6-80273199-C-T

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 17 ACMG points: 17P and 0B. PM1PM2PP2PP3_StrongPP5_Very_Strong

The NM_183050.4(BCKDHB):c.1016C>T(p.Ser339Leu) variant causes a missense change. The variant allele was found at a frequency of 0.0000155 in 1,613,312 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 Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. S339S) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000020 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000015 ( 0 hom. )

Consequence

BCKDHB
NM_183050.4 missense

Scores

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:11

Conservation

PhyloP100: 4.76

Publications

6 publications found

Variant links:

Genes affected

BCKDHB (HGNC:987): (branched chain keto acid dehydrogenase E1 subunit beta) This gene encodes the E1 beta subunit of branched-chain keto acid dehydrogenase, which is a multienzyme complex associated with the inner membrane of mitochondria. This enzyme complex functions in the catabolism of branched-chain amino acids. Mutations in this gene have been associated with maple syrup urine disease (MSUD), type 1B, a disease characterized by a maple syrup odor to the urine in addition to mental and physical retardation and feeding problems. Alternative splicing at this locus results in multiple transcript variants. [provided by RefSeq, Jan 2016]

BCKDHB Gene-Disease associations (from GenCC):

maple syrup urine disease type 1B
Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen, G2P, Myriad Women’s Health
maple syrup urine disease
Inheritance: AR Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
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

BCKDHB links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 17 ACMG points.

PM1

In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 5 uncertain in NM_183050.4

PM2

Very rare variant in population databases, with high coverage;

PP2

Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 51 curated pathogenic missense variants (we use a threshold of 10). The gene has 5 curated benign missense variants. Gene score misZ: -0.17637 (below the threshold of 3.09). Trascript score misZ: -0.0026186 (below the threshold of 3.09). GenCC associations: The gene is linked to classic maple syrup urine disease, thiamine-responsive maple syrup urine disease, intermittent maple syrup urine disease, intermediate maple syrup urine disease, maple syrup urine disease type 1B, maple syrup urine disease.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.976

PP5

Variant 6-80273199-C-T is Pathogenic according to our data. Variant chr6-80273199-C-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 96563.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
BCKDHB	NM_183050.4 link	c.1016C>T	p.Ser339Leu	missense_variant	Exon 9 of 10	ENST00000320393.9	NP_898871.1	P21953-1A0A140VKB3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
BCKDHB	ENST00000320393.9 link	c.1016C>T	p.Ser339Leu	missense_variant	Exon 9 of 10	1	NM_183050.4	ENSP00000318351.5	P21953-1
BCKDHB	ENST00000356489.9 link	c.1016C>T	p.Ser339Leu	missense_variant	Exon 9 of 11	1		ENSP00000348880.5	P21953-1
BCKDHB	ENST00000468520.1 link	n.*9C>T		downstream_gene_variant		5

Frequencies

GnomAD3 genomes

AF:

0.0000197

AC:

AN:

152102

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000655

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.000193

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00

AC:

AN:

250844

AF XY:

0.00

Gnomad AFR exome

AF:

0.00

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:

0.0000151

AC:

AN:

1461210

Hom.:

Cov.:

AF XY:

0.0000138

AC XY:

AN XY:

726900

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33458

American (AMR)

AF:

0.00

AC:

AN:

44654

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26102

East Asian (EAS)

AF:

0.00

AC:

AN:

39658

South Asian (SAS)

AF:

0.0000232

AC:

AN:

86246

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53390

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5762

European-Non Finnish (NFE)

AF:

0.0000135

AC:

AN:

1111592

Other (OTH)

AF:

0.0000829

AC:

AN:

60348

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.455

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:

0.0000197

AC:

AN:

152102

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74288

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41414

American (AMR)

AF:

0.0000655

AC:

AN:

15260

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3468

East Asian (EAS)

AF:

0.000193

AC:

AN:

5192

South Asian (SAS)

AF:

0.00

AC:

AN:

4828

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10600

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000147

AC:

AN:

68018

Other (OTH)

AF:

0.00

AC:

AN:

2094

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.492

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:

0.000541

Hom.:

Bravo

AF:

0.0000189

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:11

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Maple syrup urine disease

Pathogenic:5

Lifecell International Pvt. Ltd

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

A Heterozygous Missense variant c.1016C>T in Exon 9 of the BCKDHB gene that results in the amino acid substitution p.Ser339Leu was identified. The observed variant has a minor allele frequency of 0.00003 in and genomes and is novel in gnomAD exomes. The severity of the impact of this variant on the protein is medium, based on the effect of the protein and REVEL score. Rare Exome Variant Ensemble Learner (REVEL) is an ensembl method for predicting the pathogenicity of missense variants based on a combination of scores from 13individual tools: MutPred, FATHMM v2.3, VEST 3.0, PolyPhen-2, SIFT, PROVEAN, MutationAssessor, MutationTaster, LRT, GERP++, SiPhy, phyloP, and phastCons. The REVEL score for an individual missense variant can range from 0 to 1, with higher scores reflecting greater likelihood that the variant is disease-causing. ClinVar has also classified this variant as Pathogenic [Variant ID: 96563]. This variant has previously been reported for maple syrup urine disease by Ali, Ernie Zuraida, and Lock-Hock Ngu., 2018. Experimental studies have shown that this missense change affects BCKDHB function by Wynn, R. Max, et al., 2001. For these reasons this variant has been classified as Likely Pathogenic. -

Feb 08, 2023

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

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: BCKDHB c.1016C>T (p.Ser339Leu) results in a non-conservative amino acid change located in the Transketolase, C-terminal domain (IPR033248) of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 250844 control chromosomes (gnomAD). c.1016C>T has been reported in the literature in multiple individuals affected with Maple Syrup Urine Disease (e.g. Wynn_2001, Gorzelany_2009, Bashyam_2012). These data indicate that the variant is very likely to be associated with disease. At least one publication reported experimental evidence evaluating an impact on protein function, and demonstrated complete absence of activity in patient derived fibroblasts, and in a bacterial expression system (Wynn_2001). Three clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014, partly without evidence for independent evaluation, and classified the variant as pathogenic (n=2) or likely pathogenic (n=1). Based on the evidence outlined above, the variant was classified as pathogenic. -

Nov 29, 2021

Revvity Omics, Revvity

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Nov 07, 2021

Genome-Nilou Lab

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Feb 29, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces serine, which is neutral and polar, with leucine, which is neutral and non-polar, at codon 339 of the BCKDHB protein (p.Ser339Leu). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This missense change has been observed in individual(s) with BCKDHB-related conditions (PMID: 11448970, 22593002, 30228974; Invitae). This variant is also known as p.Ser289Leu. ClinVar contains an entry for this variant (Variation ID: 96563). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt BCKDHB protein function with a negative predictive value of 80%. Experimental studies have shown that this missense change affects BCKDHB function (PMID: 11448970). For these reasons, this variant has been classified as Pathogenic. -

Maple syrup urine disease type 1B

Pathogenic:4

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

- -

Mar 26, 2024

Fulgent Genetics, Fulgent Genetics

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

May 11, 2023

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:research

- -

Feb 01, 2024

Laboratory of Medical Genetics, National & Kapodistrian University of Athens

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:curation

- -

not provided

Pathogenic:1

Apr 22, 2015

Eurofins Ntd Llc (ga)

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Maple syrup urine disease type 1A

Pathogenic:1

Mar 05, 2024

Baylor Genetics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.52

BayesDel_addAF

Pathogenic

0.49

BayesDel_noAF

Pathogenic

0.47

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

DEOGEN2

Pathogenic

0.87

D;D

Eigen

Uncertain

0.52

Eigen_PC

Uncertain

0.43

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Pathogenic

0.99

.;D

M_CAP

Pathogenic

0.45

MetaRNN

Pathogenic

0.98

D;D

MetaSVM

Pathogenic

0.85

MutationAssessor

Uncertain

2.8

M;M

PhyloP100

4.8

PrimateAI

Uncertain

0.73

PROVEAN

Uncertain

-3.0

D;D

REVEL

Pathogenic

0.79

Sift

Uncertain

0.0010

D;D

Sift4G

Uncertain

0.015

D;D

Polyphen

0.99

D;D

Vest4

0.97

MutPred

0.86

Loss of disorder (P = 0.0059);Loss of disorder (P = 0.0059);

MVP

0.99

MPC

0.35

ClinPred

0.96

GERP RS

5.7

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.90

gMVP

0.88

Mutation Taster

=3/97

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

Splicevardb

2.0

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