Table 3.

Serum CK Concentration and Muscle Biopsy Findings in the Congenital Muscular Dystrophies Discussed in Table 1

DisorderSerum CK
Concentration 1		Muscle Biopsy
HistologyImmunohistochemistry
Defects of structural protein
Laminin alpha-2 deficiency (MDC1A)Variable CK from mildly elevated to markedly elevated (before muscle wasting is severe)Neonatal: myopathic or dystrophic w/or w/out inflammatory changes
  • Merosin: partial or total deficiency 2
  • Laminin alpha-5: overexpression
End stage: dystrophic changes
Collagen VI-deficient CMDNormal or mildly elevated (~2-3x normal)Fiber size variationCollagen VI:
  • Variable reduction in muscle
  • Abnormal secretion in fibroblast culture
  • Deficiency difficult to detect if partial 3
Variable necrotic or regenerative fibers
Variable endomysial fibrosis
Defects of glycosylation
DystroglycanopathiesElevated: 2-15x normalMyopathic or dystrophic
  • Merosin: normal or reduced
  • Glycosylated alpha dystroglycan: deficient
  • Beta dystroglycan: normal
Defects of proteins of the endoplasmic reticulum
SELENON (SEPN1)-related CMDNormalVariable fiber sizeMerosin & collagen VI: normal
Occasional necrotic fibers
Minimally increased endomysial connective tissue
Defects of nuclear envelope proteins
L-CMD2-5x normalDystrophic changes (deltoid> quadriceps)
  • Merosin: normal
  • Alpha-dystroglycan: possible secondary abnormal expression
Nonspecific myopathic changes (quadriceps)
Markedly atrophic fibers, most often type 1, occasional positive inflammatory markers
1.

Normal serum CK concentration = 35-160 µ/L (may vary slightly in different laboratories)

2.

Ideally using antibodies recognizing different regions of the protein

3.

May need co-staining with merosin, perlecan, or other proteins to demonstrate abnormal sarcolemmal staining of collagen VI

From: Congenital Muscular Dystrophy Overview – RETIRED CHAPTER, FOR HISTORICAL REFERENCE ONLY

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