Is ALG8 p.Ser216Cys (c.647C>G) pathogenic?

ALG8 p.Ser216Cys (c.647C>G) is classified Uncertain significance in ALG8 (ClinVar, Single submitter, 1 submitter; last evaluated 2018-01-13). AlphaMissense: likely benign (0.0881); Very rare (popmax 6.84e-05%); Associated with ALG8-congenital disorder of glycosylation.

What condition is associated with ALG8 p.Ser216Cys (c.647C>G)?

ALG8 p.Ser216Cys (c.647C>G) is associated with ALG8-congenital disorder of glycosylation (ClinVar).

How common is ALG8 p.Ser216Cys (c.647C>G) in the general population?

ALG8 p.Ser216Cys (c.647C>G) is very rare (popmax 6.84e-05%) (gnomAD).

How is ALG8-CDG inherited?

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

What do computational predictors say about ALG8 p.Ser216Cys (c.647C>G)?

AlphaMissense predicts likely benign (score 0.0881) — an in-silico prediction, not a clinical call.

ALG8 p.Ser216Cys

c.647C>G · rs886048687 · VCV306221

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely benign

0.0881 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 6.84e-05%)

Missense predictors

0/2 damaging

AlphaMissense, SaProt · REVEL no call

Conditions

ALG8-congenital disorder of glycosylation

Computational evidence

Protein change
AlphaMissense	0.0881	likely benign
REVEL	0.628	indeterminate
SaProt	LLR -6.20	tolerated
⇒ AlphaMissense and SaProt both call this tolerated; REVEL makes no call.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 12	GERP 2.3, phastCons 1
Regional constraint	o/e 0.94	unconstrained · MANE · 39 kb · p 0.14 · regional, not allelic
Overall
CADD	23.1	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 6.84e-05%

Overall 6.84e-05% 1/1,461,796 alleles · very rare

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: ALG8
Protein: p.Ser216Cys
Coding: c.647C>G
MANE Select: NM_024079
dbSNP: rs886048687
Type: single nucleotide variant
Location: chr11:78114292 (GRCh38)
Gene constraint: LOEUF 0.909 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 92.07
Residue 216: a UniProt-annotated variant site (in pcld3)

Full ALG8 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

ALG8-congenital disorder of glycosylation — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For ALG8-CDG (Orphanet):

Inheritance: Autosomal recessive
Onset: Antenatal, Infancy, Neonatal

Similar variants

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ALG8 c.777+1G>A Likely pathogenic ★★ same condition
ALG8 c.95+1G>A Likely pathogenic ★★ same condition
ALG8 p.Arg179Ter Pathogenic/Likely pathogenic ★★ same condition
ALG8 p.Arg229Ter Pathogenic/Likely pathogenic ★★ same condition
ALG8 p.Arg268Ter Pathogenic/Likely pathogenic ★★ same condition
ALG8 p.Arg364Ter Pathogenic/Likely 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/alg8-p-ser216cys (accessed [today's date]).

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