Evaluation of adenomatous polyposis coli gene negative polyposis coli patients in terms of myosin heavy chain mutations using molecular genetic methods

Familial adenomatous polyposis (FAP) is a disease that is rare and genetic transition. Mutations in adenomatous polyposis coli (APC), mutY Homolog (MUTYH/MYH) and DNA Polymerase delta 1 (POLD1) and Polymerase epsilon (POLE) genes are held responsible for the development of FAP. In our study, the presence of MUTYH / MYH gene mutation or polymorphism was investigated in patients with polyposis who had a family history of polyposis coli or colorectal cancer (CRC) and whose APC gene mutation was found negative. According to the colonoscopy findings of the Fırat University Faculty of Medicine Gastroenterology Endoscopy Unit between September 2017 and June 2018, there were 30 patients who met the inclusion criteria were evaluated. The MYH gene in DNA samples isolated from the blood taken from the participants was sequenced by the dideoxynucleotide (Sanger) method and examined for genetic variations. A total of 30 patients, 21 male and 9 female, with an average age of 46.8 ± 12.7 years, were included in the study. The mean age at diagnosis was 43.8 ± 13.1 years. Single Nucleotide Variant (SNV) positivity was observed in any exon region of 28 patients by genetic analysis. SNV positivity was found in exon 4-5 in 22 patients (73.3%), exon 6-7 in 20 patients (66.7%), and exon 10 in 18 patients (60%). Exon 6-7 positivity in women was statistically significantly higher than men (p = 0.013). The mean age of CRC in the family was significantly lower in those with exon 10 positivity (p = 0.026). As a result, SNV positivity was observed in at least one exon region in a great majority of the group whose APC gene sequence analysis was negative. MYH mutation was detected in all patients with cancer. The sequencing of the MHY gene with molecular analysis will be useful for the intelligibility of genetic transmission in FAP patients. Key Words: Colorectal cancer, Polyposis coli, APC, MYH, Gene analysis