Our verdict is Likely benign. Variant got -1 ACMG points: 0P and 1B. BP6
The NM_000249.4(MLH1):c.589-9_589-6delGTTT variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000081 in 1,604,118 control chromosomes in the GnomAD database, with no homozygous occurrence. 1/1 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).
MLH1 (HGNC:7127): (mutL homolog 1) The protein encoded by this gene can heterodimerize with mismatch repair endonuclease PMS2 to form MutL alpha, part of the DNA mismatch repair system. When MutL alpha is bound by MutS beta and some accessory proteins, the PMS2 subunit of MutL alpha introduces a single-strand break near DNA mismatches, providing an entry point for exonuclease degradation. The encoded protein is also involved in DNA damage signaling and can heterodimerize with DNA mismatch repair protein MLH3 to form MutL gamma, which is involved in meiosis. This gene was identified as a locus frequently mutated in hereditary nonpolyposis colon cancer (HNPCC). [provided by RefSeq, Aug 2017]
Verdict is Likely_benign. Variant got -1 ACMG points.
BP6
Variant 3-37011996-CTGTT-C is Benign according to our data. Variant chr3-37011996-CTGTT-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 234371.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=3, Uncertain_significance=6}. Variant chr3-37011996-CTGTT-C is described in Lovd as [Likely_benign].
Uncertain significance, criteria provided, single submitter
clinical testing
Ambry Genetics
Aug 17, 2022
The c.589-9_589-6delGTTT alteration is located in Intron 7 (E) of the MLH1 gene. This alteration consists of a deletion of 4 nucleotides at nucleotide position c.589-9 Intron 7 (E). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -
Likely benign, criteria provided, single submitter
clinical testing
Color Diagnostics, LLC DBA Color Health
Nov 20, 2023
- -
Uncertain significance, criteria provided, single submitter
curation
Sema4, Sema4
Dec 19, 2021
- -
not provided Uncertain:1Benign:1
Likely benign, criteria provided, single submitter
clinical testing
GeneDx
Aug 25, 2020
This variant is associated with the following publications: (PMID: 15991306) -
Uncertain significance, criteria provided, single submitter
clinical testing
Quest Diagnostics Nichols Institute San Juan Capistrano
May 10, 2023
The frequency of this variant in the general population, 0.00022 (11/50742 chromosomes, http://gnomad.broadinstitute.org), is uninformative in assessment of its pathogenicity. In the published literature, the variant has been reported in individuals affected with a Lynch syndrome associated cancer and/or precancerous lesion, and co-segregation with disease was noted in a limited number of families (PMIDs: 15991306 (2005), 31068090 (2019), 34039291 (2021), 35475445 (2022), 36983044 (2023)). Experimental studies have shown that this variant causes exon skipping (PMIDs: 15991306 (2005), 36983044 (2023)), however, further research is needed. Based on the available information, we are unable to determine the clinical significance of this variant. -
not specified Uncertain:1
Uncertain significance, criteria provided, single submitter
clinical testing
Women's Health and Genetics/Laboratory Corporation of America, LabCorp
Mar 13, 2023
Variant summary: MLH1 c.589-9_589-6delGTTT removes 4 nucleotides located close to a canonical splice site and therefore could affect mRNA splicing, leading to a significantly altered protein sequence. Three computational tools predict no significant impact on normal splicing, while one tool predicts that the variant abolishes a the 3' acceptor site. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 7.6e-05 in 251328 control chromosomes (gnomAD). This frequency is not higher than the estimated maximum expected for a pathogenic variant in MLH1 causing Hereditary Nonpolyposis Colorectal Cancer (0.00071), allowing no conclusion about variant significance. The variant, c.589-9_589-6delGTTT, has been reported in the literature in individuals affected with (suspected) Hereditary Nonpolyposis Colorectal Cancer (e.g. Otway_2005, Ricci_2019, Talbot_2021, Liccardo_2022). These data do not allow clear conclusions about variant significance. Co-occurrences with other pathogenic variant(s) have been reported (MSH2 c.484G>A, p.Gly162Arg; in an internal LCA sample), providing supporting evidence for a benign role. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Five other submitters have provided clinical-significance assessments for this variant in ClinVar after 2014, mostly without evidence for independent evaluation, and classified the variant as VUS (n=3) or likely benign (n=2). Based on the evidence outlined above, the variant was classified as uncertain significance. -
Breast and/or ovarian cancer Uncertain:1
Uncertain significance, criteria provided, single submitter
clinical testing
CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario
Oct 13, 2022
- -
Hereditary breast ovarian cancer syndrome Uncertain:1
Uncertain significance, criteria provided, single submitter
curation
German Consortium for Hereditary Breast and Ovarian Cancer, University Hospital Cologne
Sep 10, 2024
According to the ClinGen InSiGHT ACMG MLH1 v1.0.0 criteria we chose this criterion: PS3 (pathogenic Strong:): mRNA analysis, skipping of exon 8 (c. 589_677), Nolano (2023) Int J Mol Sci 24: PubMed: 36983044; Thompson BA, Walters R, Parsons MT, Dumenil T, Drost M, Tiersma Y, Lindor NM, Tavtigian SV, de Wind N, Spurdle AB; InSiGHT Variant Interpretation Committee. Contribution of mRNA Splicing to Mismatch Repair Gene Sequence Variant Interpretation. Front Genet. 2020 Jul 27;11:798. doi: 10.3389/fgene.2020.00798. PMID: 32849802; PMCID: PMC7398121 --> Supplementary Table 3; Strength? -