However, our study cannot answer the question whether the association between the identified SNPs and hippocampal volume is specific to schizophrenia but it has been suggested that a variety of other polymorphisms with small effect sizes, reciprocal effects with risk alleles of other genes, copy number variants and environmental influences may constitute a background of risk factors that could interact with the effects of NR2F6, USHBP1 and BABAM1 to increase schizophrenia susceptibility. This evidence concerns the gene USHBP1 and schizophrenia.