They observed a significant excess of variations in those with schizophrenia compared with those who had bipolar disorder both for total number of variations and for gene deletions specifically.

These deletions or duplications, also called copy-number changes, can change the dosage of a gene.

Tumor metastasis suppressor gene can inhibit the metastasis of tumor cells, mutations or deletions of this kind of genes can lead to tumor invasion and metastasis.