chr12-25227351-G-A

Variant names:

• chr12-25227351-G-A
• rs104894364
• NM_004985.5:c.173C>T

Variant summary

Our verdict is Pathogenic. The variant received 14 ACMG points: 14P and 0B. PP2 PP3 PM2 PM1 PS3 PM6_Strong

This summary comes from the ClinGen Evidence Repository: The c.173C>T (p.Thr58Ile) variant in KRAS has been reported in the literature as an unconfirmed de novo occurrence in a patient with clinical features of a RASopathy (PM6_Strong; PMID 23321623, 20112233, 16921267, 16474405, 22488832, 18247425, 20949621). This variant was absent from large population studies (PM2; ExAC, http://exac.broadinstitute.org). In vitro functional studies provide some evidence that the p.Thr58Ile variant may impact protein function (PS3; PMID:23321623, 20949621, 16921267). Furthermore, the variant is in a location that has been defined by the ClinGen RASopathy Expert Panel to be a mutational hotspot or domain of KRAS (PM1; PMID 29493581). The variant is located in the KRAS gene, which has been defined by the ClinGen RASopathy Expert Panel as a gene with a low rate of benign missense variants and pathogenic missense variants are common (PP2; PMID:29493581). Computational prediction tools and conservation analysis suggest that the p.Thr58Ile variant may impact the protein (PP3). In summary, this variant meets criteria to be classified as pathogenic for RASopathies in an autosomal dominant manner. Rasopathy-specific ACMG/AMP criteria applied (PMID:29493581): PM6_Strong, PS3, PM2, PM1, PP2, PP3. LINK:https://erepo.genome.network/evrepo/ui/classification/CA256480/MONDO:0018997/004

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: KRAS NM_004985.5 missense
• Clinical Significance: Pathogenic reviewed by expert panel P:7
• Conservation: PhyloP100: 9.98
• Publications: 95 publications found

Genes affected

KRAS (HGNC:6407): (KRAS proto-oncogene, GTPase) This gene, a Kirsten ras oncogene homolog from the mammalian ras gene family, encodes a protein that is a member of the small GTPase superfamily. A single amino acid substitution is responsible for an activating mutation. The transforming protein that results is implicated in various malignancies, including lung adenocarcinoma, mucinous adenoma, ductal carcinoma of the pancreas and colorectal carcinoma. Alternative splicing leads to variants encoding two isoforms that differ in the C-terminal region. [provided by RefSeq, Jul 2008]

KRAS Gene-Disease associations (from GenCC):

• cardiofaciocutaneous syndrome 2

  Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE Submitted by: Labcorp Genetics (formerly Invitae), G2P, Genomics England PanelApp, Ambry Genetics, PanelApp Australia
• Noonan syndrome

  Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: ClinGen, Orphanet
• Noonan syndrome 3

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, PanelApp Australia, Ambry Genetics, Labcorp Genetics (formerly Invitae), Genomics England PanelApp
• cardiofaciocutaneous syndrome

  Inheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, ClinGen
• linear nevus sebaceous syndrome

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• Costello syndrome

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Pathogenic. The variant received 14 ACMG points.

• PS3: For more information check the summary or visit ClinGen Evidence Repository.
• PM1: For more information check the summary or visit ClinGen Evidence Repository.
• PM2: For more information check the summary or visit ClinGen Evidence Repository.
• PM6: For more information check the summary or visit ClinGen Evidence Repository.
• PP2: For more information check the summary or visit ClinGen Evidence Repository.
• PP3: For more information check the summary or visit ClinGen Evidence Repository.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KRAS	NM_004985.5	c.173C>T	p.Thr58Ile	missense_variant	Exon 3 of 5	ENST00000311936.8	NP_004976.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KRAS	ENST00000311936.8	c.173C>T	p.Thr58Ile	missense_variant	Exon 3 of 5	1	NM_004985.5	ENSP00000308495.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461754 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727188

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39684

South Asian (SAS) AF: 0.00 AC: 0 AN: 86252

European-Finnish (FIN) AF: 0.0000187 AC: 1 AN: 53412

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111910

Other (OTH) AF: 0.00 AC: 0 AN: 60394

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:7

Revision: reviewed by expert panel

Submissions by phenotype

Noonan syndrome 3 Pathogenic:3

May 01, 2009

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Feb 28, 2020

Beijing Key Laboratry for Genetics of Birth Defects, Beijing Children's Hospital

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Apr 14, 2022

Institute of Human Genetics, University Hospital Muenster

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

ACMG categories: PS3,PM1,PM2,PM6,PP3,PP5 -

Noonan syndrome Pathogenic:2

Apr 03, 2017

ClinGen RASopathy Variant Curation Expert Panel

Significance: Pathogenic

Review Status: reviewed by expert panel

Collection Method: curation

The c.173C>T (p.Thr58Ile) variant in KRAS has been reported in the literature as an unconfirmed de novo occurrence in a patient with clinical features of a RASopathy (PM6_Strong; PMID 23321623, 20112233, 16921267, 16474405, 22488832, 18247425, 20949621). This variant was absent from large population studies (PM2; ExAC, http://exac.broadinstitute.org). In vitro functional studies provide some evidence that the p.Thr58Ile variant may impact protein function (PS3; PMID: 23321623, 20949621, 16921267). Furthermore, the variant is in a location that has been defined by the ClinGen RASopathy Expert Panel to be a mutational hotspot or domain of KRAS (PM1; PMID 29493581). The variant is located in the KRAS gene, which has been defined by the ClinGen RASopathy Expert Panel as a gene with a low rate of benign missense variants and pathogenic missense variants are common (PP2; PMID: 29493581). Computational prediction tools and conservation analysis suggest that the p.Thr58Ile variant may impact the protein (PP3). In summary, this variant meets criteria to be classified as pathogenic for RASopathies in an autosomal dominant manner. Rasopathy-specific ACMG/AMP criteria applied (PMID:29493581): PM6_Strong, PS3, PM2, PM1, PP2, PP3. -

Mar 25, 2014

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The Thr58Ile variant in KRAS has been previously reported in at least one fetus, one infant, and one child with clinical features of Noonan syndrome (Schubbert 2006, Houweling 2010, Croonen 2013, LMM-unpublished data). In both the fetus and the infant, the variant was reported to be de novo (Schubbert 2006, Croonen 201 3). Functional studies show that this variant impacts the protein's GTPase activ ity and leads to overall enhanced downstream signaling (Schubbert 2006, Gremer 2 010). In addition, this variant was absent from large population studies. In sum mary, this variant meets our criteria to be classified as pathogenic (http://pcp gm.partners.org/LMM). -

not provided Pathogenic:1

Apr 12, 2024

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Identified in patients with Noonan syndrome and Noonan-like features referred for genetic testing at GeneDx and in published literature, including as a de novo variant without confirmed parentage (PMID: 16474405, 23321623); Published functional studies demonstrate a damaging effect caused by defective GTP hydrolysis and hypersensitive responsiveness to GTPase activating proteins resulting in an overall enhancement in RAS signaling (PMID: 16474405, 20949621); Missense variants in this gene are often considered pathogenic (HGMD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 19396835, 16921267, 20949621, 23321623, 30055033, 26918529, 32021610, 34539730, 33726816, 35418823, 34643321, 16474405, 17875937, 29493581) -

RASopathy Pathogenic:1

Sep 04, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces threonine, which is neutral and polar, with isoleucine, which is neutral and non-polar, at codon 58 of the KRAS protein (p.Thr58Ile). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with Noonan syndrome and Costello syndrome and Noonan syndrome (PMID: 16474405, 17704260, 19396835, 20186801). In at least one individual the variant was observed to be de novo. ClinVar contains an entry for this variant (Variation ID: 12588). Invitae Evidence Modeling incorporating data from in vitro experimental studies (internal data) indicates that this missense variant is expected to disrupt KRAS function with a positive predictive value of 95%. Experimental studies have shown that this missense change affects KRAS function (PMID: 16474405, 20949621). For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.46	D
BayesDel_noAF	Pathogenic	0.42
CADD	Pathogenic	32
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.89	.;D
Eigen	Pathogenic	0.99
Eigen_PC	Pathogenic	0.90
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.93	D;D
M_CAP	Uncertain	0.26	D
MetaRNN	Pathogenic	0.95	D;D
MetaSVM	Pathogenic	0.96	D
MutationAssessor	Uncertain	2.8	M;M
PhyloP100		10
PrimateAI	Pathogenic	0.93	D
PROVEAN	Pathogenic	-5.6	D;D
REVEL	Pathogenic	0.92
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0	D;D
Polyphen		1.0	D;D
Vest4		0.98
MutPred		0.83		Gain of catalytic residue at A59 (P = 0);Gain of catalytic residue at A59 (P = 0);
MVP		0.99
MPC		2.8
ClinPred		1.0	D
GERP RS		4.9
Varity_R		0.99
gMVP		0.97
Mutation Taster		=13/87	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs104894364; hg19: chr12-25380285; COSMIC: COSV55527371; COSMIC: COSV55527371;