A rare large duplication of MLH1 identified in Lynch syndrome
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11140%2F21%3A10421672" target="_blank" >RIV/00216208:11140/21:10421672 - isvavai.cz</a>
Result on the web
<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=YrEeBdU~Pv" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=YrEeBdU~Pv</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1186/s13053-021-00167-0" target="_blank" >10.1186/s13053-021-00167-0</a>
Alternative languages
Result language
angličtina
Original language name
A rare large duplication of MLH1 identified in Lynch syndrome
Original language description
BACKGROUND: The most frequently identified strong cancer predisposition mutations for colorectal cancer (CRC) are those in the mismatch repair (MMR) genes in Lynch syndrome. Laboratory diagnostics include testing tumors for immunohistochemical staining (IHC) of the Lynch syndrome-associated DNA MMR proteins and/or for microsatellite instability (MSI) followed by sequencing or other techniques, such as denaturing high performance liquid chromatography (DHPLC), to identify the mutation. METHODS: In an ongoing project focusing on finding Mendelian cancer syndromes we applied whole-exome/whole-genome sequencing (WES/WGS) to 19 CRC families. RESULTS: Three families were identified with a pathogenic/likely pathogenic germline variant in a MMR gene that had previously tested negative in DHPLC gene variant screening. All families had a history of CRC in several family members across multiple generations. Tumor analysis showed loss of the MMR protein IHC staining corresponding to the mutated genes, as well as MSI. In family A, a structural variant, a duplication of exons 4 to 13, was identified in MLH1. The duplication was predicted to lead to a frameshift at amino acid 520 and a premature stop codon at amino acid 539. In family B, a 1 base pair deletion was found in MLH1, resulting in a frameshift and a stop codon at amino acid 491. In family C, we identified a splice site variant in MSH2, which was predicted to lead loss of a splice donor site. CONCLUSIONS: We identified altogether three pathogenic/likely pathogenic variants in the MMR genes in three of the 19 sequenced families. The MLH1 variants, a duplication of exons 4 to 13 and a frameshift variant, were novel, based on the InSiGHT and ClinVar databases; the MSH2 splice site variant was reported by a single submitter in ClinVar. As a variant class, duplications have rarely been reported in the MMR gene literature, particularly those covering several exons.
Czech name
—
Czech description
—
Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
—
OECD FORD branch
30204 - Oncology
Result continuities
Project
—
Continuities
R - Projekt Ramcoveho programu EK
Others
Publication year
2021
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Hereditary Cancer in Clinical Practice
ISSN
1731-2302
e-ISSN
—
Volume of the periodical
19
Issue of the periodical within the volume
1
Country of publishing house
PL - POLAND
Number of pages
7
Pages from-to
10
UT code for WoS article
000611935000002
EID of the result in the Scopus database
2-s2.0-85100178199