Is GLB1 p.Val677= (c.2031A>G) pathogenic?

GLB1 p.Val677= (c.2031A>G) is classified Likely benign in GLB1 (ClinVar, Single submitter, 1 submitter; last evaluated 2021-05-21). Very rare (popmax 0.00133%, afr); Associated with mucopolysaccharidosis type 4B.

What condition is associated with GLB1 p.Val677= (c.2031A>G)?

GLB1 p.Val677= (c.2031A>G) is associated with mucopolysaccharidosis type 4B, GM1 gangliosidosis (ClinVar).

How common is GLB1 p.Val677= (c.2031A>G) in the general population?

GLB1 p.Val677= (c.2031A>G) is very rare (popmax 0.00133%, afr) (gnomAD).

How is Mucopolysaccharidosis type 4 inherited?

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

GLB1 p.Val677=

c.2031A>G · rs909928512 · VCV1077701

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 0.00133%, afr)

Conditions

mucopolysaccharidosis type 4B

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 -6.6	GERP -2.5
Overall
CADD	0.083	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00133% African / African-American · 1/74,916 alleles

Overall 6.2e-05% 1/1,614,062 alleles · very rare exomes 0/1,461,892 · genomes 1/152,170 · joint denominator

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: GLB1
Protein: p.Val677=
Coding: c.2031A>G
MANE Select: NM_000404
dbSNP: rs909928512
Type: single nucleotide variant
Location: chr3:32997048 (GRCh38)
Gene constraint: LOEUF 0.938 · pLI <0.01 · ClinGen HI gene assoc. with recessive phenotype (gnomAD)
Structure: AlphaFold pLDDT 90.19 · 8 PDB
Residue 677: the 'disordered' region

Full GLB1 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

mucopolysaccharidosis type 4B — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Also linked: GM1 gangliosidosis

For Mucopolysaccharidosis type 4 (Orphanet):

Inheritance: Autosomal recessive
Onset: Childhood, Infancy
Prevalence: <1 / 1 000 000 (Sweden)

Similar variants

GLB1 p.Val677Gly Uncertain significance ★ ⚠ same residue
GLB1 c.1144-2A>G Pathogenic/Likely pathogenic ★★ same condition
GLB1 c.1233+1G>A Pathogenic/Likely pathogenic ★★ same condition
GLB1 c.1347+1G>T Likely pathogenic ★★ same condition
GLB1 c.1479+1G>A Pathogenic ★★ same condition
GLB1 c.1480-2A>G Pathogenic ★★ same condition
GLB1 c.245+1G>A Pathogenic ★★ same condition
GLB1 c.396+2T>C 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/glb1-p-val677 (accessed [today's date]).

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