Although MDM2 amplification and TP53 mutations have been shown to indicate HPD by some researchers, other studies have shown that advanced gastric tumour patients without HPD also exhibit genetic changes, such as ERBB2 amplification, MDM2 amplification, TP53 mutations, KRAS amplification, and PIK3CA mutations, indicating that these changes may not be HPD-specific (182). The gene discussed is MDM2; the disease is gastric neoplasm.