Submissions for variant NM_000249.3(MLH1):c.2101C>A (p.Gln701Lys) (rs63750114)

Total submissions: 14

Submitter	RCV	SCV	Clinical significance	Condition	Last evaluated	Review status	Method	Comment
International Society for Gastrointestinal Hereditary Tumours (InSiGHT)	RCV000075527	SCV000106524	likely benign	Lynch syndrome	2013-09-05	reviewed by expert panel	research	Co-occurrence without CMMRD phenotype & MAF 0.01-1%. Multifactorial likelihood analysis posterior probability 0.001-0.049
Ambry Genetics	RCV000130401	SCV000185261	benign	Hereditary cancer-predisposing syndrome	2014-11-18	criteria provided, single submitter	clinical testing	General population or subpopulation frequency is too high to be a pathogenic mutation based on disease/syndrome prevalence and penetrance;In silico models in agreement (benign);Seen in trans with a mutation or in homozygous state in individual without severe disease for that gene
GeneDx	RCV000587809	SCV000211150	likely benign	not provided	2020-05-18	criteria provided, single submitter	clinical testing	This variant is associated with the following publications: (PMID: 16929514, 30521064, 23760103, 17011982, 18931482, 18726168, 18383312, 24933000, 22136435, 22995991, 18094436, 26811195, 23431106, 26900293, 26078562, 24710284, 23047549, 26332594, 29192238, 29050249, 25338684, 25479140, 29360550, 30093976, 31784484)
Genomic Diagnostic Laboratory, Division of Genomic Diagnostics,Children's Hospital of Philadelphia	RCV000075527	SCV000257651	uncertain significance	Lynch syndrome	2015-05-14	criteria provided, single submitter	clinical testing
Soonchunhyang University Bucheon Hospital,Soonchunhyang University Medical Center	RCV000490357	SCV000267396	uncertain significance	Lynch syndrome II	2016-03-18	criteria provided, single submitter	reference population
Invitae	RCV001086186	SCV000284046	benign	Hereditary nonpolyposis colorectal neoplasms	2020-12-04	criteria provided, single submitter	clinical testing
Color Health, Inc	RCV000130401	SCV000537451	likely benign	Hereditary cancer-predisposing syndrome	2015-04-27	criteria provided, single submitter	clinical testing
Women's Health and Genetics/Laboratory Corporation of America, LabCorp	RCV000254664	SCV000696145	benign	not specified	2019-04-29	criteria provided, single submitter	clinical testing	Variant summary: MLH1 c.2101C>A (p.Gln701Lys) results in a conservative amino acid change located in the DNA mismatch repair protein Mlh1, C-terminal domain of the encoded protein sequence that is necessary for interaction with PSM2 (Fan_2007). Three of five in-silico tools predict a benign effect of the variant on protein function. 5/5 computational tools predict no significant impact on normal splicing. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 0.0005 in 251174 control chromosomes (gnomAD and publication data), predominantly at a frequency of 0.0066 within the East Asian subpopulation in the gnomAD database. The observed variant frequency within East Asian control individuals in the gnomAD database is approximately 9 fold of the estimated maximal expected allele frequency for a pathogenic variant in MLH1 causing Lynch Syndrome phenotype (0.00071), strongly suggesting that the variant is a benign polymorphism found primarily in populations of East Asian origin. This variant has been reported in multiple sequencing studies among individuals of East Asian ancestry with a variety of cancers to include, Lynch Syndrome, biliary tract cancer and colon cancer (Zhi_2011, Talseth-Palmer_2016, Chan_2018, Kim_2017, Wardell_2018). Thus, these reports do not provide unequivocal conclusions about association of the variant with Lynch Syndrome. In addition, at-least one co-occurrence with the other potentially pathogenic variant (MLH1 c.208-1G>A) has been reported, providing supporting evidence for a benign role (Sheng_2008). A functional study demonstrated the variant to retain about 70% of its ability to interact with PMS2 (Fan_2007). Six clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation (VUS (n=2), likely benign (n=2), and benign (n=2)). One expert panel (InSiGHT) has submitted clinical-significance assessment for this variant to ClinVar before 2014 and classified the variant as likely benign. As all of the evidence outlined above, spanning over a decade supports a non-pathogenic outcome, the variant was classified as benign.
Quest Diagnostics Nichols Institute San Juan Capistrano	RCV000587809	SCV000889398	benign	not provided	2017-10-20	criteria provided, single submitter	clinical testing
Mendelics	RCV000490357	SCV001136435	benign	Lynch syndrome II	2019-05-28	criteria provided, single submitter	clinical testing
Illumina Clinical Services Laboratory,Illumina	RCV000490357	SCV001307915	uncertain significance	Lynch syndrome II	2017-04-28	criteria provided, single submitter	clinical testing	This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). Publications were found based on this search. However, the evidence from the literature, in combination with allele frequency data from public databases where available, was not sufficient to rule this variant in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance.
CeGaT Praxis fuer Humangenetik Tuebingen	RCV000587809	SCV001748067	uncertain significance	not provided	2021-02-01	criteria provided, single submitter	clinical testing
Ding PR Lab,Sun Yat-sen University Cancer Center	RCV001093671	SCV001250852	uncertain significance	Lynch syndrome I		no assertion criteria provided	clinical testing
Department of Pathology and Laboratory Medicine,Sinai Health System	RCV000587809	SCV001551649	likely benign	not provided		no assertion criteria provided	clinical testing	The MLH1 p.Gln701Lys variant was identified in 17 of 1894 proband chromosomes (frequency: 0.009) from individuals or families with Lynch syndrome or gastric cancer and was present in 3 of 1818 control chromosomes (frequency: 0.002) from healthy individuals (Chen 2013, Fan 2007, Sheng 2008, Talseth-Palmer 2016, Yap 2009, Zhang 2006, Zhi 2011). The variant was also identified in the following databases: dbSNP (ID: rs63750114) as "With Pathogenic, other allele", ClinVar (3x likely benign including InSiGHT expert panel, 2x benign, 2x uncertain significance), Clinvitae (4x), Cosmic (1x, confirmed somatic, in adenocarcinoma of large intestine), Insight Colon Cancer Gene Variant Database (10x, Likely not pathogenic/little clinical significance), Zhejiang Colon Cancer Database (4x), Mismatch Repair Genes Variant Database, and the Insight Hereditary Tumors Database (11x). The variant was not identified in MutDB or the UMD-LSDB database. The variant was identified in control databases in 129 of 276412 chromosomes at a frequency of 0.0005 increasing the likelihood this could be a low frequency benign variant (Genome Aggregation Database Feb 27, 2017). It was observed in the following populations: African in 1 of 23994 chromosomes (freq: 0.00004), Other in 2 of 6450 chromosomes (freq: 0.0003), and East Asian in 126 of 18826 chromosomes (freq: 0.007). The variant was not observed in the Latino, European, Ashkenazi Jewish, Finnish, or South Asian populations. A functional study utilizing a yeast two-hybrid assay showed that MLH1 p.Gln701Lys interacts with PMS2 at reduced efficiency (16.6% relative activity in comparison with wild-type MLH1) (Fan 2007). In the same study, a co-immunoprecipitation assay demonstrated p.Gln701Lys retains 70% interaction with PMS2 (Fan 2007). Thus, the functional studies do not show consistent results. A study by Zhi 2011 found that the c.2101C>A genotype was associated with an increased risk of gastric cancer (OR = 8.42, 95% CI = 1.04-68.06) in Chinese males. The p.Gln701 residue is conserved in mammals but not in more distantly related organisms, and four out of five computational analyses (PolyPhen-2, SIFT, AlignGVGD, BLOSUM, MutationTaster) do not suggest a high likelihood of impact to the protein; this information is not predictive enough to rule out pathogenicity. The p.Gln701Lys variant occurs in the 3rd last base of the exon. This position has been shown to be part of the splicing consensus sequence and variants involving this position sometimes affect splicing. However, in silico or computational prediction software programs (SpliceSiteFinder, MaxEntScan, NNSPLICE, GeneSplicer, HumanSpliceFinder) do not predict a difference in splicing. In summary, based on the above information the clinical significance of this variant cannot be determined with certainty at this time although we would lean towards a more benign role for this variant. This variant is classified as likely benign.