Is DDC p.Ile101= (c.303C>T) pathogenic?

DDC p.Ile101= (c.303C>T) is classified Likely benign in DDC (ClinVar, Single submitter, 1 submitter; last evaluated 2025-10-17). Very rare (popmax 0.00267%, afr); Associated with aromatic L-amino acid decarboxylase deficiency.

What condition is associated with DDC p.Ile101= (c.303C>T)?

DDC p.Ile101= (c.303C>T) is associated with aromatic L-amino acid decarboxylase deficiency (ClinVar).

How common is DDC p.Ile101= (c.303C>T) in the general population?

DDC p.Ile101= (c.303C>T) is very rare (popmax 0.00267%, afr) (gnomAD).

How is Aromatic L-amino acid decarboxylase deficiency inherited?

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

DDC p.Ile101=

c.303C>T · rs779672487 · VCV1610963

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 0.00267%, afr)

Conditions

aromatic L-amino acid decarboxylase deficiency

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
REVEL	0.19	benign-leaning
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP -0.82	GERP -5.1
Overall
CADD	8.26	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00267% African / African-American · 2/74,916 alleles

Filtering AF 0.000689% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.000539%

Overall 0.00112% 18/1,613,498 alleles · very rare exomes 17/1,461,354 · genomes 1/152,144 · joint denominator

Ancestry group	Frequency	1 in
African / African-Americangrpmax	0.00267%	37,458
East Asian	0.00223%	44,862
Remaining individualsnot grpmax-eligible	0.0016%	62,470
European (non-Finnish)	0.00119%	84,266

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: DDC
Protein: p.Ile101=
Coding: c.303C>T
MANE Select: NM_001082971
dbSNP: rs779672487
Type: single nucleotide variant
Location: chr7:50539927 (GRCh38)
Gene constraint: LOEUF 0.922 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 96.88 · 8 PDB
Residue 101: the '2 x approximate tandem repeats' region

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

Disease context

aromatic L-amino acid decarboxylase deficiency — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Aromatic L-amino acid decarboxylase deficiency (Orphanet):

Inheritance: Autosomal recessive
Onset: Infancy, Neonatal

Similar variants

DDC c.1041+1G>A Pathogenic/Likely pathogenic ★★ same condition
DDC c.201+1G>C Likely pathogenic ★★ same condition
DDC c.201+5G>C Pathogenic/Likely pathogenic ★★ same condition
DDC c.714+4A>T Pathogenic ★★ same condition
DDC p.Ala275Thr Pathogenic/Likely pathogenic ★★ same condition
DDC p.Ala91Val Pathogenic/Likely pathogenic ★★ same condition
DDC p.Arg160Trp Pathogenic/Likely pathogenic ★★ same condition
DDC p.Arg347Gln 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/ddc-p-ile101 (accessed [today's date]).

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