rs1555875292

Variant names:

• chr21-43066242-C-A
• rs1555875292
• NM_000071.3:c.451+1G>T

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PVS1_Moderate PP5_Very_Strong

The NM_000071.3(CBS):​c.451+1G>T variant causes a splice donor, intron change. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 16)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: CBS NM_000071.3 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 6.84
• Publications: 0 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: Labcorp Genetics (formerly Invitae), G2P, ClinGen, Orphanet, Myriad Women’s Health, Genomics England PanelApp

ACMG classification

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

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.08152174 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PP5: Variant 21-43066242-C-A is Pathogenic according to our data. Variant chr21-43066242-C-A is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 552801.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.451+1G>T		splice_donor intron	N/A	NP_000062.1	P35520-1
	CBS	NM_001178008.3		c.451+1G>T		splice_donor intron	N/A	NP_001171479.1	P35520-1
	CBS	NM_001178009.3		c.451+1G>T		splice_donor intron	N/A	NP_001171480.1	P35520-1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CBS	ENST00000398165.8	TSL:1 MANE Select	c.451+1G>T		splice_donor intron	N/A	ENSP00000381231.4	P35520-1
	CBS	ENST00000352178.9	TSL:1	c.451+1G>T		splice_donor intron	N/A	ENSP00000344460.5	P35520-1
	CBS	ENST00000359624.7	TSL:1	c.451+1G>T		splice_donor intron	N/A	ENSP00000352643.3	P35520-1

Frequencies

GnomAD3 genomes Cov.: 16

GnomAD4 exome Data not reliable, filtered out with message: AC0;AS_VQSR AF: 0.00 AC: 0 AN: 1234830 Hom.: 0 Cov.: 27 AF XY: 0.00 AC XY: 0 AN XY: 617180

African (AFR) AF: 0.00 AC: 0 AN: 18562

American (AMR) AF: 0.00 AC: 0 AN: 42302

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 22000

East Asian (EAS) AF: 0.00 AC: 0 AN: 38866

South Asian (SAS) AF: 0.00 AC: 0 AN: 76530

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 40398

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 4430

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 940134

Other (OTH) AF: 0.00 AC: 0 AN: 51608

GnomAD4 genome Cov.: 16

ClinVar

ClinVar submissions

Significance: Likely pathogenic

Revision: criteria provided, multiple submitters, no conflicts

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

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.22	D
BayesDel_noAF	Uncertain	0.080
CADD	Pathogenic	33
DANN	Uncertain	0.99
Eigen	Pathogenic	0.97
Eigen_PC	Pathogenic	0.76
FATHMM_MKL	Uncertain	0.90	D
PhyloP100		6.8
GERP RS		5.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Mutation Taster		=0/100	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.95
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.46		Position offset: -3
DS_DL_spliceai		0.99		Position offset: 1

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

Other links and lift over

dbSNP: rs1555875292; hg19: chr21-44486352;