Is FTCD p.Glu508Ter (c.1522G>T) pathogenic?

FTCD p.Glu508Ter (c.1522G>T) is classified Likely pathogenic in FTCD (ClinVar, Single submitter, 1 submitter; last evaluated 2024-06-21). Very rare (popmax 0.00136%, nfe); Associated with formiminoglutamic aciduria.

What condition is associated with FTCD p.Glu508Ter (c.1522G>T)?

FTCD p.Glu508Ter (c.1522G>T) is associated with formiminoglutamic aciduria (ClinVar).

How common is FTCD p.Glu508Ter (c.1522G>T) in the general population?

FTCD p.Glu508Ter (c.1522G>T) is very rare (popmax 0.00136%, nfe) (gnomAD).

How is Formiminoglutamic aciduria inherited?

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

FTCD p.Glu508Ter

c.1522G>T · VCV3587701

Likely pathogenic Single submitter

Classification

Likely pathogenic

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

Consequence

nonsense (stop-gain)

predicted LoF

gnomAD v4.1

Rare

very rare (popmax 0.00136%, nfe)

Conditions

formiminoglutamic aciduria

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Consequence	nonsense (stop-gain)	predicted loss-of-function
NMD	escapes	premature termination codon within the last 50 nt of the penultimate exon (13 of 14, 17 nt from its 3' end) — the truncated protein is likely expressed. PVS1 input, not an applied code
REVEL	0.149	moderately benign-leaning
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP -0.39	GERP -1.2
Overall
CADD	35.0	PHRED · no single calibrated threshold — expert panels disagree

Predicted loss-of-function is descriptive, not an applied PVS1 code.

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00136% European (non-Finnish) · 16/1,179,246 alleles

Filtering AF 0.000803% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00065%

Overall 0.00105% 17/1,613,152 alleles · very rare exomes 17/1,460,834 · genomes 0/152,318 · joint denominator

Ancestry group	Frequency	1 in
Remaining individualsnot grpmax-eligible	0.0016%	62,476
European (non-Finnish)grpmax	0.00136%	73,703

Remaining individuals shows a higher raw frequency than the grpmax group above it. gnomAD excludes bottlenecked groups — Finnish, Ashkenazi Jewish, Amish and “Remaining individuals” — from grpmax, because founder effects make their frequencies unrepresentative for filtering. The table is sorted by frequency, so an excluded group can sit above the grpmax row.

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.Glu508Ter
Coding: c.1522G>T
MANE Select: NM_206965
Type: single nucleotide variant
Location: chr21:46137256 (GRCh38)
Gene constraint: LOEUF 1.61 · pLI <0.01 · ClinGen HI gene assoc. with recessive phenotype (gnomAD)
Structure: AlphaFold pLDDT 95.30
Residue 508: 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.Glu508Lys 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-glu508ter (accessed [today's date]).

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