Is HPD p.Asn259= (c.777C>T) pathogenic?

HPD p.Asn259= (c.777C>T) is classified Likely benign in HPD (ClinVar, Single submitter, 1 submitter; last evaluated 2024-01-31). Very rare (popmax 0.008%, afr); Associated with hawkinsinuria.

What condition is associated with HPD p.Asn259= (c.777C>T)?

HPD p.Asn259= (c.777C>T) is associated with hawkinsinuria, tyrosinemia type III (ClinVar).

How common is HPD p.Asn259= (c.777C>T) in the general population?

HPD p.Asn259= (c.777C>T) is very rare (popmax 0.008%, afr) (gnomAD).

How is Hawkinsinuria inherited?

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

HPD p.Asn259=

c.777C>T · rs201249721 · VCV2929650

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 0.008%, afr)

Conditions

hawkinsinuria

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 -5.1	GERP -3.3
Overall
CADD	2.899	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.008% African / African-American · 6/75,008 alleles

Filtering AF 0.00347% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00228%

Overall 0.00149% 24/1,614,050 alleles · very rare

Ancestry group	Frequency	1 in
African / African-Americangrpmax	0.008%	12,501
Remaining individualsnot grpmax-eligible	0.0016%	62,506
European (non-Finnish)	0.00136%	73,750
South Asian	0.0011%	91,080

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: HPD
Protein: p.Asn259=
Coding: c.777C>T
MANE Select: NM_002150
dbSNP: rs201249721
Type: single nucleotide variant
Location: chr12:121846916 (GRCh38)
Gene constraint: LOEUF 0.845 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 96.00 · 4 PDB
Residue 259: a UniProt-annotated variant site (in tyrsn3; likely pathogenic); the voc 2 domain; an α-helix

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

Disease context

hawkinsinuria — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Also linked: tyrosinemia type III

For Hawkinsinuria (Orphanet):

Inheritance: Autosomal dominant
Onset: Infancy, Neonatal
Prevalence: <1 / 1 000 000 (Worldwide)

Similar variants

HPD p.Arg225Ter Pathogenic/Likely pathogenic ★★ same condition
HPD p.Gln205Ter Pathogenic/Likely pathogenic ★★ same condition
HPD p.Tyr160Cys Likely pathogenic ★★ same condition
HPD p.Ala230Thr Uncertain significance ★★ ⚠ same condition
HPD p.Arg111Trp Uncertain significance ★★ ⚠ same condition
HPD p.Arg119Gln Uncertain significance ★★ ⚠ same condition
HPD p.Arg279Gly Uncertain significance ★★ ⚠ same condition
HPD p.Arg300Trp Uncertain significance ★★ ⚠ 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/hpd-p-asn259 (accessed [today's date]).

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