Developing New Methods of Supplemental Newborn Screening
Mayo's Biochemical Genetics Laboratory is continuously developing new methods that either improve accuracy or further expand the spectrum of identifiable disorders. For example, screening for congenital adrenal hyperplasia (CAH) is in place in 40 states at this time. The remaining states do not screen for this inherited endocrinopathy because the available immunoassays (i.e., fluorescent immunoassay) for the determination of 17-alpha-hydroxy progesterone (17OHP) have a poor positive predictive value. This causes approximately 200 false-positives for each truly abnormal result, which translates into a significant financial burden on the health care system. More importantly, it causes unnecessary blood draws for the babies tested and emotional stress for the involved families. To improve the positive predictive value, the BGL in collaboration with Mayo's Endocrine Laboratory recently developed a new MS/MS based method for the determination of 17OHP and other relevant steroids. Retrospective testing of more than 700 blood spots indicates an improvement of the positive predictive value from 0.5% to higher than 50%. This steroid analysis is included in Mayo's test offerings.
In the future, additional inherited diseases (i.e., congenital disorders of glycosylation) that can be diagnosed by MS/MS methods will become part of Mayo's Supplemental Newborn Screen.