Is ABCG8 p.Ala559Ser (c.1675G>T) pathogenic?

ABCG8 p.Ala559Ser (c.1675G>T) is classified Uncertain significance in ABCG8 (ClinVar, Single submitter, 2 submitters; last evaluated 2018-01-13). AlphaMissense: likely benign (0.1015); Very rare (popmax 0.000593%, nfe); Associated with sitosterolemia 1.

What condition is associated with ABCG8 p.Ala559Ser (c.1675G>T)?

ABCG8 p.Ala559Ser (c.1675G>T) is associated with sitosterolemia 1 (ClinVar).

How common is ABCG8 p.Ala559Ser (c.1675G>T) in the general population?

ABCG8 p.Ala559Ser (c.1675G>T) is very rare (popmax 0.000593%, nfe) (gnomAD).

How is Sitosterolemia inherited?

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

What do computational predictors say about ABCG8 p.Ala559Ser (c.1675G>T)?

AlphaMissense predicts likely benign (score 0.1015) — an in-silico prediction, not a clinical call.

ABCG8 p.Ala559Ser

c.1675G>T · rs886056036 · VCV336086

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 2 submitters

AlphaMissense

likely benign

0.1015 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 0.000593%, nfe)

Missense predictors

0/3 damaging

AlphaMissense, REVEL, SaProt

Conditions

sitosterolemia 1

Computational evidence

Protein change
AlphaMissense	0.1015	likely benign
REVEL	0.171	moderately benign-leaning
SaProt	LLR -7.82	tolerated
⇒ AlphaMissense, REVEL and SaProt all call this tolerated.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 3.1	GERP 0.38, phastCons 1
Regional constraint	o/e 1.29	unconstrained · MANE · 39 kb · p 8.8e-18 · regional, not allelic
Overall
CADD	15.31	PHRED · no single calibrated threshold — expert panels disagree

ClinVar classifies this uncertain; the computational predictors unanimously lean tolerated — a triage signal, not a reclassification

AlphaMissense carries the ACMG weight for missense; REVEL and SaProt are independent agreement signals.

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.000593% European (non-Finnish) · 7/1,180,046 alleles

Filtering AF 0.000247% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.000159%

Overall 0.000547% 8/1,461,808 alleles · very rare

Ancestry group	Frequency	1 in
Remaining individualsnot grpmax-eligible	0.0016%	62,508
European (non-Finnish)grpmax	0.000593%	168,578

Remaining individuals 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: ABCG8
Protein: p.Ala559Ser
Coding: c.1675G>T
MANE Select: NM_022437
dbSNP: rs886056036
Type: single nucleotide variant
Location: chr2:43875332 (GRCh38)
Gene constraint: LOEUF 1.329 · pLI <0.01 · ClinGen HI gene assoc. with recessive phenotype (gnomAD)
Structure: AlphaFold pLDDT 80.94 · 8 PDB
Residue 559: the abc transmembrane type-2 domain; an α-helix

Full ABCG8 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

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

For Sitosterolemia (Orphanet):

Inheritance: Autosomal recessive
Onset: All ages

Similar variants

ABCG8 p.Ala559Pro Uncertain significance ★ ⚠ same residue
ABCG8 c.64-2A>G Pathogenic ★★ same condition
ABCG8 c.965-1G>C Pathogenic ★★ same condition
ABCG8 p.Arg164Ter Pathogenic ★★ same condition
ABCG8 p.Arg405Cys Pathogenic/Likely pathogenic ★★ ⚠ same condition
ABCG8 p.Arg412Ter Pathogenic/Likely pathogenic ★★ same condition
ABCG8 p.Gly574Arg Pathogenic/Likely pathogenic ★★ same condition
ABCG8 p.Ser107Ter 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/abcg8-p-ala559ser (accessed [today's date]).

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