The levels of expression of these genes in the healthy family members of the patients demonstrated only a slight difference in MDMX and MDM2 mRNA levels when comparing family members and controls; in the case of p53 mRNA, the differences are significant between patients family member and healthy, unrelated controls, suggesting a hereditary factor is associated with the p53 pathway during development of the tumour in these patients. This evidence concerns the gene MDM4 and neoplasm.