HRAS p.Lys170Ter
c.508A>T · rs372936166 · VCV40447
ClinGen expert panel — RASopathy VCEP
Uncertain Significance for Costello syndrome. Applied ACMG criteria (verbatim):
BS4
Curation rationale (ClinGen, verbatim)
The c.508A>T (p.Lys170Ter) variant in the HRAS gene has been identified in patients with cancer and individuals who underwent testing for RASopathies, however it was also identified in an unaffected parent (BS4; Invitae, GeneDx internal data, GTR Lab ID: 26957, 500031; SCV000207840.14, SCV000635092.3). The filtering allele frequency of the p.Lys170Ter variant is 0.0034% for European (non-Finnish) chromosomes by the gnomAD aggregation database (8/249358 with 95% CI), which is not a high enough frequency to meet thresholds defined by the ClinGen RASopahty Expert panel for autosomal dominant RASopathy variants (BA1/BS1 not met). Furthermore, LOF and/or haploinsufficiency has not been clearly identified as disease mechanisms for these genes relative to the RASopathy spectrum phenotype, therefore the PVS1 rule is not applicable. In summary, the clinical significance of the p.Lys170Ter variant is uncertain. RASopathy-specific ACMG/AMP criteria applied (PMID:29493581): BS4.
ClinGen Evidence Repository → · reported verbatim, not re-tallied by Sugi Variant.
Computational evidence
| Protein change | ||
| Missense predictors do not apply to this variant type; conservation carries the signal. | ||
| Consequence | nonsense (stop-gain) | predicted loss-of-function |
|---|---|---|
| NMD | predicted | premature termination codon in exon 5 of 6 |
| Splicing | ||
| SpliceAI | — | not assessed · no allele here is in the release |
| Constraint at this position | ||
| Conservation | phyloP 7.7 | GERP 7.7, phastCons 1 |
| Overall | ||
| CADD | 42.0 | PHRED · no single calibrated threshold — expert panels disagree |
Predicted loss-of-function is descriptive, not an applied PVS1 code.
Population frequency
Rarity supports pathogenicity (ACMG PM2); frequency above a disease-specific BA1/BS1 threshold argues against it. A variant frequent in one ancestry group can be near-absent in others, so a single global figure can mislead.
Variant & gene context
- Gene
- HRAS
- Protein
- p.Lys170Ter
- Coding
- c.508A>T
- MANE Select
- NM_005343
- dbSNP
- rs372936166
- Type
- single nucleotide variant
- Location
- chr11:532698 (GRCh38)
- Gene constraint
- LOEUF 0.893 · pLI 0.02 · ClinGen HI 0/3 (gnomAD)
- Structure
- AlphaFold pLDDT 92.50 · 256 PDB
- Residue 170
- a cross-link site; the 'hypervariable region' region
Similar variants
- HRAS p.Lys170= Likely benign ★★★ same residue
- HRAS p.Lys170Arg Uncertain significance ★ ⚠ same residue
- HRAS p.Ala59Thr Likely pathogenic ★★★ same condition
- HRAS p.Gly12Ser Pathogenic ★★★ same condition
- HRAS p.Gly13Cys Pathogenic ★★★ same condition
- HRAS p.Lys117Arg Pathogenic ★★★ same condition
- HRAS p.Thr58Ile Pathogenic ★★★ same condition
- HRAS p.Gly138Ser Uncertain significance ★★★ ⚠ same condition
Built on 18 open, versioned datasets — ClinVar, gnomAD, AlphaMissense, REVEL, ClinGen & more — plus Sugi Variant's own cross-source analysis. Source data 2026-01–2026-10, ClinVar 2026-10. Full sources & versions →
Cite Sugi Variant
Gür T. Sugi Variant: A Deterministic Per-Variant Germline Reference from a Knowledge Graph for Humans and AI Agents. 2026. doi:10.5281/zenodo.21509445. This variant: https://sugi.bio/variant/hras-p-lys170ter (accessed [today's date]).
Preprint & method: sugi.bio/variant/method Machine-readable: this page as Markdown