6533b7d0fe1ef96bd125acb9

RESEARCH PRODUCT

Cap disease uncapped

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description

With the advent of enzyme histochemistry and electron microscopy, the new nosographic group of congenital myopathies hailed as ‘‘new myopathies’’ [1] was established, largely based on morphological features in biopsied muscle specimens although clinically early (congenital) onset and mild progression were also attributed to these childhood myopathies. When molecular investigations of patients with hereditary neuromuscular diseases began, earlier classifications based on clinical, morphological, and metabolic criteria started to quake, most conspicuously observed in the group of limb girdle muscular dystrophy or limb girdle muscular syndrome, which now comprise seven autosomal dominant (LGMD1A to G) and twelve autosomal-recessive (LGMD2A to L) forms [2]. With the identification of mutations in the ryanodine receptor-1 in central core disease, molecular-based nosographic re-orientation had reached the nosological group of congenital myopathies [3]. Since then, the molecular spectrumof congenitalmyopathies has become broad and diverse [2] with genetic subtyping and overlap among several classical congenital myopathies. In this issue (pages 433–442), Lehtokari and colleagues have added another piece to the genetic mosaic of congenital myopathies by reporting a mutation in the b-tropomyosin gene TPM2 in a patient with morphological and clinical features of ‘‘cap’’ disease. This paper presents several important aspects: (1) It identifies cap disease as a true genetically defined entity. This nosographic significance of a separate type of congenital myopathy had already been suggested in the very first description by Fidzianska and colleagues in 1981 [4] and subsequently reiterated by her in 2002 [5] when she presented three additional unrelated patients, two of them having been adults at