-Willi syndrome].

We investigated a patient with Prader-Willi syndrome by using the high-resolution banding technique. His clinical findings were also examined in some detail. The patient had interstitial deletion of 15q, with breakpoints at 15q11.2 and 15q13. However, he had a normal karyotype at about 400 bands per haploid-set. During the course of this study, it was realized that a small deletion in the proximal 15q could be easily overlooked when a mitotic spread of about 400-bands or less per haploid-set was used. It is suggested that the high-resolution banding technique is of great importance in identifying microdeletions and other microaberrations of chromosomes.