19-41419156-AC-A

Position:

• chr19-41419156-AC-A

Variant summary

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

The NM_000709.4(BCKDHA):​c.511del​(p.Leu171TrpfsTer159) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,876 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: BCKDHA NM_000709.4 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 0.769

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: 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 19-41419156-AC-A is Pathogenic according to our data. Variant chr19-41419156-AC-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 517592.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
BCKDHA	NM_000709.4	c.511del	p.Leu171TrpfsTer159	frameshift_variant	5/9	ENST00000269980.7	NP_000700.1
BCKDHA	NM_001164783.2	c.511del	p.Leu171TrpfsTer158	frameshift_variant	5/9		NP_001158255.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
BCKDHA	ENST00000269980.7	c.511del	p.Leu171TrpfsTer159	frameshift_variant	5/9	1	NM_000709.4	ENSP00000269980	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.0000159 AC: 4 AN: 251466 Hom.: 0 AF XY: 0.0000221 AC XY: 3 AN XY: 135920

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 SAS exome AF: 0.0000980

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000163

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461876 Hom.: 0 Cov.: 31 AF XY: 0.00000413 AC XY: 3 AN XY: 727242

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000348

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.0000416

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Maple syrup urine disease Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Nov 07, 2021	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Oct 05, 2017	The p.Leu171TrpfsX159 (NM_000709.3 c.511delC) variant in BCKDHA has not been pre viously reported in individuals with maple syrup urine disease. It has been iden tified in 3/30782 South Asian chromosomes by the Genome Aggregation Database (ht tp://gnomad.broadinstitute.org; rs762084007). This variant is predicted to cause a frameshift, which alters the protein?s amino acid sequence beginning at posit ion 171 and leads to a premature termination codon 159 amino acids downstream. T his alteration is then predicted to lead to a truncated or absent protein. Biall elic loss of function of the BCKDHA gene is associated with maple syrup urine di sease. In summary, although additional studies are required to fully establish a null impact, the p.Leu171TrpfsX159 variant is likely pathogenic for maple syrup urine disease in an autosomal recessive manner based on its predicted impact on the protein. ACMG/AMP Criteria applied: PVS1; PM2 (Richards 2015). -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Oct 26, 2023	This sequence change creates a premature translational stop signal (p.Leu171Trpfs*159) in the BCKDHA gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in BCKDHA are known to be pathogenic (PMID: 16786533, 22593002). This variant is present in population databases (rs762084007, gnomAD 0.01%). This premature translational stop signal has been observed in individual(s) with maple syrup urine disease (PMID: 31980395). ClinVar contains an entry for this variant (Variation ID: 517592). For these reasons, this variant has been classified as Pathogenic. -

Maple syrup urine disease type 1A Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Baylor Genetics

Jan 01, 2024

- -

Computational scores

Source: dbNSFP v4.3

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: rs762084007; hg19: chr19-41925061;