Unique MLH1 mutations in colonic adenomas in an obligate germline Lynch syndrome carrier.
J Clin Pathol
; 73(5): 291-295, 2020 May.
Article
in En
| MEDLINE
| ID: mdl-31649038
ABSTRACT
BACKGROUND:
An obligate germline Lynch syndrome carrier had four colonic adenomas removed. MATERIALS ANDMETHODS:
The adenomas were evaluated for grade of dysplasia, MLH1, PMS2, MSH2 and MSH6 protein expression, microsatellite instability (MSI), BRAF, methylation status and a next-generation sequencing (NGS) panel of 52 cancer genes.RESULTS:
There were four tubular or tubulovillous adenomas from the hepatic flexure, rectosigmoid and rectum; one with low-grade and high-grade dysplasia, one with high-grade dysplasia only and two with low-grade dysplasia. All four adenomas showed retention of MLH1, MHS2 and MSH6 but complete loss of PMS2 in both low-grade and high-grade dysplasia areas.Two of the four adenomas were MSI-high, BRAF V600E wild type and were not MLH1 methylated. NGS identified an MLH1 germline variant NM_000249.3 c.1558+1 G>A, p.(?) in all tissue (adenomas and normal), which likely explains the pathophysiology of Lynch syndrome in this patient. Other variants were also detected in MLH1 and MSH6 in all four adenomas tested; these being reported previously in somatic colorectal cancers.CONCLUSION:
We highlight an MLH1 variant in the colonic adenomas in an obligate Lynch syndrome carrier that resulted in PMS2 protein loss in the absence of mutations of the PMS2 gene.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Colorectal Neoplasms, Hereditary Nonpolyposis
/
Biomarkers, Tumor
/
Adenoma
/
Germ-Line Mutation
/
MutL Protein Homolog 1
Type of study:
Prognostic_studies
Limits:
Adult
/
Humans
/
Male
Language:
En
Journal:
J Clin Pathol
Year:
2020
Document type:
Article
Affiliation country:
Canada