Is DBT p.Ser242Ter (c.725C>G) pathogenic?

DBT p.Ser242Ter (c.725C>G) is classified Pathogenic in DBT (ClinVar, Multiple submitters, 3 submitters; last evaluated 2023-11-28). Very rare (popmax 0.00017%, nfe); Associated with maple syrup urine disease.

What condition is associated with DBT p.Ser242Ter (c.725C>G)?

DBT p.Ser242Ter (c.725C>G) is associated with maple syrup urine disease, maple syrup urine disease type 1A (ClinVar).

How common is DBT p.Ser242Ter (c.725C>G) in the general population?

DBT p.Ser242Ter (c.725C>G) is very rare (popmax 0.00017%, nfe) (gnomAD).

How is Maple syrup urine disease inherited?

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

DBT p.Ser242Ter

c.725C>G · rs201559874 · VCV370744

Pathogenic Multiple submitters

Classification

Pathogenic

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 3 submitters

Consequence

nonsense (stop-gain)

predicted LoF

gnomAD v4.1

Rare

very rare (popmax 0.00017%, nfe)

Conditions

maple syrup urine disease

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	predicted	premature termination codon in exon 6 of 11
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 6.4	GERP 0.94, phastCons 1
Overall
CADD	35.0	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

Grpmax group 0.00017% European (non-Finnish) · 2/1,179,254 alleles

Filtering AF 2.8e-05% ClinGen BA1/BS1 input FAF95, joint · FAF99 1.1e-05%

Overall 0.000124% 2/1,613,066 alleles · very rare

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: DBT
Protein: p.Ser242Ter
Coding: c.725C>G
MANE Select: NM_001918
dbSNP: rs201559874
Type: single nucleotide variant
Location: chr1:100216030 (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 — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Also linked: maple syrup urine disease type 1A

For Maple syrup urine disease (Orphanet):

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

Similar variants

DBT p.Ser242Pro Benign/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.1281+1G>T Pathogenic/Likely pathogenic ★★ same condition
DBT c.51+1G>T Pathogenic/Likely pathogenic ★★ same condition
DBT c.52-1G>A Pathogenic/Likely pathogenic ★★ same condition
DBT p.Arg169Ter Pathogenic/Likely pathogenic ★★ same condition
DBT p.Arg291Ter 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-ser242ter (accessed [today's date]).

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