Is FTCD p.Arg446Gln (c.1337G>A) pathogenic?

FTCD p.Arg446Gln (c.1337G>A) is classified Benign in FTCD (ClinVar, Single submitter, 1 submitter; last evaluated 2025-12-31). AlphaMissense: likely benign (0.0684); Low-frequency (popmax 2.46%, eas); Associated with formiminoglutamic aciduria.

What condition is associated with FTCD p.Arg446Gln (c.1337G>A)?

FTCD p.Arg446Gln (c.1337G>A) is associated with formiminoglutamic aciduria (ClinVar).

How common is FTCD p.Arg446Gln (c.1337G>A) in the general population?

FTCD p.Arg446Gln (c.1337G>A) is low-frequency (popmax 2.46%, eas) (gnomAD).

How is Formiminoglutamic aciduria inherited?

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

What do computational predictors say about FTCD p.Arg446Gln (c.1337G>A)?

AlphaMissense predicts likely benign (score 0.0684) — an in-silico prediction, not a clinical call.

FTCD p.Arg446Gln

c.1337G>A · rs79021510 · VCV340419

Benign Single submitter

Classification

Benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely benign

0.0684 · ACMG-weighted

gnomAD v4.1

Rare

low-frequency (popmax 2.46%, eas)

Missense predictors

0/3 damaging

AlphaMissense, REVEL, SaProt

Conditions

formiminoglutamic aciduria

Computational evidence

Protein change
AlphaMissense	0.0684	likely benign
REVEL	0.014	strongly benign-leaning
SaProt	LLR -6.85	tolerated
⇒ AlphaMissense, REVEL and SaProt all call this tolerated.
Splicing
SpliceAI	<0.2	no splice effect predicted · four deltas, not one · how we know
Constraint at this position
Conservation	phyloP -2.4	GERP -3
Regional constraint	o/e 1.12	unconstrained · MANE · 19 kb · p 0.00063 · regional, not allelic
Overall
CADD	1.251	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 2.46% East Asian · 1,096/44,590 alleles

Filtering AF 2.34% ClinGen BA1/BS1 input FAF95, joint · FAF99 2.29%

Overall 0.0898% 1,431/1,593,162 alleles · low-frequency exomes 1,245/1,440,842 · genomes 186/152,320 · joint denominator

Ancestry group	Frequency	1 in
East Asiangrpmax	2.46%	41
South Asian	0.182%	549
Remaining individualsnot grpmax-eligible	0.163%	614
African / African-American	0.0374%	2,676
Admixed American	0.0153%	6,534
European (non-Finnish)	0.0028%	35,662

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: FTCD
Protein: p.Arg446Gln
Coding: c.1337G>A
MANE Select: NM_206965
dbSNP: rs79021510
Type: single nucleotide variant
Location: chr21:46138614 (GRCh38)
Gene constraint: LOEUF 1.61 · pLI <0.01 · ClinGen HI gene assoc. with recessive phenotype (gnomAD)
Structure: AlphaFold pLDDT 95.30
Residue 446: the 'cyclodeaminase/cyclohydrolase' region

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

Disease context

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

For Formiminoglutamic aciduria (Orphanet):

Inheritance: Autosomal recessive
Onset: Childhood

Similar variants

FTCD p.Arg446Trp Uncertain significance ★★ ⚠ same residue
FTCD p.Arg255Ter Pathogenic ★★ same condition
FTCD p.Arg71Ter Pathogenic/Likely pathogenic ★★ same condition
FTCD p.Leu536Ter Pathogenic/Likely pathogenic ★★ same condition
FTCD p.Ala108Thr Uncertain significance ★★ ⚠ same condition
FTCD p.Ala159Val Uncertain significance ★★ ⚠ same condition
FTCD p.Ala368Val Uncertain significance ★★ ⚠ same condition
FTCD p.Ala418Thr Uncertain significance ★★ ⚠ 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/ftcd-p-arg446gln (accessed [today's date]).

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