rs398123496

chr19-41410817-G-A

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1_Strong PM2 PP3_Strong PP5_Very_Strong

The NM_000709.4(BCKDHA):c.288+1G>A variant causes a splice donor change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000752 in 1,461,860 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 2/2 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000075 (0 hom.)
• Consequence: BCKDHA NM_000709.4 splice_donor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:10
• Conservation: PhyloP100: 9.26

Genes affected

BCKDHA (HGNC:986): (branched chain keto acid dehydrogenase E1 subunit alpha) The branched-chain alpha-keto acid (BCAA) dehydrogenase (BCKD) complex is an innter mitochondrial enzyme complex that catalyzes the second major step in the catabolism of the branched-chain amino acids leucine, isoleucine, and valine. The BCKD complex consists of three catalytic components: a heterotetrameric (alpha2-beta2) branched-chain alpha-keto acid decarboxylase (E1), a dihydrolipoyl transacylase (E2), and a dihydrolipoamide dehydrogenase (E3). This gene encodes the alpha subunit of the decarboxylase (E1) component. Mutations in this gene result in maple syrup urine disease, type IA. Multiple transcript variants encoding different isoforms have been found for this gene.[provided by RefSeq, Sep 2009]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Splicing variant, NOT destroyed by nmd, known LOF gene, truncates exone, which is 0.13378176 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 19-41410817-G-A is Pathogenic according to our data. Variant chr19-41410817-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 93351.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
BCKDHA	NM_000709.4	c.288+1G>A		splice_donor_variant		ENST00000269980.7
BCKDHA	NM_001164783.2	c.288+1G>A		splice_donor_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BCKDHA	ENST00000269980.7	c.288+1G>A		splice_donor_variant		1	NM_000709.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.0000159 AC: 4 AN: 251274 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135846

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000578

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: 0.00000880

Gnomad OTH exome AF: 0.000163

GnomAD4 exome AF: 0.00000752 AC: 11 AN: 1461860 Hom.: 0 Cov.: 33 AF XY: 0.00000413 AC XY: 3 AN XY: 727238

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.000134

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: 0.00000270

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

Bravo AF: 0.0000227

ExAC AF: 0.00000824 AC: 1

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:10

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Maple syrup urine disease Pathogenic:6

Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Oct 24, 2023	- -
Pathogenic, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	Nov 10, 2021	NM_000709.3(BCKDHA):c.288+1G>A is a canonical splice variant classified as pathogenic in the context of maple syrup urine disease type Ia. c.288+1G>A has been observed in cases with relevant disease (PMID: 31980395, 31119508). Functional assessments of this variant are not available in the literature. c.288+1G>A has been observed in population frequency databases (gnomAD: OTH 0.02%). In summary, NM_000709.3(BCKDHA):c.288+1G>A is a canonical splice variant that has been observed more frequently in cases with the relevant disease than in healthy populations. Please note: this variant was assessed in the context of healthy population screening. -
Pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Feb 18, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Nov 07, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Oct 19, 2023	This sequence change affects a donor splice site in intron 2 of the BCKDHA gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in BCKDHA are known to be pathogenic (PMID: 16786533, 22593002). This variant is present in population databases (rs398123496, gnomAD 0.006%). Disruption of this splice site has been observed in individual(s) with maple syrup urine disease (PMID: 26901124). ClinVar contains an entry for this variant (Variation ID: 93351). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. 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 variant is located within the ±2 bp from a splice site in the BCKDHA gene, where loss of function is a known mechanism of disease. It is present in population databases in low frequency (GnomAD exomes: 0.000016, ExAC: A=0.000008). This variant has been published in the literature associated with individuals with MSUD (PMID: 26901124, PMID: 31119508). It was found in a compound heterozygous state with a pathogenic variant in a patient with MSUD phenotype. -

Maple syrup urine disease type 1A Pathogenic:2

Pathogenic, no assertion criteria provided	clinical testing	Natera, Inc.	Sep 16, 2020	- -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Mar 19, 2021	Variant summary: BCKDHA c.288+1G>A is located in a canonical splice-site and is predicted to affect mRNA splicing resulting in a significantly altered protein due to either exon skipping, shortening, or inclusion of intronic material. Several computational tools predict a significant impact on normal splicing: Four predict the variant abolishes a 5 splicing donor site. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 1.6e-05 in 251274 control chromosomes (gnomAD). c.288+1G>A has been reported in the literature in at least a homozygous individual affected with Maple Syrup Urine Disease (example: Abiri_BCKDHA_MutatRes_2016, Strauss_BCKDHA_MGM_2020). These data indicate that the variant is likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Four ClinVar submitters (evaluation after 2014) cite the variant as likely pathogenic/pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

not provided Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Aug 23, 2013	- -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Oct 23, 2015	The c.288+1 G>A splice site mutation in the BCKDHA gene destroys the canonical splice donor site in intron 2. It is predicted to cause abnormal gene splicing, either leading to an abnormal message that is subject to nonsense-mediated mRNA decay, or to an abnormal protein product if the message is used for protein translation. The variant is found in BCKDHA panel(s). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.34	D
BayesDel_noAF	Pathogenic	0.42
Cadd	Pathogenic	33
Dann	Uncertain	0.99
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	1.0	D
MutationTaster	Benign	1.0	D;D
GERP RS		5.4
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.95
SpliceAI score (max)		0.97		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.97		Position offset: -1

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

Publications

LitVar

Other links and lift over

dbSNP: rs398123496; hg19: chr19-41916722;