Is APOB p.Cys1422= (c.4265=) pathogenic?

APOB p.Cys1422= (c.4265=) is classified Benign in APOB (ClinVar, Multiple submitters, 6 submitters; last evaluated 2026-02-04). Absent from gnomAD v4.1; Associated with familial hypobetalipoproteinemia 1.

What condition is associated with APOB p.Cys1422= (c.4265=)?

APOB p.Cys1422= (c.4265=) is associated with familial hypobetalipoproteinemia 1, hypercholesterolemia, autosomal dominant, type B (ClinVar).

How common is APOB p.Cys1422= (c.4265=) in the general population?

APOB p.Cys1422= (c.4265=) is absent from gnomAD v4.1 (gnomAD).

APOB p.Cys1422=

c.4265= · VCV1168906

Benign Multiple submitters

Classification

Benign

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 6 submitters

gnomAD v4.1

Absent

absent from gnomAD v4.1

Conditions

familial hypobetalipoproteinemia 1

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 0.95	GERP -0.096, phastCons 0.029

Population frequency

gnomAD v4.1 · exomes + genomes

Absent from gnomAD v4.1. Not observed in any sequenced alleles — a rarity signal (ACMG PM2-supporting), not evidence of pathogenicity on its own.

Variant & gene context

Gene: APOB
Protein: p.Cys1422=
Coding: c.4265=
MANE Select: NM_000384
Type: Variation
Location: chr2:21012603 (GRCh38)
Gene constraint: LOEUF 0.537 · pLI <0.01 · ClinGen HI 3/3 (gnomAD)
Residue 1422: a UniProt-annotated variant site (in)

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

Disease context

familial hypobetalipoproteinemia 1 — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Also linked: hypercholesterolemia, autosomal dominant, type B

Similar variants

APOB p.Cys1422Tyr Conflicting classifications of pathogenicity ★ same residue
APOB p.Cys1422Arg Likely benign ★ ⚠ same residue
APOB c.1830-1G>A Pathogenic ★★ same condition
APOB c.226_237+1del Pathogenic/Likely pathogenic ★★ same condition
APOB c.2604+1G>A Likely pathogenic ★★ same condition
APOB c.537+1G>T Pathogenic/Likely pathogenic ★★ same condition
APOB c.78_82+5del Likely pathogenic ★★ same condition
APOB p.Arg1333Ter 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/apob-p-cys1422 (accessed [today's date]).

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