rs786204499

Variant names:

• chr21-43065249-CA-C
• rs775351239
• NM_000071.3:c.689delT

Variant summary

Our verdict is Pathogenic. The variant received 16 ACMG points: 16P and 0B. PVS1 PP5_Very_Strong

The NM_000071.3(CBS):​c.689delT​(p.Leu230ArgfsTer39) variant causes a frameshift change involving the alteration of a conserved nucleotide. Variant has been reported in ClinVar as Pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. L230L) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: 𝑓 0.000016 (1 hom., cov: 16)
  • Exomes 𝑓: 0.000020 (9 hom.)
  • Failed GnomAD Quality Control
• Consequence: CBS NM_000071.3 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 7.87
• Publications: 2 publications found

Genes affected

CBS (HGNC:1550): (cystathionine beta-synthase) The protein encoded by this gene acts as a homotetramer to catalyze the conversion of homocysteine to cystathionine, the first step in the transsulfuration pathway. The encoded protein is allosterically activated by adenosyl-methionine and uses pyridoxal phosphate as a cofactor. Defects in this gene can cause cystathionine beta-synthase deficiency (CBSD), which can lead to homocystinuria. This gene is a major contributor to cellular hydrogen sulfide production. Multiple alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Feb 2016]

CBS Gene-Disease associations (from GenCC):

• classic homocystinuria

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Orphanet, Labcorp Genetics (formerly Invitae), Myriad Women’s Health, PanelApp Australia, ClinGen, Genomics England PanelApp

ACMG classification

Our verdict: Pathogenic. The variant received 16 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PP5: Variant 21-43065249-CA-C is Pathogenic according to our data. Variant chr21-43065249-CA-C is described in ClinVar as Pathogenic. ClinVar VariationId is 188829.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000071.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CBS	NM_000071.3	MANE Select	c.689delT	p.Leu230ArgfsTer39	frameshift	Exon 8 of 17	NP_000062.1
	CBS	NM_001178008.3		c.689delT	p.Leu230ArgfsTer39	frameshift	Exon 8 of 17	NP_001171479.1
	CBS	NM_001178009.3		c.689delT	p.Leu230ArgfsTer39	frameshift	Exon 8 of 18	NP_001171480.1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CBS	ENST00000398165.8	TSL:1 MANE Select	c.689delT	p.Leu230ArgfsTer39	frameshift	Exon 8 of 17	ENSP00000381231.4
	CBS	ENST00000352178.9	TSL:1	c.689delT	p.Leu230ArgfsTer39	frameshift	Exon 8 of 17	ENSP00000344460.5
	CBS	ENST00000359624.7	TSL:1	c.689delT	p.Leu230ArgfsTer39	frameshift	Exon 8 of 18	ENSP00000352643.3

Frequencies

GnomAD3 genomes AF: 0.0000157 AC: 2 AN: 127780 Hom.: 1 Cov.: 16

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: 0.0000357

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.00000398 AC: 1 AN: 251410 AF XY: 0.00000736

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 FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 0.0000201 AC: 26 AN: 1292254 Hom.: 9 Cov.: 28 AF XY: 0.0000280 AC XY: 18 AN XY: 643890

African (AFR) AF: 0.00 AC: 0 AN: 31674

American (AMR) AF: 0.00 AC: 0 AN: 42962

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 23012

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

South Asian (SAS) AF: 0.00 AC: 0 AN: 80348

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 49128

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5198

European-Non Finnish (NFE) AF: 0.0000269 AC: 26 AN: 965886

Other (OTH) AF: 0.00 AC: 0 AN: 54372

GnomAD4 genome AF: 0.0000157 AC: 2 AN: 127780 Hom.: 1 Cov.: 16 AF XY: 0.00 AC XY: 0 AN XY: 61994

African (AFR) AF: 0.00 AC: 0 AN: 35458

American (AMR) AF: 0.00 AC: 0 AN: 12824

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 2952

East Asian (EAS) AF: 0.00 AC: 0 AN: 5072

South Asian (SAS) AF: 0.00 AC: 0 AN: 3910

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 8728

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 252

European-Non Finnish (NFE) AF: 0.0000357 AC: 2 AN: 56096

Other (OTH) AF: 0.00 AC: 0 AN: 1704

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

ClinVar submissions as Germline

Significance: Pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
3	-	-	Classic homocystinuria (3)
1	-	-	Homocystinuria (1)
1	-	-	HYPERHOMOCYSTEINEMIA, THROMBOTIC, CBS-RELATED (1)
1	-	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		7.9
Mutation Taster		=0/200	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs775351239; hg19: chr21-44485359;