Is TH p.Ala418= (c.1254C>G) pathogenic?

TH p.Ala418= (c.1254C>G) is classified Likely benign in TH (ClinVar, Single submitter, 1 submitter; last evaluated 2025-07-31). Very rare (popmax 0.0011%, sas); Associated with TH-deficient dopa-responsive dystonia.

What condition is associated with TH p.Ala418= (c.1254C>G)?

TH p.Ala418= (c.1254C>G) is associated with TH-deficient dopa-responsive dystonia (ClinVar).

How common is TH p.Ala418= (c.1254C>G) in the general population?

TH p.Ala418= (c.1254C>G) is very rare (popmax 0.0011%, sas) (gnomAD).

How is Autosomal recessive dopa-responsive dystonia inherited?

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

TH p.Ala418=

c.1254C>G · VCV4724558

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 0.0011%, sas)

Conditions

TH-deficient dopa-responsive dystonia

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 -7.9	GERP -3.4
Overall
CADD	0.296	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.0011% South Asian · 1/91,070 alleles

Overall 6.2e-05% 1/1,612,636 alleles · very rare exomes 1/1,460,372 · genomes 0/152,264 · joint denominator

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: TH
Protein: p.Ala418=
Coding: c.1254C>G
MANE Select: NM_000360
Type: single nucleotide variant
Location: chr11:2165312 (GRCh38)
Gene constraint: LOEUF 1.27 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 81.75 · 7 PDB
Residue 418: a β-strand

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

Disease context

TH-deficient dopa-responsive dystonia — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Autosomal recessive dopa-responsive dystonia (Orphanet):

Inheritance: Autosomal recessive
Onset: Infancy, Neonatal

Similar variants

TH p.Ala418fs Pathogenic ★ same residue
TH c.1200+2T>C Likely pathogenic ★★ same condition
TH c.1334+1G>A Likely pathogenic ★★ same condition
TH c.312+1G>A Likely pathogenic ★★ same condition
TH c.488-1G>A Pathogenic ★★ same condition
TH c.644+1G>A Likely pathogenic ★★ same condition
TH c.695+1G>C Likely pathogenic ★★ same condition
TH c.90+10C>T 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/th-p-ala418 (accessed [today's date]).

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