PIGO and neoplasm: While the allele depth of MSH6, PIGO and AXIN2 mutant alleles ranged from 20–39% in the tumour, the allele depth of the MLH1 mutant in the tumour (73%) was found to be nearly double compared to that in the blood (germline variant, 38%), suggesting a possible second hit in the MLH1 gene in the tumour cells.