Is B2M p.Cys45Trp (c.135C>G) pathogenic?

B2M p.Cys45Trp (c.135C>G) is classified Uncertain significance in B2M (ClinVar, Single submitter, 1 submitter; last evaluated 2023-03-23). AlphaMissense: likely pathogenic (0.9973); Absent from gnomAD v4.1; Associated with hypoproteinemia, hypercatabolic.

What condition is associated with B2M p.Cys45Trp (c.135C>G)?

B2M p.Cys45Trp (c.135C>G) is associated with hypoproteinemia, hypercatabolic (ClinVar).

How common is B2M p.Cys45Trp (c.135C>G) in the general population?

B2M p.Cys45Trp (c.135C>G) is absent from gnomAD v4.1 (gnomAD).

What do computational predictors say about B2M p.Cys45Trp (c.135C>G)?

AlphaMissense predicts likely pathogenic (score 0.9973) — an in-silico prediction, not a clinical call.

B2M p.Cys45Trp

c.135C>G · rs2086930618 · VCV2848870

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely pathogenic

0.9973 · ACMG-weighted

gnomAD v4.1

Absent

absent from gnomAD v4.1

Missense predictors

2/2 damaging

AlphaMissense, SaProt · REVEL no call

Conditions

hypoproteinemia, hypercatabolic

Computational evidence

Protein change
AlphaMissense	0.9973	likely pathogenic · top 1% in B2M
REVEL	0.598	indeterminate
SaProt	LLR -15.28	damaging
⇒ AlphaMissense and SaProt both call this damaging; REVEL makes no call.
Splicing
SpliceAI	Δ0.31	donor gain · deltas
Constraint at this position
Conservation	phyloP 0.84	GERP 0.95, phastCons 1
Overall
CADD	29.0	PHRED · no single calibrated threshold — expert panels disagree

ClinVar classifies this uncertain; the computational predictors unanimously lean damaging — a triage signal, not a reclassification

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

Population frequency

gnomAD v4.1 · exomes + genomes

Absent from gnomAD v4.1. Not observed in any sequenced alleles — a rarity signal (ACMG PM2-supporting), not evidence of pathogenicity on its own.

Variant & gene context

Gene: B2M
Protein: p.Cys45Trp
Coding: c.135C>G
MANE Select: NM_004048
dbSNP: rs2086930618
Type: single nucleotide variant
Location: chr15:44715490 (GRCh38)
Gene constraint: LOEUF 0.501 · pLI 0.97 (gnomAD)
Structure: AlphaFold pLDDT 94.43 · 1396 PDB
Residue 45: a disulfide bond; a β-strand; the ig-like c1-type domain

Full B2M gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

hypoproteinemia, hypercatabolic — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Similar variants

B2M p.Asp54Asn Uncertain significance ★★ ⚠ same condition
B2M p.Ile55Thr Uncertain significance ★★ ⚠ same condition
B2M p.Lys114Gln Uncertain significance ★★ ⚠ same condition
B2M p.Lys68Glu Uncertain significance ★★ ⚠ same condition
B2M p.Pro92Leu Uncertain significance ★★ ⚠ same condition
B2M c.67+12C>T Likely benign ★★ same condition
B2M c.67+19C>T Benign/Likely benign ★★ same condition
B2M c.68-13C>T Likely benign ★★ 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/b2m-p-cys45trp (accessed [today's date]).

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