Articles

Background: approximately 15% of colorectal carcinomas (CRC) display high
microsatellite instability (MSI-H).
These originate when the DNA mismatchrepair system, known as the MMR system, is dysfunctional,
which results in the accumulation of mutations caused by DNA polymerase, like point mutations, deletions
and insertions.
Although they are heterogeneous, MSI-H colorectal carcinomas display different biological characteristics
when compared to stable or low MSI CRCs.
Purpose of the study: This study aims istoidentify molecular biomarkers that provide early prognostic
information.
Methods: in this research, the presence of MSI was determined using Bethesda panel, Multiplex Ligationdependent
Probe Amplification (MLPA) to detect Mismatch-repair (MMR) and BRAF mutation in patients
with colorectal cancer, and its importance was acknowledged for patients with suspected hereditary
nonpolyposis colorectal cancer (HNPCC) or with suspected Lynch syndrome.
Results: MSI-H was detected in 4 of the 31 cases (12.9%).Genomic rearrangements were not detected
(loss or gain of genetic material) in the genes MLH1, MSH2, MSH6, PMS2 and in the 3’ region of
EPCAM through MLPA in patients presenting MSI-H.The BRAF V600E mutation test was positive in all
four patients with MSI-H.
Conclusions: In this research, the molecular markers IMS, MSH6, MLH1, MSH2, PMS2 and BRAF
allowed us to set the behavior to be followed.
Therefore, we consider that the implementation of molecular tests is important to determine whether we
are facing cases of sporadic CRC or Lynch syndrome.