Is NPC1 p.Arg647= (c.1941G>A) pathogenic?

NPC1 p.Arg647= (c.1941G>A) is classified Likely benign in NPC1 (ClinVar, Single submitter, 1 submitter; last evaluated 2025-11-16). No allele count reported in gnomAD v4.1 (AN 1,513,924); Associated with Niemann-Pick disease, type C1.

What condition is associated with NPC1 p.Arg647= (c.1941G>A)?

NPC1 p.Arg647= (c.1941G>A) is associated with Niemann-Pick disease, type C1 (ClinVar).

How common is NPC1 p.Arg647= (c.1941G>A) in the general population?

NPC1 p.Arg647= (c.1941G>A) is no allele count reported in gnomAD v4.1 (AN 1,513,924) (gnomAD).

How is Niemann-Pick disease type C inherited?

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

NPC1 p.Arg647=

c.1941G>A · rs1333052052 · VCV1131268

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Not reported

no allele count reported in gnomAD v4.1 (AN 1,513,924)

Conditions

Niemann-Pick disease, type C1

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 -0.5	GERP -1.2
Overall
CADD	7.277	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

No allele count reported in gnomAD v4.1 (AN 1,513,924). This is missing data, not an absence: the variant may or may not be present in gnomAD. Rarity (ACMG PM2) and BA1/BS1 cannot be assessed for it.

Variant & gene context

Gene: NPC1
Protein: p.Arg647=
Coding: c.1941G>A
MANE Select: NM_000271
dbSNP: rs1333052052
Type: single nucleotide variant
Location: chr18:23544966 (GRCh38)
Gene constraint: LOEUF 0.676 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 85.35 · 20 PDB
Residue 647: the ssd domain; a turn

Full NPC1 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

Niemann-Pick disease, type C1 — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Niemann-Pick disease type C (Orphanet):

Inheritance: Autosomal recessive
Onset: All ages
Prevalence: 1-9 / 100 000 (Europe)

Similar variants

NPC1 p.Arg647Ser Uncertain significance ★ ⚠ same residue
NPC1 c.1554-1009G>A Pathogenic ★★ same condition
NPC1 c.1757+1G>A Likely pathogenic ★★ same condition
NPC1 c.1947+5G>C Pathogenic/Likely pathogenic ★★ same condition
NPC1 c.2130+1G>A Pathogenic ★★ same condition
NPC1 c.2245+1G>A Pathogenic/Likely pathogenic ★★ same condition
NPC1 c.2246-2A>G Pathogenic/Likely pathogenic ★★ same condition
NPC1 c.2515-2A>G 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/npc1-p-arg647 (accessed [today's date]).

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