Is DBT p.Ser449Ter (c.1346C>G) pathogenic?

DBT p.Ser449Ter (c.1346C>G) is classified Likely pathogenic in DBT (ClinVar, Single submitter, 1 submitter; last evaluated 2024-03-29). Absent from gnomAD v4.1; Associated with maple syrup urine disease type 2.

What condition is associated with DBT p.Ser449Ter (c.1346C>G)?

DBT p.Ser449Ter (c.1346C>G) is associated with maple syrup urine disease type 2 (ClinVar).

How common is DBT p.Ser449Ter (c.1346C>G) in the general population?

DBT p.Ser449Ter (c.1346C>G) is absent from gnomAD v4.1 (gnomAD).

How is Maple syrup urine disease inherited?

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

DBT p.Ser449Ter

c.1346C>G · rs2524063471 · VCV3065883

Likely pathogenic Single submitter

Classification

Likely pathogenic

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

Consequence

nonsense (stop-gain)

predicted LoF

gnomAD v4.1

Absent

absent from gnomAD v4.1

Conditions

maple syrup urine disease type 2

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Consequence	nonsense (stop-gain)	predicted loss-of-function
NMD	escapes	premature termination codon in the last exon (11 of 11) — the truncated protein is likely expressed. PVS1 input, not an applied code
Splicing
SpliceAI	<0.2	all four deltas below 0.2 · G>T here scores Δ0.31 · evaluated, not missing
Constraint at this position
Conservation	phyloP 12	GERP 2.1, phastCons 1
Overall
CADD	39.0	PHRED · no single calibrated threshold — expert panels disagree

Predicted loss-of-function is descriptive, not an applied PVS1 code.

Population frequency

gnomAD v4.1 · exomes + genomes

Absent from gnomAD v4.1. Not observed in any sequenced alleles — a rarity signal (ACMG PM2-supporting), not evidence of pathogenicity on its own.

Variant & gene context

Gene: DBT
Protein: p.Ser449Ter
Coding: c.1346C>G
MANE Select: NM_001918
dbSNP: rs2524063471
Type: single nucleotide variant
Location: chr1:100196358 (GRCh38)
Gene constraint: LOEUF 1.255 · pLI <0.01 · ClinGen HI gene assoc. with recessive phenotype (gnomAD)
Structure: AlphaFold pLDDT 78.71 · 5 PDB

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

Disease context

maple syrup urine disease type 2 — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Maple syrup urine disease (Orphanet):

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

Similar variants

DBT p.Ser449= Likely benign ★ same residue
DBT c.1018-550A>G Pathogenic/Likely pathogenic ★★ same condition
DBT c.1281+1G>A Pathogenic/Likely pathogenic ★★ same condition
DBT c.51+1G>T Pathogenic/Likely pathogenic ★★ same condition
DBT c.773-2A>G Pathogenic ★★ same condition
DBT p.Arg169Ter Pathogenic/Likely pathogenic ★★ same condition
DBT p.Arg301Cys Pathogenic/Likely pathogenic ★★ ⚠ same condition
DBT p.Arg376Cys 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/dbt-p-ser449ter (accessed [today's date]).

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