SLC6A4 and Prader-Willi syndrome: PWS6 possessed a clinically relevant variant in the autosomal dominant SLC6A4 gene shown to be associated with anxiety‐related personality trait and obsessive‐compulsive disorder (Ozaki et al., 2003; Zhang, Gesmonde, Ramamoorthy, & Rudnick, 2007), common findings in PWS.