SNRPN and Prader-Willi syndrome: MS-MLPA will determine the methylation status by using 5 to 6 methylation probes in the SNRPN locus and other imprinted genes close by to confirm the diagnosis of PWS as well as about 30 probes within the 15q11-q13 region that are used with reference (control) probes outside of the region and on other chromosomes to determine the copy number status [21, 22].