NM_001918.5:c.670G>T

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 16 ACMG points: 16P and 0B. PVS1PP5_Very_Strong

The NM_001918.5(DBT):c.670G>T(p.Glu224*) variant causes a stop gained change. The variant allele was found at a frequency of 0.0000372 in 1,613,696 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: 𝑓 0.00024 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000016 ( 0 hom. )

Consequence

DBT
NM_001918.5 stop_gained

Scores

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:14

Conservation

PhyloP100: 6.89

Publications

5 publications found

Variant links:

Genes affected

DBT (HGNC:2698): (dihydrolipoamide branched chain transacylase E2) The branched-chain alpha-keto acid dehydrogenase complex (BCKD) is an inner-mitochondrial enzyme complex involved in the breakdown of the branched-chain amino acids isoleucine, leucine, and valine. The BCKD complex is thought to be composed of a core of 24 transacylase (E2) subunits, and associated decarboxylase (E1), dehydrogenase (E3), and regulatory subunits. This gene encodes the transacylase (E2) subunit. Mutations in this gene result in maple syrup urine disease, type 2. Alternatively spliced transcript variants have been described, but their biological validity has not been determined. [provided by RefSeq, Jul 2008]

DBT Gene-Disease associations (from GenCC):

maple syrup urine disease
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), ClinGen
maple syrup urine disease type 2
Inheritance: AR Classification: DEFINITIVE Submitted by: Myriad Women’s Health, G2P
classic maple syrup urine disease
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
intermediate maple syrup urine disease
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
intermittent maple syrup urine disease
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
thiamine-responsive maple syrup urine disease
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

DBT links:

ENSG00000285530 (HGNC:):

ENSG00000285530 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 16 ACMG points.

PVS1

Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.

PP5

Variant 1-100216085-C-A is Pathogenic according to our data. Variant chr1-100216085-C-A is described in ClinVar as Pathogenic. ClinVar VariationId is 94009.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
DBT	NM_001918.5 link	c.670G>T	p.Glu224*	stop_gained	Exon 6 of 11	ENST00000370132.8	NP_001909.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
DBT	ENST00000370132.8 link	c.670G>T	p.Glu224*	stop_gained	Exon 6 of 11	1	NM_001918.5	ENSP00000359151.3

Frequencies

GnomAD3 genomes

AF:

0.000243

AC:

AN:

152106

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.000893

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000636

AC:

AN:

251466

AF XY:

0.0000662

show subpopulations

Gnomad AFR exome

AF:

0.000984

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000157

AC:

AN:

1461472

Hom.:

Cov.:

AF XY:

0.0000179

AC XY:

AN XY:

727060

show subpopulations

African (AFR)

AF:

0.000657

AC:

AN:

33472

American (AMR)

AF:

0.00

AC:

AN:

44722

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26128

East Asian (EAS)

AF:

0.00

AC:

AN:

39672

South Asian (SAS)

AF:

0.00

AC:

AN:

86250

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53414

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5764

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111670

Other (OTH)

AF:

0.0000166

AC:

AN:

60380

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.479

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.000243

AC:

AN:

152224

Hom.:

Cov.:

AF XY:

0.000282

AC XY:

AN XY:

74430

show subpopulations

African (AFR)

AF:

0.000891

AC:

AN:

41542

American (AMR)

AF:

0.00

AC:

AN:

15292

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5188

South Asian (SAS)

AF:

0.00

AC:

AN:

4822

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10596

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

67994

Other (OTH)

AF:

0.00

AC:

AN:

2112

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.514

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.000171

Hom.:

Bravo

AF:

0.000162

ESP6500AA

AF:

0.000454

AC:

ESP6500EA

AF:

0.00

AC:

ExAC

AF:

0.0000906

AC:

Asia WGS

AF:

0.000289

AC:

AN:

3476

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:14

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Maple syrup urine disease

Pathogenic:6

Nov 07, 2021

Genome-Nilou Lab

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Jun 20, 2024

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: DBT c.670G>T (p.Glu224X) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. The variant allele was found at a frequency of 6.4e-05 in 251466 control chromosomes. c.670G>T has been reported in the literature in multiple homozygous and compound heterozygous individuals affected with Maple Syrup Urine Disease (e.g., Fisher_1993). These data indicate that the variant is very likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication has been ascertained in the context of this evaluation (PMID: 8430702). ClinVar contains an entry for this variant (Variation ID: 94009). Based on the evidence outlined above, the variant was classified as pathogenic. -

Oct 11, 2019

Revvity Omics, Revvity

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Nov 05, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change creates a premature translational stop signal (p.Glu224*) in the DBT gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in DBT are known to be pathogenic (PMID: 16579849, 16786533). This variant is present in population databases (rs74103423, gnomAD 0.1%). This premature translational stop signal has been observed in individuals with maple syrup urine disease (PMID: 8430702). ClinVar contains an entry for this variant (Variation ID: 94009). For these reasons, this variant has been classified as Pathogenic. -

Oct 31, 2018

Fulgent Genetics, Fulgent Genetics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Jan 29, 2024

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The p.Glu224X variant (also described as p.Glu163X as a legacy nomenclature) in DBT has been reported in at least 6 individuals in the homozygous or compound heterozygous state with maple syrup urine disease (MSUD), where BCKD enzyme activity was markedly reduced in at least 3 individuals (Fisher 1993 PMID: 8430702, Khalifa 2020 PMID: 32812330). This variant has also been reported by other clinical laboratories in ClinVar (Variation ID 94009) and has been identified in 0.09% (37/41420) of African chromosomes by gnomAD (http://gnomad.broadinstitute.org, v.3.1.2). This nonsense variant leads to a premature termination codon at position 43, which is predicted to lead to a truncated or absent protein. This is corroborated by in vitro functional studies that show a truncated protein in patients with MSUD compared with full-length wildtype (Fisher 1993 PMID: 8430702). Biallelic loss of function of the DBT gene is an established disease mechanism in autosomal recessive MSUD. In summary, this variant meets criteria to be classified as pathogenic for autosomal recessive MSUD. ACMG/AMP Criteria applied: PVS1_Moderate, PM3, PS3_Supporting, PP4. -

Maple syrup urine disease type 2

Pathogenic:3

Nov 03, 2022

DASA

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The c.670G>T;p.(Glu224*) variant creates a premature translational stop signal in the DBT gene. It is expected to result in an absent or disrupted protein product - PVS1. This sequence change has been observed in affected individual(s) and ClinVar contains an entry for this variant (ClinVar ID: 94009; PMID: 32812330) - PS4. The variant is present at low allele frequencies population databases (rs74103423 – gnomAD 0.0009193%; ABraOM 0.000427 frequency - https://abraom.ib.usp.br/) - PM2_supporting. In summary, the currently available evidence indicates that the variant is pathogenic. -

Jun 28, 2025

Immunogenetics and Transplant Biology Service, University Hospital "Città della Salute e della Scienza di Torino"

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Apr 08, 2024

Fulgent Genetics, Fulgent Genetics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Maple syrup urine disease type 1A

Pathogenic:3

Mar 27, 2024

Baylor Genetics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Nov 03, 2016

Counsyl

Significance:Likely pathogenic

Review Status:no assertion criteria provided

Collection Method:clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -

Jul 31, 2023

3billion

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The variant is observed at an extremely low frequency in the gnomAD v2.1.1 dataset (total allele frequency: 0.009%). Predicted Consequence/Location: Stop-gained (nonsense): predicted to result in a loss or disruption of normal protein function through nonsense-mediated decay (NMD) or protein truncation. Multiple pathogenic variants are reported downstream of the variant. The variant has been reported at least twice as pathogenic with clinical assertions and evidence for the classification (ClinVar ID: VCV000094009 /PMID: 8430702). Therefore, this variant is classified as Pathogenic according to the recommendation of ACMG/AMP guideline. -

not provided

Pathogenic:2

Aug 23, 2013

Eurofins Ntd Llc (ga)

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

May 23, 2023

GeneDx

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Functional studies demonstrate that cell lines with the E224X variant result in a markedly truncated polypeptide compared with full-length wildtype (Fisher et al., 1993); Nonsense variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss-of-function is a known mechanism of disease; This variant is associated with the following publications: (PMID: 8430702, 25087612, 25525159, 31980395, 32812330, 31589614, 31345219) -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.34

BayesDel_noAF

Pathogenic

0.65

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

Eigen

Pathogenic

0.85

Eigen_PC

Pathogenic

0.71

FATHMM_MKL

Pathogenic

0.98

PhyloP100

6.9

Vest4

0.94

GERP RS

4.8

Mutation Taster

=3/197

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.0

Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over