Duchenne Muscular Dystrophy Newborn Screening: Evaluation of a New GSP® Neonatal Creatine Kinase-MM Kit in a US and Danish Population

Figure 1. The stability of CK-MM in dried blood spot (DBS) specimens stored in a freezer (−20 °C) for a long period of time (years) presented as population median by storage time. A total of 120 sample results per time-point. Dotted line represents the median value of first timepoint.

Figure 2. CK activity (U/L) box plot (a) and CK-MM concentration (ng/mL) box plot (b) of presumed negative (n = 700) and confirmed positive newborn specimens (n = 19) from US population. The highest Duchenne affected samples had CK-MM concentrations above the measuring range of the assay (6.8 to 8000 ng/mL). CK-MM concentration (ng/mL) box plot (c) present the presumed negative (n = 1408) and confirmed positive newborn specimens (n = 16) from Danish population. CK-MM concentration was not elevated in one Duchenne positive sample taken from and preterm newborn with low birth weight (Danish population).

Figure 3. CK-MM concentration (ng/mL) of distribution of presumed negative (n = 1408) and confirmed positive newborn specimens (n = 16). CK-MM concentration was not elevated in one Duchenne positive sample taken from and preterm newborn with low birth weight (Danish population).

Figure 4. CK-MM concentration (ng/mL) by age (unaffected samples from US and Danish populations).

Figure 5. CK-MM concentration (ng/mL) by gestational age (unaffected samples from Danish population).