Is MTR p.Ala778Val (c.2333C>T) pathogenic?

MTR p.Ala778Val (c.2333C>T) is classified Uncertain significance in MTR (ClinVar, Single submitter, 1 submitter; last evaluated 2021-12-02). AlphaMissense: likely pathogenic (0.9638); Absent from gnomAD v4.1; Associated with methylcobalamin deficiency type cblG.

What condition is associated with MTR p.Ala778Val (c.2333C>T)?

MTR p.Ala778Val (c.2333C>T) is associated with methylcobalamin deficiency type cblG (ClinVar).

How common is MTR p.Ala778Val (c.2333C>T) in the general population?

MTR p.Ala778Val (c.2333C>T) is absent from gnomAD v4.1 (gnomAD).

How is Homocystinuria without methylmalonic aciduria inherited?

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

What do computational predictors say about MTR p.Ala778Val (c.2333C>T)?

AlphaMissense predicts likely pathogenic (score 0.9638) — an in-silico prediction, not a clinical call.

MTR p.Ala778Val

c.2333C>T · rs2103313543 · VCV1434687

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely pathogenic

0.9638 · ACMG-weighted

gnomAD v4.1

Absent

absent from gnomAD v4.1

Missense predictors

3/3 damaging

AlphaMissense, REVEL, SaProt

Conditions

methylcobalamin deficiency type cblG

Computational evidence

Protein change
AlphaMissense	0.9638	likely pathogenic
REVEL	0.802	moderately pathogenic-leaning
SaProt	LLR -15.36	damaging
⇒ AlphaMissense, REVEL and SaProt all call this damaging.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 7.6	GERP 1.6, phastCons 1
Regional constraint	o/e 0.81	unconstrained · MANE · 102 kb · p 9.3e-14 · regional, not allelic
Overall
CADD	31.0	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: MTR
Protein: p.Ala778Val
Coding: c.2333C>T
MANE Select: NM_000254
dbSNP: rs2103313543
Type: single nucleotide variant
Location: chr1:236863482 (GRCh38)
Gene constraint: LOEUF 0.625 · pLI <0.01 · ClinGen HI gene assoc. with recessive phenotype (gnomAD)
Structure: AlphaFold pLDDT 87.60 · 9 PDB
Residue 778: the b12-binding domain

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

Disease context

methylcobalamin deficiency type cblG — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Homocystinuria without methylmalonic aciduria (Orphanet):

Inheritance: Autosomal recessive
Onset: All ages

Similar variants

MTR c.1812+1G>A Likely pathogenic ★★ same condition
MTR c.2474-1G>C Pathogenic ★★ same condition
MTR c.2595-2A>G Likely pathogenic ★★ same condition
MTR c.340-166A>G Pathogenic/Likely pathogenic ★★ same condition
MTR c.609+1088G>A Pathogenic ★★ same condition
MTR c.866-2A>C Pathogenic/Likely pathogenic ★★ same condition
MTR p.Arg1147Ter Pathogenic ★★ same condition
MTR p.Arg585Ter Pathogenic/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/mtr-p-ala778val (accessed [today's date]).

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