High homocysteine levels and mutations in the genes that regulate it have been found in bipolar, depressive and schizophrenic patients. Therefore, Permoda-Osip et al (2014) wished to understand the correlation between bipolar mood disorder and mutations in genes that encode MTHFR, CBS, MTR and MTRR enzymes. Bipolar patients were screened for the presence of these mutations and results compared with a control group. Overall, a gene mutation in the CBS pathway was found to be associated with bipolar, the first evidence of its kind to do.