NM_000179.3:c.3801+5G>A
Variant summary
Our verdict is Uncertain significance. Variant got 0 ACMG points: 1P and 1B. PP3BP6
The NM_000179.3(MSH6):c.3801+5G>A variant causes a splice region, intron change. The variant allele was found at a frequency of 0.0000508 in 1,614,104 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).
Frequency
Consequence
NM_000179.3 splice_region, intron
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Uncertain_significance. Variant got 0 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.0000526 AC: 8AN: 152164Hom.: 0 Cov.: 33
GnomAD3 exomes AF: 0.0000876 AC: 22AN: 251178Hom.: 0 AF XY: 0.0000663 AC XY: 9AN XY: 135770
GnomAD4 exome AF: 0.0000506 AC: 74AN: 1461822Hom.: 0 Cov.: 33 AF XY: 0.0000550 AC XY: 40AN XY: 727204
GnomAD4 genome AF: 0.0000525 AC: 8AN: 152282Hom.: 0 Cov.: 33 AF XY: 0.0000134 AC XY: 1AN XY: 74452
ClinVar
Submissions by phenotype
Lynch syndrome 5 Uncertain:2Benign:1
This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -
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This variant is considered likely benign. This variant is strongly associated with less severe personal and family histories of cancer, typical for individuals without pathogenic variants in this gene [PMID: 25085752]. -
not provided Uncertain:1Benign:2
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The MSH6 c.3801+5G>A variant was identified in 3 of 4640 proband chromosomes (frequency: 0.0006) from individuals or families with breast, ovarian or colon cancer (Shirts 2016, Yorczyk 2014, Tung 2016). The variant was also identified in the following databases: dbSNP (ID: rs201080919) as “With other allele” and ClinVar (2x as likely benign by Ambry Genetics and University of Washington, 5x as uncertain significance by Invitae, GeneDx, Counsyl, Integrated Genetics, Illumina Clinical services) The variant was not identified in COGR, Cosmic, MutDB, UMD-LSDB, Zhejiang Colon Cancer Database, or Insight Hereditary Tumors Database. The variant was identified in control databases in 22 of 245988 chromosomes at a frequency of 0.00009 increasing the likelihood this could be a low frequency variant (Genome Aggregation Database Feb 27, 2017). The variant was observed in the following populations: Other in 1 of 5476 chromosomes (freq: 0.0002), Latino in 7 of 33544 chromosomes (freq: 0.0002), European Non-Finnish in 9 of 111508 chromosomes (freq: 0.00008), Ashkenazi Jewish in 5 of 9848 chromosomes (freq: 0.0005), while the variant was not observed in the African, East Asian, European Finnish, or South Asian populations. The c.3801+5G>A variant is located in the 5' splice region but does not affect the invariant +1 and +2 positions. However, positions +3 to +6 are part of the splicing consensus sequence and variants involving these positions sometimes affect splicing. In addition, 4 of 4 in silico or computational prediction software programs (SpliceSiteFinder, MaxEntScan, NNSPLICE, GeneSplicer) predict a greater than 10% difference in splicing. In summary, based on the above information the clinical significance of this variant cannot be determined with certainty at this time. This variant is classified as a variant of uncertain significance. -
In silico analysis, which includes splice predictors and evolutionary conservation, is inconclusive as to whether the variant alters gene splicing. In the absence of RNA/functional studies, the actual effect of this sequence change is unknown.; Observed in individuals with colorectal and breast cancers (Shirts 2016, Tung 2016, Yurgelun 2017); This variant is associated with the following publications: (PMID: 28135145, 31642931, 25318351, 26976419, 26845104) -
Hereditary cancer-predisposing syndrome Uncertain:1Benign:2
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This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -
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Lynch syndrome Benign:2
Communication from other laboratories about other patients with this variant and no family history of colorectal cancer. Splicing anlaysis indicates 95% full length product. -
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not specified Benign:1
Variant summary: MSH6 c.3801+5G>A alters a conserved nucleotide located close to a canonical splice site and therefore could affect mRNA splicing, leading to a significantly altered protein sequence. Several computational tools predict a significant impact on normal splicing: One predict the variant weakens the canonical 5' splicing donor site. Three predict the variant abolishes the canonical 5' splicing donor site. However, RNA studies demonstrate this variant has no abnormal splicing (Karam_2019). The variant allele was found at a frequency of 8.8e-05 in 251178 control chromosomes. This frequency is not significantly higher than estimated for a pathogenic variant in MSH6 causing Hereditary Nonpolyposis Colorectal Cancer/Lynch syndrome (8.8e-05 vs 0.00014), allowing no conclusion about variant significance. c.3801+5G>A has been reported in the literature in individuals affected with breast cancer, colorectal cancer, Lynch Syndrome as well as in healthy individuals and also as a VUS in settings of multigene panel testing (example, Shirts_2016, Tung_2016, Yorczyk_2015, Yurgelun_2017, Karam_2019, de Oliveira_2022). These report(s) do not provide unequivocal conclusions about association of the variant with Hereditary Nonpolyposis Colorectal Cancer/Lynch syndrome. At-least two co-occurrences with other pathogenic variant(s) have been observed at our laboratory (RB1 c.1399C>T, p.Arg467X; BRCA1 c.2411_2412delAG, p.Gln804LeufsX5), providing supporting evidence for a benign role. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 34445333, 31642931, 26845104, 26976419, 25318351, 28135145, 35534704). ClinVar contains an entry for this variant (Variation ID: 186876). Based on the evidence outlined above, the variant was classified as likely benign. -
Hereditary nonpolyposis colorectal neoplasms Benign:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at