rs398123671

Variant names:

• chr1-100216178-C-T
• rs398123671
• NM_001918.5:c.577G>A

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_001918.5(DBT):​c.577G>A​(p.Gly193Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000685 in 1,460,786 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 Uncertain significance (★★). Synonymous variant affecting the same amino acid position (i.e. G193G) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: DBT NM_001918.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 7.41
• Publications: 2 publications found

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

ENSG00000285530 (HGNC:):

ACMG classification

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.88

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
DBT	NM_001918.5	c.577G>A	p.Gly193Ser	missense_variant	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	c.577G>A	p.Gly193Ser	missense_variant	Exon 6 of 11	1	NM_001918.5	ENSP00000359151.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1460786 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 726768

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33458

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26128

East Asian (EAS) AF: 0.00 AC: 0 AN: 39676

South Asian (SAS) AF: 0.00 AC: 0 AN: 86226

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53354

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5744

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111138

Other (OTH) AF: 0.0000166 AC: 1 AN: 60338

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Maple syrup urine disease Uncertain:2

Sep 16, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glycine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 193 of the DBT protein (p.Gly193Ser). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with clinical features of DBT-related conditions (internal data). ClinVar contains an entry for this variant (Variation ID: 94006). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is expected to disrupt DBT protein function with a positive predictive value of 95%. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Nov 07, 2021

Genome-Nilou Lab

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Uncertain:1

Sep 04, 2013

Eurofins Ntd Llc (ga)

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.43
BayesDel_addAF	Pathogenic	0.35	D
BayesDel_noAF	Pathogenic	0.26
CADD	Pathogenic	28
DANN	Uncertain	1.0
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.98
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.87	.;D
M_CAP	Benign	0.031	D
MetaRNN	Pathogenic	0.88	D;D
MetaSVM	Uncertain	0.27	D
PhyloP100		7.4
PrimateAI	Uncertain	0.75	T
PROVEAN	Uncertain	-3.1	D;D
REVEL	Uncertain	0.54
Sift	Benign	0.071	T;T
Sift4G	Uncertain	0.039	D;T
Vest4		0.89
MutPred		0.73		Loss of catalytic residue at G193 (P = 0.0187);Loss of catalytic residue at G193 (P = 0.0187);
MVP		0.92
MPC		0.96
ClinPred		1.0	D
GERP RS		5.9
gMVP		0.87
Mutation Taster		=28/72	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs398123671; hg19: chr1-100681734;