rs774306610

Positions:

• chr6-80168961-T-A

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_183050.4(BCKDHB):​c.564T>A​(p.Cys188Ter) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000248 in 1,614,070 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 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: BCKDHB NM_183050.4 stop_gained
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 0.732

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 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 6-80168961-T-A is Pathogenic according to our data. Variant chr6-80168961-T-A is described in ClinVar as [Pathogenic]. Clinvar id is 580585.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
BCKDHB	NM_183050.4	c.564T>A	p.Cys188Ter	stop_gained	5/10	ENST00000320393.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BCKDHB	ENST00000320393.9	c.564T>A	p.Cys188Ter	stop_gained	5/10	1	NM_183050.4	P1
BCKDHB	ENST00000356489.9	c.564T>A	p.Cys188Ter	stop_gained	5/11	1		P1
BCKDHB	ENST00000369760.8	c.564T>A	p.Cys188Ter	stop_gained	5/6	3

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152216 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000655

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

GnomAD3 exomes AF: 0.0000119 AC: 3 AN: 251402 Hom.: 0 AF XY: 0.0000147 AC XY: 2 AN XY: 135876

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000867

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

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: 0.00000205 AC: 3 AN: 1461854 Hom.: 0 Cov.: 34 AF XY: 0.00000275 AC XY: 2 AN XY: 727236

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000671

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152216 Hom.: 0 Cov.: 32 AF XY: 0.0000134 AC XY: 1 AN XY: 74364

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.0000655

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000378

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Maple syrup urine disease Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Dec 12, 2023	This sequence change creates a premature translational stop signal (p.Cys188*) in the BCKDHB gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in BCKDHB are known to be pathogenic (PMID: 16786533, 22593002). This variant is present in population databases (rs774306610, gnomAD 0.009%). This premature translational stop signal has been observed in individual(s) with maple syrup urine disease (PMID: 19480318). ClinVar contains an entry for this variant (Variation ID: 580585). For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	National Newborn Screening Laboratory, Hospital Nacional de Niños	-	This is a null variant in a gene where the loss of function is a known disease mechanism, resulting in a truncated protein creating a premature stop codon. It is present in population databases in low frequency (gnomAD exomes: 0,00001; ExAC: 0,000008). This variant has been published in the literature associated with individuals with MSUD (PMID: 19480318). -

Maple syrup urine disease type 1B Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

Natera, Inc.

Nov 30, 2020

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.49	D
BayesDel_noAF	Pathogenic	0.59
CADD	Pathogenic	36
DANN	Uncertain	0.99
Eigen	Pathogenic	0.73
Eigen_PC	Uncertain	0.55
FATHMM_MKL	Uncertain	0.86	D
MutationTaster	Benign	1.0	A;A;A;A
Vest4		0.90
GERP RS		3.9

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

Publications

LitVar

Other links and lift over

dbSNP: rs774306610; hg19: chr6-80878678;