Life without leptin

摘要

The detailed study of nature's experiments on humans has an impressive track record in the field of physiology. In previous centuries such studies usually required a bizarre injury to expose the previously concealed organs of an unfortunate patient to the eyes of a curious physician. But in the late twentieth century we can observe illuminating accidents that occur at the level of DNA. The power of this approach is exemplified by two studies of the fat-derived hormone leptin, one by Clement et al.1 reported on page 398 of this issue, and the other by Strobel et al.2 in Nature Genetics. By studying adult humans who are genetically deficient in leptin signalling, the authors show that leptin is needed for the initiation of puberty and establishment of secondary sexual characteristics. These studies also support the idea that leptin is central to the control of body fat mass in man, and provide more information about other neuro-endocrine and metabolic sequelae of human leptin deficiency.