Hemizygous mutations in L1CAM in two unrelated male probands with childhood onset psychosis.

OBJECTIVE: To identify genes underlying childhood onset psychosis. METHODS: Patients with onset of psychosis at age 13 or younger were identified from clinics across England, and they and their parents were exome sequenced and analysed for possible highly penetrant genetic contributors. RESULTS: We report two male childhood onset psychosis patients of different ancestries carrying hemizygous very rare possibly damaging missense variants (p.Arg846His and p.Pro145Ser) in the L1CAM gene. L1CAM is an X-linked Mendelian disease gene in which both missense and loss of function variants are associated with syndromic forms of intellectual disability and developmental disorder. CONCLUSIONS: This is the first study reporting a possible extension of the phenotype of L1CAM variant carriers to childhood onset psychosis. The family history and presence of other significant rare genetic variants in the patients suggest that there may be genetic interactions modulating the presentation.