Is NPC1 p.His641= (c.1923C>T) pathogenic?

NPC1 p.His641= (c.1923C>T) is classified Likely benign in NPC1 (ClinVar, Single submitter, 1 submitter; last evaluated 2020-05-28). Very rare (popmax 0.00243%, eas); Associated with Niemann-Pick disease, type C1.

What condition is associated with NPC1 p.His641= (c.1923C>T)?

NPC1 p.His641= (c.1923C>T) is associated with Niemann-Pick disease, type C1 (ClinVar).

How common is NPC1 p.His641= (c.1923C>T) in the general population?

NPC1 p.His641= (c.1923C>T) is very rare (popmax 0.00243%, eas) (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.His641=

c.1923C>T · rs758222159 · VCV1144101

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 0.00243%, eas)

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 3.5	GERP 0.97, phastCons 1
Overall
CADD	7.865	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00243% East Asian · 1/41,212 alleles

Filtering AF 3.1e-05% ClinGen BA1/BS1 input FAF95, joint · FAF99 1.2e-05%

Overall 0.000205% 3/1,461,444 alleles · very rare

Ancestry group	Frequency	1 in
East Asiangrpmax	0.00243%	41,212
European (non-Finnish)	0.000189%	529,221

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: NPC1
Protein: p.His641=
Coding: c.1923C>T
MANE Select: NM_000271
dbSNP: rs758222159
Type: single nucleotide variant
Location: chr18:23544984 (GRCh38)
Gene constraint: LOEUF 0.676 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 85.35 · 20 PDB
Residue 641: the ssd domain

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.His641fs Pathogenic/Likely pathogenic ★★ 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-his641 (accessed [today's date]).

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