Is ARSB p.Ala221= (c.663C>T) pathogenic?

ARSB p.Ala221= (c.663C>T) is classified Likely benign in ARSB (ClinVar, Multiple submitters, 2 submitters; last evaluated 2023-11-11). Very rare (popmax 0.00167%, amr); Associated with mucopolysaccharidosis type 6.

What condition is associated with ARSB p.Ala221= (c.663C>T)?

ARSB p.Ala221= (c.663C>T) is associated with mucopolysaccharidosis type 6 (ClinVar).

How common is ARSB p.Ala221= (c.663C>T) in the general population?

ARSB p.Ala221= (c.663C>T) is very rare (popmax 0.00167%, amr) (gnomAD).

How is Mucopolysaccharidosis type 6 inherited?

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

ARSB p.Ala221=

c.663C>T · rs534594272 · VCV1138711

Likely benign Multiple submitters

Classification

Likely benign

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 2 submitters

gnomAD v4.1

Rare

very rare (popmax 0.00167%, amr)

Conditions

mucopolysaccharidosis type 6

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 0.49	GERP -1.8, phastCons 0.72
Overall
CADD	5.773	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00167% Admixed American · 1/60,016 alleles

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

Overall 0.000558% 9/1,613,948 alleles · very rare

Ancestry group	Frequency	1 in
Admixed Americangrpmax	0.00167%	60,016
Remaining individualsnot grpmax-eligible	0.0016%	62,504
European (non-Finnish)	0.000593%	168,555

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: ARSB
Protein: p.Ala221=
Coding: c.663C>T
MANE Select: NM_020427 · reported on NM_000046
dbSNP: rs534594272
Type: single nucleotide variant
Location: chr5:78964443 (GRCh38)
Structure: AlphaFold pLDDT 84.32 · 2 PDB

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

Disease context

mucopolysaccharidosis type 6 — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Mucopolysaccharidosis type 6 (Orphanet):

Inheritance: Autosomal recessive
Onset: Childhood
Prevalence: 1-9 / 1 000 000 (Europe)

Similar variants

ARSB c.1142+1G>A Pathogenic ★★ same condition
ARSB c.1142+1G>T Pathogenic ★★ same condition
ARSB c.1142+2T>A Pathogenic/Likely pathogenic ★★ same condition
ARSB c.1142+2T>C Pathogenic ★★ same condition
ARSB c.1143-1G>A Pathogenic/Likely pathogenic ★★ same condition
ARSB c.1143-1G>C Pathogenic ★★ same condition
ARSB c.1143-8T>G Pathogenic/Likely pathogenic ★★ same condition
ARSB c.1213+6T>C 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/arsb-p-ala221 (accessed [today's date]).

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