A child, aged 6 years 3 months, with a triglyceride storage disorder in peripheral adipose tissue, microcephaly, and gross emaciation has been studied at autopsy. The mean triglyceride content of adipocytes in hand and foot was 0.17 +/- 0.02 mug/cell and 0.18 +/- 0.02 mug/cell. Adipocytes from abdominal tissue were small, irregular, and difficult to measure accurately, reflecting the degree of cachexia. Basal tissue contents of cyclic AMP and release of glycerol and fatty acid from peripheral tissue of the child were in the same range as adult tissues. None of these measurements, however, were increased by incubation with isoprenaline (10(-5 M), compared to a three- to seven-fold increment in adult subcutaneous tissues and to a four- to ten-fold increment of glycerol and cyclic AMP in peripheral adipose tissue of a control child aged 10 years. We postulate that the proband may have had a defect of adenyl cyclase or catecholamine receptor, which has a role in the abnormal storage of triglyceride in peripheral adipose tissue.