Genetic Information

Gene & Transcript Details

Gene
KRAS
Transcript
NM_033360.4 MANE Select
Total Exons
Reference Sequence
NC_000012.11
Alternative Transcripts
IDStatusDetails
NM_033360.2 Alternative 5436 nt | 182–751
NM_033360.4 Alternative 5430 nt | 191–760
NM_033360.3 Alternative 5889 nt | 193–762

Variant Details

HGVS Notation
NM_033360.4:c.204G>C
Protein Change
R68S
Location
Exon 3 (Exon 3 of )
3
5'Exon Structure3'
Functional Consequence
Loss of Function
Alternate Identifiers

Clinical & Population Data

Population Frequency

gnomAD
Global Frequency
0.0 in 100,000
Extremely Rare
ACMG Criteria Applied PM2
This variant is absent or extremely rare in population databases (PM2 criteria applies).

ClinVar

Open
Classification
Unknown
0 publications
Clinical Statement

""

COSMIC Somatic Evidence

Open
COSMIC ID
COSM98455
Recurrence
5 occurrences
PM1 Criteria
Not Applied
COSMIC Database Preview
COSMIC Preview
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Functional Impact & Domains

Functional Domain

Hotspot Status
Not a hotspot
Domain Summary
This variant is not located in a mutational hotspot or critical domain.
Related Variants in This Domain
No evidence of other pathogenic variants at this position in gene KRAS.

Functional Studies & Therapeutic Relevance

Functional Summary

The KRAS R68S variant has been functionally characterized as a gain-of-function mutation. In vitro studies using a Novellus FACT assay with Ba/F3 cells expressing KRAS R68S demonstrate that this mutation is activating, as evidenced by increased MAPK signaling compared to the wildtype. This suggests a likely oncogenic effect.

Database Previews
OncoKB
OncoKB Preview
JAX-CKB
JAX-CKB Preview

Click on previews to view full database entries. External databases may require institutional access.

Computational Analysis

Pathogenicity Predictions

SpliceAI
Predictor Consensus
Mixed/VUS
PP3 Applied
Yes
REVEL Score
0.788
Threshold: ≥0.75 = PP3 applied

SpliceAI Scores

Window: ±500bp
Effect Type Score Position
- Acceptor Loss (AL) 0.0 113 bp
- Donor Loss (DL) 0.14 26 bp
+ Acceptor Gain (AG) 0.01 92 bp
+ Donor Gain (DG) 0.01 -5 bp
High impact (≥0.5) Medium impact (0.2-0.49) Low impact (<0.2)

VCEP Guidelines

Applied ACMG/AMP Criteria (VCEP Specific)

Filter Criteria:
PVS1

PVS1 (Not Applied)

According to standard ACMG guidelines, the rule for PVS1 is: 'Null variant (nonsense, frameshift, canonical ±1 or 2 splice sites, initiation codon, single or multi-exon deletion) in a gene where loss-of-function is a known mechanism of disease.' The evidence for this variant shows: a missense (R68S) change which is not a null variant. Therefore, this criterion is not applied.

PS1

PS1 (Not Applied)

According to VCEP guidelines, the rule for PS1 is: 'Strong Same amino acid change as a previously established pathogenic variant regardless of nucleotide change.' The evidence for this variant shows: p.R68S is a novel amino acid change at codon 68 and there is no previously established pathogenic variant with the same amino acid change. Therefore, this criterion is not applied.

PS2

PS2 (Not Applied)

According to VCEP guidelines, the rule for PS2 is: 'Very Strong: 4 Points; Strong: 2 Points; Moderate: 1 Point depending on confirmation of de novo status.' The evidence for this variant shows: no data on de novo occurrence. Therefore, this criterion is not applied.

PS3

PS3 (Supporting)

According to VCEP guidelines, the rule for PS3 is: 'Supporting Strength: Supporting One approved assay. Modification Type: Disease-specific,Gene-specific,Strength.' The evidence for this variant shows: one approved functional assay (Novellus FACT assay) demonstrating increased MAPK signaling due to KRAS R68S gain-of-function. Therefore, this criterion is applied at Supporting strength because one approved functional assay supports a damaging effect.

PS4

PS4 (Not Applied)

According to VCEP guidelines, the rule for PS4 is: 'Strong: ≥5 points; Moderate: ≥3 points; Supporting: ≥1 point based on case-control data.' The evidence for this variant shows: no case-control or prevalence data. Therefore, this criterion is not applied.

PM1

PM1 (Not Applied)

According to VCEP guidelines, the rule for PM1 is: 'Moderate Strength: Applicable only to critical and well-established functional domains available in the supplementary table (P-loop [AA 10-17], SW1 [AA 25-40], SW2 [AA 57-64], SAK [AA 145-156]).' The evidence for this variant shows: codon 68 is outside these domains. Therefore, this criterion is not applied.

PM2

PM2 (Supporting)

According to VCEP guidelines, the rule for PM2 is: 'Supporting Strength: The variant must be absent from controls (gnomAD).' The evidence for this variant shows: not observed in gnomAD (MAF=0). Therefore, this criterion is applied at Supporting strength.

PM3

PM3 (Not Applied)

According to standard ACMG guidelines, the rule for PM3 is: 'For recessive disorders, detected in trans with a pathogenic variant in multiple patients.' The evidence for this variant shows: KRAS-associated conditions are dominant and no trans data. Therefore, this criterion is not applied.

PM4

PM4 (Not Applied)

According to standard ACMG guidelines, the rule for PM4 is: 'Protein length changes due to in-frame indels in non-repeat regions.' The evidence for this variant shows: missense change, no protein length change. Therefore, this criterion is not applied.

PM5

PM5 (Moderate)

According to VCEP guidelines, the rule for PM5 is: 'Moderate Strength: 1 [likely] pathogenic residue change at the same codon. Modification Type: Analogous Gene,Disease-specific.' The evidence for this variant shows: another missense change at codon 68 has been previously established as pathogenic. Therefore, this criterion is applied at Moderate strength.

PM6

PM6 (Not Applied)

According to VCEP guidelines, the rule for PM6 is: 'Moderate 1 Point; Supporting 0.5 Points for assumed de novo without confirmation.' The evidence for this variant shows: no data on de novo occurrence. Therefore, this criterion is not applied.

PP1

PP1 (Not Applied)

According to VCEP guidelines, the rule for PP1 is: 'Supporting Strength: ≥3 informative meioses; Moderate Strength: ≥5; Strong Strength: ≥7.' The evidence for this variant shows: no segregation data. Therefore, this criterion is not applied.

PP2

PP2 (Not Applied)

According to standard ACMG guidelines, the rule for PP2 is: 'Missense variant in a gene with low rate of benign missense and where missense variants are a common mechanism of disease.' The evidence for this variant shows: although missense is a mechanism, data on benign missense rate is insufficient. Therefore, this criterion is not applied.

PP3

PP3 (Supporting)

According to VCEP guidelines, the rule for PP3 is: 'Supporting Strength: For missense variants: REVEL ≥0.7.' The evidence for this variant shows: REVEL score of 0.79. Therefore, this criterion is applied at Supporting strength.

PP4

PP4 (Not Applied)

According to standard ACMG guidelines, the rule for PP4 is: 'Patient's phenotype or family history is highly specific for a disease with a single genetic etiology.' The evidence for this variant shows: no phenotype information provided. Therefore, this criterion is not applied.

PP5

PP5 (Not Applied)

According to standard ACMG guidelines, the rule for PP5 is: 'Reputable source reports variant as pathogenic but without available evidence.' The evidence for this variant shows: no such reports. Therefore, this criterion is not applied.

BA1

BA1 (Not Applied)

According to standard ACMG guidelines, the rule for BA1 is: 'Allele frequency ≥0.05% in population databases.' The evidence for this variant shows: MAF=0. Therefore, this criterion is not applied.

BS1

BS1 (Not Applied)

According to VCEP guidelines, the rule for BS1 is: 'Strong Strength: GnomAD filtering allele frequency ≥0.025%.' The evidence for this variant shows: MAF=0. Therefore, this criterion is not applied.

BS2

BS2 (Not Applied)

According to standard ACMG guidelines, the rule for BS2 is: 'Observed in multiple healthy adult individuals.' The evidence for this variant shows: no such observations. Therefore, this criterion is not applied.

BS3

BS3 (Not Applied)

According to standard ACMG guidelines, the rule for BS3 is: 'Well-established functional studies show no damaging effect on protein function.' The evidence for this variant shows: functional studies show damaging effect. Therefore, this criterion is not applied.

BS4

BS4 (Not Applied)

According to standard ACMG guidelines, the rule for BS4 is: 'Lack of segregation in affected family members.' The evidence for this variant shows: no segregation data. Therefore, this criterion is not applied.

BP1

BP1 (Not Applied)

According to VCEP guidelines, the rule for BP1 is: 'Supporting Strength: For truncating variants in genes without established LOF mechanism and contraindicated for RASopathies.' The evidence for this variant shows: missense variant. Therefore, this criterion is not applied.

BP2

BP2 (Not Applied)

According to standard ACMG guidelines, the rule for BP2 is: 'Observed in cis with another pathogenic variant for a dominant disorder.' The evidence for this variant shows: no such data. Therefore, this criterion is not applied.

BP3

BP3 (Not Applied)

According to standard ACMG guidelines, the rule for BP3 is: 'In-frame deletions/insertions in repetitive region without known function.' The evidence for this variant shows: missense variant. Therefore, this criterion is not applied.

BP4

BP4 (Not Applied)

According to VCEP guidelines, the rule for BP4 is: 'Supporting Strength: For missense variants: REVEL ≤0.3.' The evidence for this variant shows: REVEL score of 0.79. Therefore, this criterion is not applied.

BP5

BP5 (Not Applied)

According to standard ACMG guidelines, the rule for BP5 is: 'Variant found in a case with an alternate molecular basis for disease.' The evidence for this variant shows: no such information. Therefore, this criterion is not applied.

BP6

BP6 (Not Applied)

According to standard ACMG guidelines, the rule for BP6 is: 'Reputable source reports variant as benign but without evidence.' The evidence for this variant shows: no such reports. Therefore, this criterion is not applied.

BP7

BP7 (Not Applied)

According to standard ACMG guidelines, the rule for BP7 is: 'Synonymous variant with no predicted splicing impact and nucleotide not conserved.' The evidence for this variant shows: missense change. Therefore, this criterion is not applied.