Is BLM p.Ser257Phe (c.770C>T) pathogenic?

BLM p.Ser257Phe (c.770C>T) is classified Likely benign in BLM (ClinVar, Single submitter, 1 submitter; last evaluated 2023-12-07). AlphaMissense: likely benign (0.0838); Very rare (popmax 8.47e-05%, nfe); Associated with hereditary neoplastic syndrome.

What condition is associated with BLM p.Ser257Phe (c.770C>T)?

BLM p.Ser257Phe (c.770C>T) is associated with hereditary neoplastic syndrome (ClinVar).

How common is BLM p.Ser257Phe (c.770C>T) in the general population?

BLM p.Ser257Phe (c.770C>T) is very rare (popmax 8.47e-05%, nfe) (gnomAD).

What do computational predictors say about BLM p.Ser257Phe (c.770C>T)?

AlphaMissense predicts likely benign (score 0.0838) — an in-silico prediction, not a clinical call.

BLM p.Ser257Phe

c.770C>T · rs2151148170 · VCV3224904

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely benign

0.0838 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 8.47e-05%, nfe)

Missense predictors

0/3 damaging

AlphaMissense, REVEL, SaProt

Conditions

hereditary neoplastic syndrome

Computational evidence

Protein change
AlphaMissense	0.0838	likely benign
REVEL	0.078	moderately benign-leaning
SaProt	LLR -7.62	tolerated
⇒ AlphaMissense, REVEL and SaProt all call this tolerated.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 0.35	GERP -0.25
Regional constraint	o/e 0.96	unconstrained · MANE · 16 kb · p 0.23 · regional, not allelic
Overall
CADD	21.4	PHRED · no single calibrated threshold — expert panels disagree

AlphaMissense carries the ACMG weight for missense; REVEL and SaProt are independent agreement signals.

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 8.47e-05% European (non-Finnish) · 1/1,180,028 alleles

Overall 6.2e-05% 1/1,614,116 alleles · very rare exomes 1/1,461,844 · genomes 0/152,272 · joint denominator

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: BLM
Protein: p.Ser257Phe
Coding: c.770C>T
MANE Select: NM_000057
dbSNP: rs2151148170
Type: single nucleotide variant
Location: chr15:90750038 (GRCh38)
Gene constraint: LOEUF 0.847 · pLI <0.01 · ClinGen HI gene assoc. with recessive phenotype (gnomAD)
Structure: AlphaFold pLDDT 61.10 · 16 PDB
Residue 257: the 'disordered' region

Full BLM gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

hereditary neoplastic syndrome — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Similar variants

BLM p.Ser257Pro Uncertain significance ★ ⚠ same residue
BLM c.2075-1G>A Likely pathogenic ★★ same condition
BLM c.2193+1G>A Pathogenic/Likely pathogenic ★★ same condition
BLM c.2308-2A>G Pathogenic/Likely pathogenic ★★ same condition
BLM c.2407-2A>G Likely pathogenic ★★ same condition
BLM c.2555+1G>A Likely pathogenic ★★ same condition
BLM c.2556-2A>G Likely pathogenic ★★ same condition
BLM c.2662+2T>C Likely pathogenic ★★ 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/blm-p-ser257phe (accessed [today's date]).

Preprint & method: sugi.bio/variant/method Machine-readable: this page as Markdown