Is MTAP p.Ser123Phe (c.368C>T) pathogenic?

MTAP p.Ser123Phe (c.368C>T) is classified Uncertain significance in MTAP (ClinVar, Single submitter, 1 submitter; last evaluated 2025-08-21). AlphaMissense: likely pathogenic (0.878); Very rare (popmax 0.000254%, nfe).

How common is MTAP p.Ser123Phe (c.368C>T) in the general population?

MTAP p.Ser123Phe (c.368C>T) is very rare (popmax 0.000254%, nfe) (gnomAD).

What do computational predictors say about MTAP p.Ser123Phe (c.368C>T)?

AlphaMissense predicts likely pathogenic (score 0.878) — an in-silico prediction, not a clinical call.

MTAP p.Ser123Phe

c.368C>T · VCV4111503

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely pathogenic

0.878 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 0.000254%, nfe)

Missense predictors

2/3 damaging

AlphaMissense, REVEL, SaProt

Computational evidence

Protein change
AlphaMissense	0.878	likely pathogenic
REVEL	0.269	benign-leaning
SaProt	LLR -11.90	damaging
⇒ AlphaMissense and SaProt call this damaging; REVEL does not.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 6	GERP 2, phastCons 1
Regional constraint	o/e 1.02	unconstrained · MANE · 59 kb · p 0.71 · regional, not allelic
Overall
CADD	24.2	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 0.000254% European (non-Finnish) · 3/1,179,930 alleles

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

Overall 0.000205% 3/1,461,728 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: MTAP
Protein: p.Ser123Phe
Coding: c.368C>T
MANE Select: NM_002451
Type: single nucleotide variant
Location: chr9:21837928 (GRCh38)
Gene constraint: LOEUF 1.489 · pLI <0.01 · ClinGen HI 1/3 (gnomAD)
Structure: AlphaFold pLDDT 92.99 · 18 PDB

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

Similar variants

MTAP c.*1453C>T Uncertain significance ★★ same type
MTAP p.Gln75Arg Uncertain significance ★★ ⚠ same type
MTAP c.120+279C>T Benign ★★ same type
MTAP c.121-10T>C Benign ★★ same type
MTAP c.121-140G>A Benign ★★ same type
MTAP c.121-185A>G Benign ★★ same type
MTAP c.121-67A>G Benign ★★ same type
MTAP c.121-76T>C Benign ★★ same type

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/mtap-p-ser123phe (accessed [today's date]).

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