Initial results of colorectal polyposis research in Latvia

Patients suffering from colorectal polyps are more likely to develop a malignant condition with poor prognosis. The aim of the study is to investigate clinical and molecular features of colorectal polyposis syndromes in Latvia in order to offer and provide predictive genetic testing for the affected families, as well as to evaluate the frequency of familial adenomatous polyposis (FAP) in Latvia.

Six polyposis patients along with three of their relatives were included in this study. Two patients were selected from the colorectal cancer database (from a total of 2,552), and four patients not affected with colorectal cancer (CRC) were referred from the endoscopic facility of our hospital. All the patients were examined during the period from January 1st, 2000 until June 30th, 2007. Clinical data, histological examinations and family cancer histories of the respective patients were evaluated. Screening for germline APC mutations was performed in five patients and their relatives. In addition, all patients underwent genetic counseling.

Two patients out of 2,552 from the CRC Hereditary Cancer Institute database fulfilled the clinical criteria for FAP. Thus, the frequency of FAP is 0.08% (2/2,552) of all CRC cases, and comprises approximately 0.0003% of the population of Latvia (7/22 million inhabitants). Unknown polyposis was identified in two cases. Pathogenic APC gene mutations were detected in five out of seven examined patients and their relatives. Two of the mutations (c.3942delG:p.Arg1314SerfsX7 and c.3286C > T;p.Gln1096X) are novel.

In this study, we report the first four APC mutation-positive FAP cases in Latvia. The present frequency of FAP is lower than that reported in Finland, Lithuania, and other neighbouring countries, but the numbers might increase if a more systematic identification approach is used. Initial molecular examinations reveal partially unique spectrum of APC gene mutations.