This further ties in with a study by Webb et al. [72], which showed that in a significant proportion of the PWS-del individuals that exhibit psychosis, carry a larger deletion that spans part of GABRG3. This suggests that the GABA receptor could also be contributing to psychotic illness in individuals with the mUPD15 genotype due to reduced functionality caused by differential isoform usage. This evidence concerns the gene GABRG3 and psychotic disorder.