Prader-Willi syndrome with chromosome 15 interstitial deletion: report of one case.

We report one classical case of Prader-Willi syndrome, and show the specific chromosome number 15 interstitial deletion. This one and half year old boy had the typical face of Prader-Willi syndrome and its characteristic histories of hypotonia, poor feeding, poor growth during early infancy, and then improved appetite and growth since the later half infancy. He also had bilateral cryptorchism and hypogonadism. With an aid of high resolution chromosomal banding technique, we found a small deletion including band 11 to 13 of the long arm of one of his chromosome number 15. This kind of chromosomal aberration is frequently found in Prader-Willi syndrome. This is the first case of Prader-Willi syndrome with chromosomal changes we found in Taiwan. Chromosomal changes may help both the diagnosis and the understanding of etiologies of many disease. We hope the ability to detect small chromosomal lesions will initiate our study to those hereditary diseases.