rs1554194690

Variant names:

• chr6-80200998-GAGTGATGTTACTCT-G
• rs1554194690
• NM_183050.4:c.811_824delGATGTTACTCTAGT

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PVS1 PP5_Moderate

The NM_183050.4(BCKDHB):​c.811_824delGATGTTACTCTAGT​(p.Asp271CysfsTer25) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000685 in 1,460,762 control chromosomes in the GnomAD database, with no homozygous occurrence. It is difficult to determine the true allele frequency of this variant because it is of type DEL_BIG, and the frequency of such variant types in population databases may be underestimated and unreliable. Variant has been reported in ClinVar as Pathogenic (★). Synonymous variant affecting the same amino acid position (i.e. D271D) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: BCKDHB NM_183050.4 frameshift
• Clinical Significance: Pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 9.44
• Publications: 0 publications found

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]

BCKDHB Gene-Disease associations (from GenCC):

• maple syrup urine disease type 1B

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen, G2P, Myriad Women’s Health
• maple syrup urine disease

  Inheritance: AR Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• classic maple syrup urine disease

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• intermediate maple syrup urine disease

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• intermittent maple syrup urine disease

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• thiamine-responsive maple syrup urine disease

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PP5: Variant 6-80200998-GAGTGATGTTACTCT-G is Pathogenic according to our data. Variant chr6-80200998-GAGTGATGTTACTCT-G is described in ClinVar as Pathogenic. ClinVar VariationId is 557213.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
BCKDHB	NM_183050.4	c.811_824delGATGTTACTCTAGT	p.Asp271CysfsTer25	frameshift_variant	Exon 7 of 10	ENST00000320393.9	NP_898871.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
BCKDHB	ENST00000320393.9	c.811_824delGATGTTACTCTAGT	p.Asp271CysfsTer25	frameshift_variant	Exon 7 of 10	1	NM_183050.4	ENSP00000318351.5
BCKDHB	ENST00000356489.9	c.811_824delGATGTTACTCTAGT	p.Asp271CysfsTer25	frameshift_variant	Exon 7 of 11	1		ENSP00000348880.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1460762 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 726746

African (AFR) AF: 0.00 AC: 0 AN: 33432

American (AMR) AF: 0.00 AC: 0 AN: 44692

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26108

East Asian (EAS) AF: 0.00 AC: 0 AN: 39674

South Asian (SAS) AF: 0.00 AC: 0 AN: 86246

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53408

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 9.00e-7 AC: 1 AN: 1111098

Other (OTH) AF: 0.00 AC: 0 AN: 60340

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, single submitter

Submissions by phenotype

Maple syrup urine disease Pathogenic:1

Aug 30, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Asp271Cysfs*25) 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). For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 557213). This variant is also known as c.808_821del, p.Ser270_Leu274del. This premature translational stop signal has been observed in individual(s) with maple syrup urine disease (PMID: 17922217). This variant is not present in population databases (gnomAD no frequency). -

Maple syrup urine disease type 1A Pathogenic:1

Mar 19, 2018

Counsyl

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		9.4
Mutation Taster		=3/197	disease causing (ClinVar)

Splicing

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

Other links and lift over

dbSNP: rs1554194690; hg19: chr6-80910715;