Generally, blood and saliva sample are used for the germ-line TP53 genetic testing. However, clinical research found that aberrant clonal expansion is an interference for germ-line test result, and the interference leads to an increased false positive rate. False interpretation can result in unnecessary medical management of patients and psychological stress for family members. Hence, the test result with more than two mutations or abnormal sequencing allele frequency should be confirmed with the DNA from another source, e.g. skin biopsy or eyebrow plucks. Moreover, the higher the ratio of detected mutation in the blood, the higher the chance of the patient developing hematological malignancy.