Is ABCD4 p.Pro303= (c.909C>T) pathogenic?

ABCD4 p.Pro303= (c.909C>T) is classified Likely benign in ABCD4 (ClinVar, Single submitter, 1 submitter; last evaluated 2026-01-09). Ultra-rare (popmax 0.0334%, eas); Associated with methylmalonic acidemia with homocystinuria, type cblJ.

What condition is associated with ABCD4 p.Pro303= (c.909C>T)?

ABCD4 p.Pro303= (c.909C>T) is associated with methylmalonic acidemia with homocystinuria, type cblJ (ClinVar).

How common is ABCD4 p.Pro303= (c.909C>T) in the general population?

ABCD4 p.Pro303= (c.909C>T) is ultra-rare (popmax 0.0334%, eas) (gnomAD).

How is Methylmalonic acidemia with homocystinuria inherited?

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

ABCD4 p.Pro303=

c.909C>T · VCV4762122

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

ultra-rare (popmax 0.0334%, eas)

Conditions

methylmalonic acidemia with homocystinuria, type cblJ

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 1.4	GERP -1.8, phastCons 0.85
Overall
CADD	14.82	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.0334% East Asian · 15/44,870 alleles

Filtering AF 0.0206% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.0166%

Overall 0.00105% 17/1,614,080 alleles · ultra-rare exomes 17/1,461,788 · genomes 0/152,292 · joint denominator

Ancestry group	Frequency	1 in
East Asiangrpmax	0.0334%	2,991
African / African-American	0.00133%	75,038
European (non-Finnish)	8.47e-05%	1,179,976

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: ABCD4
Protein: p.Pro303=
Coding: c.909C>T
MANE Select: NM_005050
Type: single nucleotide variant
Location: chr14:74292775 (GRCh38)
Gene constraint: LOEUF 0.772 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 87.18 · 4 PDB
Residue 303: the abc transmembrane type-1 domain

Full ABCD4 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

methylmalonic acidemia with homocystinuria, type cblJ — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Methylmalonic acidemia with homocystinuria (Orphanet):

Inheritance: Autosomal recessive, X-linked recessive
Onset: All ages

Similar variants

ABCD4 c.542+1G>T Pathogenic ★★ same condition
ABCD4 p.Arg432Gln Likely pathogenic ★★ same condition
ABCD4 p.Asn141Lys Pathogenic/Likely pathogenic ★★ same condition
ABCD4 p.Gln530Ter Pathogenic/Likely pathogenic ★★ same condition
ABCD4 p.Tyr176Ter Pathogenic/Likely pathogenic ★★ same condition
ABCD4 c.1028+5G>A Uncertain significance ★★ same condition
ABCD4 c.425+6C>T Uncertain significance ★★ same condition
ABCD4 c.719+6T>C 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/abcd4-p-pro303 (accessed [today's date]).

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