Smith-Magenis Syndrome (SMS) is a rare genetic disorder. Patients with SMS are mentally retarded, not able to control their emotions, they often have hearing and speech impairment and lowered sensitivity to pain. Moreover, they suffer from severe sleep disturbances and have disrupted pattern in melatonin secretion. In healthy individuals, melatonin secretion from the pineal gland is strictly driven by the central clock in the hypothalamus. Therefore, melatonin levels are low during the day and high during the night. However, in SMS patients, melatonin levels could be high during the day and low during the night. We ascertained that this disruption does probably not originate directly in the pineal gland but rather arises due to disrupted timing cues, which are being send to the pineal gland from the central clock. This finding could be used in the future as the basis for the chronobiological treatment of some of the accompanying SMS symptoms.
While healthy children have melatonin secretion high during the night (A), melatonin secretion patterns in children with SMS are severely disrupted (B). (Nováková et al., J Clin Endocrinol Metab., 2012)