Validation and Implementation of MPS II Newborn Screening in Missouri Using a Fluorimetric Assay

This poster was presented at APHL NBSGTS 2019 in Chicago, IL.

Authors: T. Klug and H. Bilyeu, Missouri State Public Health Laboratory, Jefferson City, MO

Mucopolysaccharidosis Type II (MPS II), also known as Hunter syndrome, is a lysosomal storage disorder (LSD) caused by a deficiency of the lysosomal enzyme iduronate-2-sulfatase (IDS). MPS II satisfies all criteria for inclusion in the Recommended Uniform Screening Panel (RUSP), with the exception that minimal prospective population screening data are available.

The Missouri State Public Health Laboratory validated a fluorimetric assay for measurement of IDS activity in newborn dried blood spot specimens that requires minimal hands-on time and an incubation time of 2 hours. Results of these validation studies demonstrate robust analytical performance and significant separation between the affected and presumptive normal populations. Four months of population testing have demonstrated a low failure rate, retest rate, and referral rate.

Our studies demonstrate that the IDS fluorimetric assay is a simple, specific, time- and cost-effective method to screen for MPS II. The IDS assay clearly discriminates between healthy and affected samples and shows little to no clinical overlap between the populations. The rate of sample failures (<0.1%), samples requiring retest (<0.15%), and samples requiring 2nd tier / follow-up (<0.015%) are well within acceptable ranges.