Is APOB p.Arg427Ter (c.1279C>T) pathogenic?

APOB p.Arg427Ter (c.1279C>T) is classified Likely pathogenic in APOB (ClinVar, Single submitter, 2 submitters; last evaluated 2022-01-17). Very rare (popmax 0.000339%, nfe); Associated with familial hypobetalipoproteinemia 1.

What condition is associated with APOB p.Arg427Ter (c.1279C>T)?

APOB p.Arg427Ter (c.1279C>T) is associated with familial hypobetalipoproteinemia 1 (ClinVar).

How common is APOB p.Arg427Ter (c.1279C>T) in the general population?

APOB p.Arg427Ter (c.1279C>T) is very rare (popmax 0.000339%, nfe) (gnomAD).

APOB p.Arg427Ter

c.1279C>T · rs1168594259 · VCV827638

Likely pathogenic Single submitter

Classification

Likely pathogenic

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 2 submitters

Consequence

nonsense (stop-gain)

predicted LoF

gnomAD v4.1

Rare

very rare (popmax 0.000339%, nfe)

Conditions

familial hypobetalipoproteinemia 1

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 in a haploinsufficient gene (ClinGen)
NMD	predicted	premature termination codon in exon 10 of 29
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 2.2	GERP 1.5, phastCons 0.029
Overall
CADD	36.0	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 0.000339% European (non-Finnish) · 4/1,180,018 alleles

Filtering AF 7.9e-05% ClinGen BA1/BS1 input FAF95, joint · FAF99 5.4e-05%

Overall 0.000342% 5/1,461,790 alleles · very rare

Ancestry group	Frequency	1 in
Ashkenazi Jewishnot grpmax-eligible	0.00338%	29,608
European (non-Finnish)grpmax	0.000339%	295,004

Ashkenazi Jewish 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: APOB
Protein: p.Arg427Ter
Coding: c.1279C>T
MANE Select: NM_000384
dbSNP: rs1168594259
Type: single nucleotide variant
Location: chr2:21032427 (GRCh38)
Gene constraint: LOEUF 0.537 · pLI <0.01 · ClinGen HI 3/3 (gnomAD)
Residue 427: the vitellogenin domain

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

Similar variants

APOB p.Arg427Gln Conflicting classifications of pathogenicity ★ ⚠ same residue
APOB c.1830-1G>A Pathogenic ★★ same condition
APOB c.2604+1G>A Likely pathogenic ★★ same condition
APOB c.537+1G>T Pathogenic/Likely pathogenic ★★ same condition
APOB p.Arg1333Ter Pathogenic ★★ same condition
APOB p.Arg2012Ter Pathogenic ★★ same condition
APOB p.Arg2085Ter Pathogenic/Likely pathogenic ★★ same condition
APOB p.Arg2513Ter 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-arg427ter (accessed [today's date]).

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