chr6-80273189-G-A

Position:

• chr6-80273189-G-A

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PM2 PP3_Strong PP5_Very_Strong

The NM_183050.4(BCKDHB):​c.1006G>A​(p.Gly336Ser) variant causes a missense change. The variant allele was found at a frequency of 0.00000274 in 1,461,324 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 (★★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: BCKDHB NM_183050.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:8
• Conservation: PhyloP100: 6.27

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]

ACMG classification

Verdict is Pathogenic. Variant got 14 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.991
• PP5: Variant 6-80273189-G-A is Pathogenic according to our data. Variant chr6-80273189-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 96562.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
BCKDHB	NM_183050.4	c.1006G>A	p.Gly336Ser	missense_variant	9/10	ENST00000320393.9	NP_898871.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
BCKDHB	ENST00000320393.9	c.1006G>A	p.Gly336Ser	missense_variant	9/10	1	NM_183050.4	ENSP00000318351	P1
BCKDHB	ENST00000356489.9	c.1006G>A	p.Gly336Ser	missense_variant	9/11	1		ENSP00000348880	P1
BCKDHB	ENST00000468520.1	n.236G>A		non_coding_transcript_exon_variant	3/3	5

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 250950 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135616

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad SAS 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: 0.00000274 AC: 4 AN: 1461324 Hom.: 0 Cov.: 30 AF XY: 0.00000275 AC XY: 2 AN XY: 726954

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000252

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 9.00e-7

Gnomad4 OTH exome AF: 0.0000331

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:8

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Maple syrup urine disease Pathogenic:4

Likely pathogenic, criteria provided, single submitter	clinical testing	Mendelics	May 28, 2019	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Nov 07, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Dec 01, 2023	This sequence change replaces glycine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 336 of the BCKDHB protein (p.Gly336Ser). This variant is present in population databases (rs398124560, gnomAD 0.006%). This missense change has been observed in individual(s) with maple syrup urine disease (PMID: 28417071, 28830848, 31112740). ClinVar contains an entry for this variant (Variation ID: 96562). 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%. For these reasons, this variant has been classified as Pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	May 16, 2018	- -

Maple syrup urine disease type 1B Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Jul 05, 2023	Variant summary: BCKDHB c.1006G>A (p.Gly336Ser) results in a non-conservative amino acid change located in the C-terminal domain (IPR033248) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 4e-06 in 251350 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.1006G>A has been reported in the literature in multiple homozygous and compound heterozygous individuals affected with Maple Syrup Urine Disease Type 1B (e.g., Imtiaz_2017, Cheng_2017). These data indicate that the variant is very likely to be associated with disease. The following publications have been ascertained in the context of this evaluation (PMID: 28830848, 28417071). Five submitters have reported clinical-significance assessments for this variant to ClinVar after 2014. All submitters classified the variant as pathogenic (n = 1) or likely pathogenic (n = 4). Based on the evidence outlined above, the variant was classified as pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center	Mar 25, 2024	- -

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Eurofins Ntd Llc (ga)

Dec 07, 2017

- -

Maple syrup urine disease type 1A Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Baylor Genetics

Mar 10, 2024

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.31
BayesDel_addAF	Pathogenic	0.37	D
BayesDel_noAF	Pathogenic	0.46
CADD	Pathogenic	32
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.78	D;D
Eigen	Pathogenic	0.69
Eigen_PC	Uncertain	0.63
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	.;D
M_CAP	Pathogenic	0.53	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Benign	1.7	L;L
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.66	T
PROVEAN	Pathogenic	-5.7	D;D
REVEL	Pathogenic	0.92
Sift	Uncertain	0.026	D;D
Sift4G	Uncertain	0.050	T;T
Polyphen		1.0	D;D
Vest4		0.97
MutPred		0.89		Gain of disorder (P = 0.0685);Gain of disorder (P = 0.0685);
MVP		0.99
MPC		0.77
ClinPred		0.99	D
GERP RS		5.5
Varity_R		0.88
gMVP		0.93

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

LitVar

Other links and lift over

dbSNP: rs398124560; hg19: chr6-80982906;