Is HEXA p.Arg166= (c.498C>T) pathogenic?

HEXA p.Arg166= (c.498C>T) is classified Likely benign in HEXA (ClinVar, Single submitter, 1 submitter; last evaluated 2022-02-18). Absent from gnomAD v4.1; Associated with Tay-Sachs disease.

What condition is associated with HEXA p.Arg166= (c.498C>T)?

HEXA p.Arg166= (c.498C>T) is associated with Tay-Sachs disease (ClinVar).

How common is HEXA p.Arg166= (c.498C>T) in the general population?

HEXA p.Arg166= (c.498C>T) is absent from gnomAD v4.1 (gnomAD).

How is Tay-Sachs disease inherited?

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

HEXA p.Arg166=

c.498C>T · rs2542532702 · VCV2098565

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Absent

absent from gnomAD v4.1

Conditions

Tay-Sachs disease

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Splicing
SpliceAI	<0.2	no splice effect predicted · four deltas, not one · how we know
Constraint at this position
Conservation	phyloP 2.8	GERP -0.14, phastCons 1
Overall
CADD	9.456	PHRED · no single calibrated threshold — expert panels disagree

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: HEXA
Protein: p.Arg166=
Coding: c.498C>T
MANE Select: NM_000520
dbSNP: rs2542532702
Type: single nucleotide variant
Location: chr15:72353140 (GRCh38)
Gene constraint: LOEUF 0.947 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 93.62 · 2 PDB
Residue 166: a UniProt-annotated variant site (in gm2g1; late infantile)

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

Disease context

Tay-Sachs disease — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Tay-Sachs disease (Orphanet):

Inheritance: Autosomal recessive
Onset: All ages
Prevalence: 1-5 / 10 000 (Specific population)

Similar variants

HEXA p.Arg166Cys Uncertain significance ★★ ⚠ same residue
HEXA p.Arg166His Uncertain significance ★★ ⚠ same residue
HEXA p.Arg166fs Pathogenic ★ same residue
HEXA c.1073+1G>A Pathogenic/Likely pathogenic ★★ same condition
HEXA c.1330+1G>A Pathogenic ★★ same condition
HEXA c.1330+2T>C Pathogenic ★★ same condition
HEXA c.1421+1G>C Pathogenic ★★ same condition
HEXA c.1421+1G>T 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/hexa-p-arg166 (accessed [today's date]).

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