Is PAH p.Phe402Ile (c.1204T>A) pathogenic?

PAH p.Phe402Ile (c.1204T>A) is classified Uncertain significance in PAH (ClinVar, Expert panel, 1 submitter; last evaluated 2021-05-15). AlphaMissense: likely pathogenic (0.7253); Absent from gnomAD v4.1; Associated with phenylketonuria.

What condition is associated with PAH p.Phe402Ile (c.1204T>A)?

PAH p.Phe402Ile (c.1204T>A) is associated with phenylketonuria (ClinVar).

How common is PAH p.Phe402Ile (c.1204T>A) in the general population?

PAH p.Phe402Ile (c.1204T>A) is absent from gnomAD v4.1 (gnomAD).

How is Phenylketonuria inherited?

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

What do computational predictors say about PAH p.Phe402Ile (c.1204T>A)?

AlphaMissense predicts likely pathogenic (score 0.7253) — an in-silico prediction, not a clinical call.

PAH p.Phe402Ile

c.1204T>A · rs62508725 · VCV1327562

Uncertain significance Expert panel

Classification

Uncertain significance

ClinVar

Review

Expert panel ★★★☆

ClinVar · 1 submitter

AlphaMissense

likely pathogenic

0.7253 · ACMG-weighted

gnomAD v4.1

Absent

absent from gnomAD v4.1

Missense predictors

3/3 damaging

AlphaMissense, REVEL, SaProt

Conditions

phenylketonuria

ClinGen expert panel — Phenylketonuria VCEP

Uncertain Significance for phenylketonuria. Applied ACMG criteria (verbatim):

PM2 PP4_Moderate PP3

Curation rationale (ClinGen, verbatim)

The c.1204T>A (p.Phe402Ile) variant in PAH has been detected in 1 Japanese patient with mild HPA, BH4 deficiency excluded (PMID: 21307867). This variant is absent from population databases (PM2), and is predicted deleterious by SIFT, PolyPhen2, MutationTaster, and REVEL = 0.946 (PP3). In summary, this variant meets criteria to be classified as uncertain significance for PAH. PAH-specific ACMG/AMP criteria applied: PM2, PP3, PP4_M.

ClinGen Evidence Repository → · reported verbatim, not re-tallied by Sugi Variant.

Computational evidence

Protein change
AlphaMissense	0.7253	likely pathogenic
REVEL	0.946	strongly pathogenic-leaning
SaProt	LLR -14.39	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 11	GERP 2.2, phastCons 1
Regional constraint	o/e 1.07	unconstrained · MANE · 78 kb · p 0.12 · regional, not allelic
Overall
CADD	28.4	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: PAH
Protein: p.Phe402Ile
Coding: c.1204T>A
MANE Select: NM_000277
dbSNP: rs62508725
Type: single nucleotide variant
Location: chr12:102840511 (GRCh38)
Gene constraint: LOEUF 1.265 · pLI <0.01 · ClinGen HI gene assoc. with recessive phenotype (gnomAD)
Structure: AlphaFold pLDDT 89.04 · 21 PDB
Residue 402: an α-helix

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

Disease context

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

For Phenylketonuria (Orphanet):

Inheritance: Autosomal recessive
Onset: Infancy
Prevalence: 1-9 / 100 000 (France)

Similar variants

PAH p.Phe402Cys Likely pathogenic ★★★ same residue
PAH p.Phe402Leu Likely pathogenic ★★★ same residue
PAH p.Phe402Val Likely pathogenic ★★★ same residue
PAH c.1065+1G>A Likely pathogenic ★★★ same condition
PAH c.1065+1G>T Likely pathogenic ★★★ same condition
PAH c.1065+3A>G Likely pathogenic ★★★ same condition
PAH c.1066-11G>A Pathogenic ★★★ same condition
PAH c.1066-14C>G 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/pah-p-phe402ile (accessed [today's date]).

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