Abnormal chromosome in Prader-Willi syndrome.

A Prader-Willi Syndrome (PWS) patient was found to have an extra satellite chromosome, smaller than the normal Chromosome 22, in 60% of her metaphases. G- and C-bandings showed that the extra chromosome did not derive from a Chromosome 15 as has been reported in some PWS patients. Because of variation in chromosomal abnormalities in the PWS patients reported, it was concluded that the chromosomal abnormalities found in them may be a secondary phenomenon rather than the cause of PWS.