Abstract:

Objective To evaluate the feasibility of creatine kinase isoenzyme MM（CK-MM） in neonatal Duchenne muscular dystrophy（DMD） screening. Methods Totally,7 035 dried blood spots of male newborns were collected. CK-MM was determined by time-resolved fluorescence method,and the positive results was determined by DMD gene determination further. The performance（accuracy,precision,linear range and so on） of CK-MM determined by time-resolved fluorescence method was verified. The efficiency of CK-MM in screening DMD was evaluated by receiver operating characteristic（ROC） curve. Results The within-run coefficient of variation（CV）,the between-run CV and average bias of CK-MM determined by time-resolved fluorescence method were <10%. The linear regression equation was Y= 1.045 8X+1.929 6（r=0.999 9,P<0.01）. The concentration of CK-MM in children with DMD was higher than that in healthy control group（P<0.000 1）,which was 67 times higher than that of healthy control group. Among the 7 035 male newborns,6（0.085%） cases were positive after screening,and 2 cases were confirmed. DMD gene determination results showed that all of them were hemizygous mutation,and their genotypes were c.1990C>T（p.Gln664*）and c.7657C>T（p.Arg2553*）. ROC curve analysis showed that the area under curve（AUC） of CK-MM for the diagnosis of DMD was 1.0,the optimal cut-off value was 762 ng/mL,the sensitivity was 100%,and the specificity was 99.94%. Conclusions Using dried blood spots to determine CK-MM can effectively screen the children with DMD,and this method is simple and worthy of clinical application.

Key words: Creatine kinase isoenzyme MM, Duchenne muscular dystrophy, Dried blood spot