Is PAH p.Ala140= (c.420G>T) pathogenic?

PAH p.Ala140= (c.420G>T) is classified Likely benign in PAH (ClinVar, Single submitter, 1 submitter; last evaluated 2023-04-30). Very rare (popmax 0.00223%, eas); Associated with phenylketonuria.

What condition is associated with PAH p.Ala140= (c.420G>T)?

PAH p.Ala140= (c.420G>T) is associated with phenylketonuria (ClinVar).

How common is PAH p.Ala140= (c.420G>T) in the general population?

PAH p.Ala140= (c.420G>T) is very rare (popmax 0.00223%, eas) (gnomAD).

How is Phenylketonuria inherited?

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

PAH p.Ala140=

c.420G>T · rs200366386 · VCV1602103

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 0.00223%, eas)

Conditions

phenylketonuria

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP -20	GERP -4.2
Overall
CADD	0.013	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00223% East Asian · 1/44,860 alleles

Overall 6.84e-05% 1/1,461,712 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: PAH
Protein: p.Ala140=
Coding: c.420G>T
MANE Select: NM_000277
dbSNP: rs200366386
Type: single nucleotide variant
Location: chr12:102877483 (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 140: 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.Ala140Gly Uncertain significance ★ ⚠ same residue
PAH p.Ala140Val Uncertain significance ★ ⚠ same residue
PAH p.Ala140Glu Uncertain significance ★ ⚠ 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-ala140 (accessed [today's date]).

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