Is HLCS p.Pro803= (c.2409C>G) pathogenic?

HLCS p.Pro803= (c.2409C>G) is classified Likely benign in HLCS (ClinVar, Single submitter, 1 submitter; last evaluated 2023-04-06). Very rare (popmax 0.00446%, eas); Associated with holocarboxylase synthetase deficiency.

What condition is associated with HLCS p.Pro803= (c.2409C>G)?

HLCS p.Pro803= (c.2409C>G) is associated with holocarboxylase synthetase deficiency (ClinVar).

How common is HLCS p.Pro803= (c.2409C>G) in the general population?

HLCS p.Pro803= (c.2409C>G) is very rare (popmax 0.00446%, eas) (gnomAD).

How is Holocarboxylase synthetase deficiency inherited?

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

HLCS p.Pro803=

c.2409C>G · rs763530346 · VCV1633502

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 0.00446%, eas)

Conditions

holocarboxylase synthetase deficiency

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 0.37	GERP 0.21, phastCons 0.008
Overall
CADD	2.431	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00446% East Asian · 2/44,870 alleles

Filtering AF 0.000739% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.000276%

Overall 0.000186% 3/1,613,814 alleles · very rare exomes 3/1,461,756 · genomes 0/152,058 · joint denominator

Ancestry group	Frequency	1 in
East Asiangrpmax	0.00446%	22,435
European (non-Finnish)	8.48e-05%	1,179,916

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: HLCS
Protein: p.Pro803=
Coding: c.2409C>G
MANE Select: NM_001352514
dbSNP: rs763530346
Type: single nucleotide variant
Location: chr21:36756583 (GRCh38)
Gene constraint: LOEUF 0.883 · pLI <0.01 · ClinGen HI gene assoc. with recessive phenotype (gnomAD)
Structure: AlphaFold pLDDT 77.33

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

Disease context

holocarboxylase synthetase deficiency — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Holocarboxylase synthetase deficiency (Orphanet):

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

Similar variants

HLCS p.Pro803Ser Uncertain significance ★★ ⚠ same residue
HLCS c.1620+2T>G Likely pathogenic ★★ same condition
HLCS c.1621-2A>G Likely pathogenic ★★ same condition
HLCS c.1892+1G>A Likely pathogenic ★★ same condition
HLCS c.1960+5G>A Pathogenic ★★ same condition
HLCS c.2121+1G>A Pathogenic/Likely pathogenic ★★ same condition
HLCS c.2237-2A>G Likely pathogenic ★★ same condition
HLCS c.2450+2T>A 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/hlcs-p-pro803 (accessed [today's date]).

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