Curated summary · agent-written · kb/genes/curated/hgnc_68.md

All 15 claims checked against the KB draft

ABCD4 across dismech

ABCD4 (ATP binding cassette subfamily D member 4) is named by 2 disorder entries: Methylmalonic Acidemia With Homocystinuria, Type cblJ; and Inborn Disorder of Cobalamin Metabolism and Transport.

Normal function

ai-gene-review gives ABCD4's core molecular functions as ABC-type vitamin B12 transporter activity; and ATP hydrolysis activity, acting in cobalamin transport; and cobalamin metabolic process. With its escort LMBD1, ABCD4 exports cobalamin from the lysosome to the cytosol.

Causative record

Methylmalonic Acidemia With Homocystinuria, Type cblJ types ABCD4 as causative, with a germline variant origin. ABCD4 sits on 2 of its nodes, including ABCD4 Variants Disabling the Lysosomal Cobalamin Exporter. ClinGen rates the relationship moderate.

Agreement between the layers

The KB mechanism and the gene review share cobalamin transport.

The grouping-level entry Inborn Disorder of Cobalamin Metabolism and Transport places ABCD4 on a node (Defective cobalamin absorption, transport, and cellular uptake) but has no genetic record for it; the ClinGen-matched entries that do not type ABCD4 are Inborn Disorder of Cobalamin Metabolism and Transport.

Underlined values are claims re-computed from the knowledge base each time this page is built. The tables below are the source of truth.

Normal function · from ai-gene-review (O14678, commit 79fe13b38970) · AI-generated, not KB evidence

ai-gene-review has this gene at status INITIALIZED; the description is shown only once the review is complete. Read the draft upstream.

In the knowledge base · computed from kb/ at build time

Disorders

Relationship is the entry's genetic[].relationship_type. untyped means the entry has a genetic record for the gene but does not type it; its free-text association is shown instead.

Disorder	Relationship	Where the gene appears
Methylmalonic Acidemia With Homocystinuria, Type cblJ	causative germline loss of function CLINGEN: moderate	mechanism: ABCD4 Variants Disabling the Lysosomal Cobalamin Exporter; Failure of the ABCD4-LMBD1 Complex at the Lysosomal Membrane
Inborn Disorder of Cobalamin Metabolism and Transport	no genetic record	mechanism: Defective cobalamin absorption, transport, and cellular uptake subtype: cblJ

ClinGen gene–disease validity · snapshot 2026-10-03 · matched to entries by MONDO

An entry matches when ClinGen's MONDO disease is the entry's own disease term, a subtype term, or an exact-match mapping. An amber status marks an entry ClinGen supports the gene for (Definitive, Strong or Moderate) whose own record does not type it. A Limited, Disputed or Refuted tier on such an entry is not a gap.

ClinGen disease	MOI	Classification	dismech entry
methylmalonic acidemia with homocystinuria, type cblJ MONDO:0013925	AR	Moderate 2026-01-23	Inborn Disorder of Cobalamin Metabolism and Transport no genetic record Methylmalonic Acidemia With Homocystinuria, Type cblJ causative