rs137852870

Positions:

• chr19-41424582-T-A
• chr19-41424582-T-C

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_000709.4(BCKDHA):​c.1312T>A​(p.Tyr438Asn) variant causes a missense change. The variant allele was found at a frequency of 0.0000571 in 1,611,804 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. Y438H) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: 𝑓 0.00012 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000051 (0 hom.)
• Consequence: BCKDHA NM_000709.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:18 O:1
• Conservation: PhyloP100: 5.59

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 16 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr19-41424582-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1344509.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.981
• PP5: Variant 19-41424582-T-A is Pathogenic according to our data. Variant chr19-41424582-T-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 100009.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr19-41424582-T-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
BCKDHA	NM_000709.4	c.1312T>A	p.Tyr438Asn	missense_variant	9/9	ENST00000269980.7
BCKDHA	NM_001164783.2	c.1309T>A	p.Tyr437Asn	missense_variant	9/9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BCKDHA	ENST00000269980.7	c.1312T>A	p.Tyr438Asn	missense_variant	9/9	1	NM_000709.4	P1
BCKDHA	ENST00000457836.6	c.1321T>A	p.Tyr441Asn	missense_variant	9/9	2
BCKDHA	ENST00000544905.1	c.144T>A	p.Thr48=	synonymous_variant	2/2	2

Frequencies

GnomAD3 genomes AF: 0.000118 AC: 18 AN: 152154 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

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: 0.000265

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000643 AC: 16 AN: 248834 Hom.: 0 AF XY: 0.0000521 AC XY: 7 AN XY: 134482

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: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000143

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000507 AC: 74 AN: 1459650 Hom.: 0 Cov.: 35 AF XY: 0.0000524 AC XY: 38 AN XY: 725838

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.0000375

Gnomad4 NFE exome AF: 0.0000612

Gnomad4 OTH exome AF: 0.0000498

GnomAD4 genome AF: 0.000118 AC: 18 AN: 152154 Hom.: 0 Cov.: 32 AF XY: 0.000135 AC XY: 10 AN XY: 74312

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000265

Gnomad4 OTH AF: 0.00

Alfa AF: 0.000142 Hom.: 0

Bravo AF: 0.0000831

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000233 AC: 2

ExAC AF: 0.0000494 AC: 6

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:18 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Maple syrup urine disease Pathogenic:10 Other:1

Pathogenic, criteria provided, single submitter	clinical testing	Neuberg Centre For Genomic Medicine, NCGM	-	The missense variant c.1312T>A (p.Tyr438Asn) in BCKDHA gene has been observed in individual(s) with maple syrup urine disease (Latisha D Love-Gregory et.al.,2002). Experimental studies have shown that this missense change affects BCKDHA function (Stojiljkovic M et.al 2016). This variant has been reported to the ClinVar database as Pathogenic/Likely_pathogenic. The p.Tyr438Asn variant is reported with allele frequency 0.007% in gnomAD exomes and novel in 1000 Genomes. The amino acid Tyr at position 438 is changed to a Asn changing protein sequence and it might alter its composition and physico-chemical properties. For these reasons, this variant has been classified as Pathogenic . -
Likely pathogenic, criteria provided, single submitter	clinical testing	Centre for Mendelian Genomics, University Medical Centre Ljubljana	Jan 16, 2020	This variant was classified as: Likely pathogenic. The following ACMG criteria were applied in classifying this variant: PS1,PS3,PM2,PP3. -
Pathogenic, no assertion criteria provided	literature only	OMIM	Aug 15, 2003	- -
Pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Nov 07, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Oct 31, 2018	- -
Likely pathogenic, criteria provided, single submitter	curation	SIB Swiss Institute of Bioinformatics	May 31, 2018	This variant is interpreted as a Likely Pathogenic, for Maple syrup urine disease, in Autosomal Recessive manner. The following ACMG Tag(s) were applied: PM2 => Absent from controls (or at extremely low frequency if recessive) in Exome Sequencing Project, 1000 Genomes Project, or Exome Aggregation Consortium. PP3 => Multiple lines of computational evidence support a deleterious effect on the gene or gene product. PS3 => Well-established functional studies show a deleterious effect (PMID:1885764). -
Pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Sep 22, 2021	- -
Likely pathogenic, no assertion criteria provided	clinical testing	Counsyl	Jan 24, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Dec 23, 2023	This sequence change replaces tyrosine, which is neutral and polar, with asparagine, which is neutral and polar, at codon 438 of the BCKDHA protein (p.Tyr438Asn). This variant is present in population databases (rs137852870, gnomAD 0.02%). This missense change has been observed in individual(s) with maple syrup urine disease (PMID: 2703538, 11825067, 12888983, 20136525, 26830710, 28170084). It has also been observed to segregate with disease in related individuals. This variant is also known as Y393N. ClinVar contains an entry for this variant (Variation ID: 100009). 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 expected to disrupt BCKDHA protein function with a positive predictive value of 95%. Experimental studies have shown that this missense change affects BCKDHA function (PMID: 1885764). For these reasons, this variant has been classified as Pathogenic. -
not provided, no classification provided	literature only	GeneReviews	-	- -
Pathogenic, criteria provided, single submitter	research	UNC Molecular Genetics Laboratory, University of North Carolina at Chapel Hill	-	The BCKDHA c.1312T>A (p.Y438N) variant (also called Y393N) is a pathogenic founder variant associated with maple syrup urine disease (MSUD) in the Old Order Mennonite population. The p.Y438N variant has been associated with classical MSUD in a homozygous state, and in non-Mennonite individuals in a compound heterozygous state. This variant has been shown to destabilize the E1 catalytic subunit of the branched-chain alpha-keto acid dehydrogenase complex and was associated with very low enzyme activity (PMID: 1885764; 2241958; 2703538; 11825067; 26830710). -

Maple syrup urine disease type 1A Pathogenic:4

Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Mar 30, 2024	- -
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	Jan 06, 2017	Variant summary: The BCKDHA c.1312T>A (p.Tyr438Asn) variant involves the alteration of a conserved nucleotide. 5/5 in silico tools predict a damaging outcome for this substitution. This variant was found in 6/119260 control chromosomes at a frequency of 0.0000503, which does not exceed the estimated maximal expected allele frequency of a pathogenic BCKDHA variant (0.0016771). It was reported in several MSUD patients in either homozygosity or in compound heterozygosity with other disease causing variants indicating pathogenicity. Moreover, the c.1312T>A is considered to be a founder mutation in certain Mennonite populations (GeneReviews). In addition, multiple clinical diagnostic laboratories/reputable databases classified this variant as pathogenic. Taken together, this variant is classified as pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Genetic Services Laboratory, University of Chicago	Oct 05, 2015	- -

not provided Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Center for Pediatric Genomic Medicine, Children's Mercy Hospital and Clinics	Jul 05, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Aug 13, 2012	- -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Mar 31, 2023	Published functional studies found this variant is associated with significantly reduced enzyme activity (Fisher CR et al., 1991); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Also known as p.(Y393N); This variant is associated with the following publications: (PMID: 14517957, 26830710, 11825067, 24268812, 21228398, 25087612, 19456321, 19715473, 11486905, 18378174, 21844576, 12888983, 7707687, 16468966, 2703538, 28170084, 31028937, 31589614, 32853555, 25255367, 22593002, 33996492, 32812330, 31980395, 1867199, 2241958, 1885764) -

Inborn genetic diseases Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Aug 25, 2021

The c.1312T>A (p.Y438N) alteration is located in exon 9 (coding exon 9) of the BCKDHA gene. This alteration results from a T to A substitution at nucleotide position 1312, causing the tyrosine (Y) at amino acid position 438 to be replaced by an asparagine (N). Based on data from gnomAD, the A allele has an overall frequency of 0.01% (21/280202) total alleles studied. The highest observed frequency was 0.02% (21/127306) of European (non-Finnish) alleles. This mutation, also referred to as Y393N in the literature, has been reported in the homozygous state in several patients with maple syrup urine disease and is a founder mutation with an estimated carrier frequency of approximately 8% in the Old Order Mennonite population (Fisher, 1991a; Puffenberger, 2003; Khalifa, 2020). In vitro functional studies demonstrated that this mutation impedes assembly of the E1α and E1β subunits (Fisher, 1991b). This alteration is predicted to be deleterious by in silico analysis. Based on the available evidence, this alteration is classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.97
BayesDel_addAF	Pathogenic	0.36	D
BayesDel_noAF	Pathogenic	0.53
CADD	Pathogenic	27
DANN	Uncertain	0.99
Eigen	Pathogenic	0.75
Eigen_PC	Uncertain	0.66
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.95	D;D;D
M_CAP	Pathogenic	0.91	D
MetaRNN	Pathogenic	0.98	D;D;D
MetaSVM	Pathogenic	1.0	D
MutationTaster	Benign	1.0	A;A
PrimateAI	Uncertain	0.69	T
PROVEAN	Pathogenic	-8.4	D;D;D
REVEL	Pathogenic	0.95
Sift	Pathogenic	0.0	D;D;D
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	.;D;.
Vest4		0.93
MVP		0.95
MPC		0.48
ClinPred		0.99	D
GERP RS		5.5
Varity_R		0.97
gMVP		0.95

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: rs137852870; hg19: chr19-41930487;