Is HLCS p.Ser679= (c.2037C>A) pathogenic?

HLCS p.Ser679= (c.2037C>A) is classified Likely benign in HLCS (ClinVar, Single submitter, 1 submitter; last evaluated 2021-06-03). Very rare (popmax 0.00167%, amr); Associated with holocarboxylase synthetase deficiency.

What condition is associated with HLCS p.Ser679= (c.2037C>A)?

HLCS p.Ser679= (c.2037C>A) is associated with holocarboxylase synthetase deficiency (ClinVar).

How common is HLCS p.Ser679= (c.2037C>A) in the general population?

HLCS p.Ser679= (c.2037C>A) is very rare (popmax 0.00167%, amr) (gnomAD).

How is Holocarboxylase synthetase deficiency inherited?

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

HLCS p.Ser679=

c.2037C>A · rs2145768209 · VCV1563755

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 0.00167%, amr)

Conditions

holocarboxylase synthetase deficiency

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation/SpliceAI carries the signal.
Splicing
SpliceAI	Δ0.26	acceptor gain · deltas
Constraint at this position
Conservation	phyloP 0.94	GERP -1.7, phastCons 1
Overall
CADD	14.1	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00167% Admixed American · 1/60,022 alleles

Overall 0.000124% 2/1,614,152 alleles · very rare

Ancestry group	Frequency	1 in
Admixed Americangrpmax	0.00167%	60,022
European (non-Finnish)	8.47e-05%	1,179,999

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.Ser679=
Coding: c.2037C>A
MANE Select: NM_001352514
dbSNP: rs2145768209
Type: single nucleotide variant
Location: chr21:36765096 (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.Ser679Tyr 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-ser679 (accessed [today's date]).

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