Can you tell me the tests and methods of determining a prader willi diagnosis?

DNA test : Micro deletion of genetic material (paternally derived) from chromosome 15 confirms the diagnosis.

3 possible genetic: causes: Most common is a microdeletion in the P-W region of the chromosome 15 from dad. Sometimes both chromosome 15's come from mother or both genes act as if they came from mom because the gene from dad is altered. Tests: FISH test of chromosome 15 in the P-W region or Chromosomal Microarray. Methylation studies show if both genes act as if they came from mom if the CMA is negative.