This project will have an assay development phase and an assay validation phase.~In the assay development phase, the investigators will develop a method of assessing SNRPN promoter (located in chromosome 15 q11-q13) methylation status using methylation-specific PCR coupled with a melting curve analysis with de-identified leftover DNA from routine newborn screening dried blood samples for severe combined immunodeficiency and spinal muscular atrophy.~In the assay validation phase, the investigators plan to assess the assay sensitivity and specificity using a set of DNA samples extracted from dried blood spots in each following group:~Healthy individuals~AS patients with genetic testing confirmation that the maternal copy of chromosome 15 q11-q13 is deleted, or that there are two paternal copies of chromosome 15 q11-q13 or imprinting center defect.~PWS patients with genetic testing confirmation that the paternal copy of chromosome 15 q11-q13 is deleted, or that there are two maternal copies of chromosome 15 q11-q13 or imprinting center defect.~For participants with AS or PWS, blood samples will be obtained via a self-administered finger prick performed in the participant's home. The participant will mail the sample to the researchers using a provided envelope. If the team is not able to reach the participant after two phone call attempts, the study team may approach them at their next clinic visit to assess interest in study participation. If participants opt to join the study at this clinic visit, the blood sample may be obtained in clinic.~For healthy controls, blood samples will be obtained via a self-administered finger prick, and participants will verbally respond to a brief demographic questionnaire.
The overall purpose of this project is to establish the capability of screening for Angelman syndrome (AS) and Prader-Willi syndrome (PWS) in public health newborn screening (NBS) programs, with an aim of developing and validating a screening test for AS and PWS.