Challenges and pitfalls in HNPCC: a pedigree of an Austrian HNPCC family beyond four generations

Summary In this study we present an Austrian family with HNPCC, which was diagnosed by clinical criteria (Amsterdam I). Subsequent to the diagnosis, genetic counselling and testing was offered to all family members. A causal mutation was detected in exon 12 of the MLH1 gene by determining the genomic sequence. The mutation had resulted in the deletion of an adenine nucleotide at position 1343 (c.1343delA; respective cDNA NCBI accession number: NM_000249), creating a new reading frame (p.E448fs). Within this pedigree it was possible, with frequent colonoscopy screening, to detect an early-stage tumour localised in the coecum. Furthermore, there is evidence for genetic anticipation. The median ages at diagnosis of colorectal cancer decreased from 51.5 in the second generation to 33.5 in the third generation.