Creatine-kinase (CK) and pyruvate-kinase (PK) activities in cord blood of normal newborn infants: Application to duchenne muscular dystrophy screening programs

Abstract BACKGROUND Duchenne muscular dystrophy (DMD) is a progressive, lethal X-linked neuromuscular disorder with an average worldwide incidence of 1:5000. Blood spot creatine kinase (CK) enzyme assays previously used in newborn screening programs for DMD are nonspecific because measured CK enzyme activity is attributable to 3 isoenzyme forms of CK (CK-MM, CK-MB, and CK-BB) and it is the CK-MM isoform that is found predominantly in skeletal muscle. CK-MM is increased in boys with DMD owing to muscle damage. We describe a sensitive and specific automated immunoassay for CK-MM to screen for DMD in blood spots. METHODS The prototype assay was developed on the PerkinElmer GSP® analyzer to enable high-throughput screening. CK-MM was assayed using a solid phase, 2-site immunofluorometric system. Purified human CK-MM was used to create calibrators and controls. RESULTS The limit of blank (LOB), detection (LOD), and quantification (LOQ) values were <1, 3, and 8 ng/mL, respectively. The analytical measurement range was 4–8840 ng/mL. Interassay (n = 40) imprecision was <7% across the analytical range. Cross-reactivity was <5% for CK-MB and 0% for CK-BB. The mean recovery of CK-MM was 101% (range 87%–111%). Blood spots from newborn infants (n = 277) had a mean CK-MM concentration of 155 ng/mL and a 99th centile of 563 ng/mL. The mean blood spot CK-MM concentration from 10 cases of DMD was 5458 ng/mL (range 1217–9917 ng/mL). CONCLUSIONS CK-MM can be reliably quantified in blood spots. The development of this CK-MM assay on a commercial immunoassay analyzer would enable standardized and high-throughput newborn blood spot screening of DMD.

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Genetic and environmental components of serum creatine kinase (CK) and pyruvate kinase (PK) in normal twins: Implication for genetic risks estimates in Duchenne muscular dystrophy carriers

American Journal of Medical Genetics ◽

10.1002/ajmg.1320310206 ◽

1988 ◽

Vol 31 (2) ◽

pp. 291-298 ◽

Cited By ~ 4

Author(s):

Debora Rapaport ◽

Gloria M. D. D. Colletto ◽

Mayana Zatz ◽

John M. Opitz ◽

James F. Reynolds

Keyword(s):

Creatine Kinase ◽

Duchenne Muscular Dystrophy ◽

Muscular Dystrophy ◽

Pyruvate Kinase ◽

Serum Creatine Kinase ◽

Genetic Risks

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The stability of MM-creatine kinase activity in human fetal plasma — a pitfall in the prenatal diagnosis of Duchenne muscular dystrophy

Clinica Chimica Acta ◽

10.1016/0009-8981(83)90043-8 ◽

1983 ◽

Vol 129 (3) ◽

pp. 379-384 ◽

Cited By ~ 3

Author(s):

Robert J. Edwards ◽

David C. Watts

Keyword(s):

Creatine Kinase ◽

Prenatal Diagnosis ◽

Duchenne Muscular Dystrophy ◽

Muscular Dystrophy ◽

Kinase Activity ◽

Creatine Kinase Activity ◽

Fetal Plasma ◽

The Stability

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Dilution Effect on Serum Creatine Kinase in Carriers of Duchenne Muscular Dystrophy

Annals of Clinical Biochemistry International Journal of Laboratory Medicine ◽

10.1177/000456327901600111 ◽

1979 ◽

Vol 16 (1-6) ◽

pp. 54-55 ◽

Cited By ~ 1

Author(s):

A. C. Simpson ◽

D. Holmes ◽

R. J. T. Pennington

Keyword(s):

Creatine Kinase ◽

Duchenne Muscular Dystrophy ◽

Muscular Dystrophy ◽

Dilution Effect ◽

Serum Creatine Kinase ◽

Normal Female ◽

Female Subjects

Dilution of serum before assay consistently increased the activity of serum creatine kinase both in normal female subjects and in carriers of Duchenne muscular dystrophy.

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