The influence of genetic background on tumour phenotype may therefore explain the differences observed in four previously reported Men1+/- conventional mouse models; for example, gastric neuroendocrine tumours were reported only in a mixed NIH Black Swiss and 129/SvEvTacFBR model (Supplementary Table 4) (19, 29, 30, 31). The gene discussed is MEN1; the disease is gastric neuroendocrine tumor, well differentiated, low or intermediate grade.