In search of the psychosis gene in people with Prader‐Willi syndrome

The two main causes of Prader‐Willi syndrome (PWS) are a paternally derived deletion in the maternally imprinted 15q11–q13 region or UPD(15)mat. Both mechanisms result in a loss of the active paternal contribution to the region. The affective psychosis associated with PWS has been found to be mainly confined to the propositi with UPD(15)mat rather than to those with a deletion. This suggests that the psychosis may be related to the presence of...