Evaluation of the GSP Creatine Kinase-MM Assay and Assessment of CK-MM Stability in Newborn, Patient, and Contrived Dried Blood Spots for Newborn Screening for Duchenne Muscular Dystrophy

Abstract

Duchenne Muscular Dystrophy (DMD) is a fatal X-linked disorder with a birth prevalence of 19.8:100,000 males worldwide. Elevated concentration of the muscle enzyme creatine kinase-MM (CK-MM) allows for presymptomatic screening of newborns using Dried Blood Spots (DBS). We evaluated imprecision and carryover of the FDA-approved PerkinElmer GSP Neonatal CK-MM kit over multiple runs, days, and operators, followed by quantification of CK-MM loss in stored newborn, contrived, and non-newborn patient DBS resulting from exposure to ambient versus low humidity (50-day trial), and high humidity and high temperature (8-day trial). Imprecision %CV was ≤14% for all verification comparisons and over 6 months of testing. On average, the mean CK-MM recovery after 50 days was >80% of initial concentration for all sample types stored in low humidity and <80% in ambient humidity. After 8 days of storage in high humidity and high temperature, the mean recovery for newborn samples was <80%. Verification results for the GSP Neonatal CK-MM assay were concordant with kit parameters and the assay performed consistently over 6 months. CK-MM degradation in ambient storage can be mitigated by reducing exposure to humidity. Assessment of DBS shipping and storage conditions is recommended prior to implementing DMD screening.

Multi-Laboratory Evaluation of Prototype Dried Blood Spot Quality Control Materials for Creatine Kinase-MM Newborn Screening Assays

“…For NBS programs to establish and sustain DMD screening, laboratories will need reliable access to external QC materials to validate assays, conduct stability studies [ 20 ], ensure the consistency of test results, and meet regulatory requirements [ 15 ]. QC over a wide range is important, since CK-MM levels are variably elevated by birth trauma and then decline in the early post-natal period [ 21 ].…”

Biomarkers in Duchenne Muscular Dystrophy: Current Status and Future Directions

“…More recently, studies have piloted screening with quantitative detection of the CK-MM isoform as a specific biomarker of muscle damage using the FDAapproved GSP neonatal CK-MM kit (#3311-001U, PerkinElmer) [25,26].…”

Newborn screening for Duchenne muscular dystrophy‐early detection and diagnostic algorithm for female carriers of Duchenne muscular dystrophy

“…In December 2019, the FDA approved the first-tier screen kit for DMD, which measures the level of creatine kinase-MM in dried blood spots. The test kit is high throughput and provides a method for universal screening of DMD in newborns (Chien et al, 2022;Ke et al, 2017;Migliore et al, 2022;Moat et al, 2017;Parad, Sheldon, & Bhattacharjee, 2021;Timonen et al, 2019). Data from pilot studies indicate that the assay can also detect other muscular dystrophies (Ke et al, 2017;Timonen et al, 2019) However, the mother, who later identified herself as a carrier, declined to submit another specimen for testing or follow-up.…”

“…Currently in the United States, DMD is not included as a condition on the Recommended Uniform Screening Panel (RUSP), and no states are routinely screening for DMD. However, pilots are underway or recently completed in three states (Hartnett et al, 2022 ; Migliore et al, 2022 ; Parad, Sheldon, & Bhattacharjee, 2021 ), a RUSP nomination package has been submitted, and at least one state is considering adding DMD to their panel. This increase in support for DMD NBS is consistent with an overall movement to more broadly consider this disorder for NBS, recognizing benefits beyond medical treatment, which often includes avoiding a diagnostic odyssey, family planning, and enrollment in early childhood intervention services, as discussed by Chung et al ( 2022 ).…”