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Cockayne syndrome is an autosomal recessive disease, which includes as major features motor and mental retardation (beginning in the second year), microcephaly, ataxia, retinal degeneration and pigmentation, cataracts, progeroid features, intracranial calcification, hypogonadism, and growth retardation. Many other diseases have some of these features, so that diagnosis of Cockayne syndrome can be difficult, especially in younger children. Eccrine sweat glands were microdissected from autopsy or biopsy specimens from patients with Cockayne syndrome, and mean values for duct length, secretory coil volume, ratio of coil volume to duct length, and axis ratio of the secretory coil were determined. In comparison with values for eccrine glands of patients with no known genetic or chromosomal disease, eccrine glands in Cockayne syndrome are abnormally small for age. Whether other diseases with various similarities to Cockayne syndrome produce similar growth abnormality of eccrine sweat glands is not known, but determination of sweat gland size may provide data suggesting or supporting the diagnosis of Cockayne syndrome.

Skeletal muscle fibers isolated from 50 muscle specimens from 10 children with cardiomyopathy of unknown cause are compared to those from 18 specimens from 5 patients with skeletal muscle myopathies, 45 specimens from 18 patients with congenital heart disease, and 15 specimens from 7 patients with no genetic, chromosomal, or cardiac disease. Muscle fibers from the myopathy specimens show increased nuclei/mm of fiber and increased nuclei/mm/micron of diameter (R value), as well as reduced surface area and volume of cytoplasm per nucleus, compared to control values. The values for cardiomyopathy deviate from normal in the same way as, but to a lesser degree than, those for myopathy--namely, in this material, diseases with cardiomyopathy tend also to produce mild myopathy. Since cardiac and skeletal muscle pathologic findings have not been adequately studied for the majority of the approximately 50 genetic disorders causing cardiomyopathy or otherwise affecting cardiac function described to date, the data indicate primarily that skeletal muscle biopsy will undoubtedly be more useful in cardiomyopathic disorders when the appropriate correlative studies of cardiac and skeletal muscle in such diseases have been done. Because larger biopsy specimens can be obtained, skeletal muscle merits further exploitation in biochemical research on basic mechanisms of disorders causing cardiomyopathy.

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