Chromosome 15 maternal uniparental disomy and psychosis in Prader-Willi syndrome.

MATERIALS AND METHODS Fifty-nine PWS patients with the diagnosis confirmed by DNA methylation testing had regular and long term follow up at the Centre for Human Genetics in Leuven. For more then 10 years, these patients have been seen at least once a year by a clinical geneticist and a psychiatrist skilled in the assessment of people with learning disabilities. Detailed information on clinical and psychiatric history was recorded in the medical files for all patients. For the past two years all patients were offered a DNA methylation test using probes PW71B and KB17 and FISH analysis for 15q11-12 deletion detection. If FISH analysis did not show a deletion, blood samples were taken from the parents to test for uniparental disomy. If no uniparental disomy was found, an imprinting centre deletion was examined (Essen, Germany).