HCRT and Prader-Willi syndrome: In genome wide expression studies, Bittel et al. [62] reported elevated expression patterns of the hypocretin (HCRT) gene in males with PWS, although an early study by Fronczek et al. [63] did not show a significant difference in the total number of hypocretin-containing neurons among PWS patients and age-matched controls, either in adults or infants.