Endocrine abnormalities and myopathy in Bloom's syndrome.

Abnormal endocrine indices and myopathy have been variably present in two brothers with Bloom's syndrome (congenital teleangiectatic erythema, hypersensitivity to light, and growth retardation). These consisted of: (1) growth retardation with height and weight below the third centiles; in the younger one at age 14, hypoglycaemia failed to elicit a rise in growth hormone but did so in the older one at age 17; (2) serum TSH was raised in the older one in whom serum FSH and LH were also above the normal range; and (3) myopathy characterised by pronounced dilatation of the sarcoplasmic reticulum was present in the younger one; distinct reduction of muscle strength was shown in his older brother with ultrastructural alteration of skeletal muscle of unknown significance.