Is BLM p.Ile406= (c.1218A>C) pathogenic?

BLM p.Ile406= (c.1218A>C) is classified Likely benign in BLM (ClinVar, Single submitter, 1 submitter; last evaluated 2023-09-03). Very rare (popmax 0.000254%, nfe); Associated with Bloom syndrome.

What condition is associated with BLM p.Ile406= (c.1218A>C)?

BLM p.Ile406= (c.1218A>C) is associated with Bloom syndrome (ClinVar).

How common is BLM p.Ile406= (c.1218A>C) in the general population?

BLM p.Ile406= (c.1218A>C) is very rare (popmax 0.000254%, nfe) (gnomAD).

How is Bloom syndrome inherited?

Typically Autosomal recessive (Orphanet). A genetic counselor can assess individual risk for a family.

BLM p.Ile406=

c.1218A>C · rs1167576425 · VCV2824625

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 0.000254%, nfe)

Conditions

Bloom syndrome

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Splicing
SpliceAI	<0.2	all four deltas below 0.2 · A>T here scores Δ0.53 · evaluated, not missing
Constraint at this position
Conservation	phyloP -0.17	GERP -4.1
Overall
CADD	5.676	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.000254% European (non-Finnish) · 3/1,180,016 alleles

Filtering AF 6.8e-05% ClinGen BA1/BS1 input FAF95, joint · FAF99 1.9e-05%

Overall 0.000205% 3/1,461,758 alleles · very rare

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.Ile406=
Coding: c.1218A>C
MANE Select: NM_000057
dbSNP: rs1167576425
Type: single nucleotide variant
Location: chr15:90760277 (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 406: an α-helix; the 'necessary for interaction with spidr' region; the 'necessary for dimerization and homooligomerization' region

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

Disease context

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

For Bloom syndrome (Orphanet):

Inheritance: Autosomal recessive
Onset: Antenatal, Neonatal
Prevalence: 1-9 / 100 000 (Specific population)

Similar variants

BLM p.Ile406Thr Uncertain significance ★★ ⚠ same residue
BLM p.Ile406Val Conflicting classifications of pathogenicity ★ ⚠ same residue
BLM c.1087+1G>A Likely pathogenic ★★ same condition
BLM c.1088-1G>A Likely pathogenic ★★ same condition
BLM c.1220+2T>C Likely pathogenic ★★ same condition
BLM c.1220+2T>G Likely pathogenic ★★ same condition
BLM c.1882+2T>C Likely pathogenic ★★ same condition
BLM c.2074+1G>T 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-ile406 (accessed [today's date]).

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