rs1555874803

Variant names:

• chr21-43065256-T-C
• rs1555874803
• NM_000071.3:c.683A>G
• CBS p.Asn228Ser

Variant summary

Our verdict is Pathogenic. The variant received 23 ACMG points: 23P and 0B. PS3 PM1 PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_000071.3(CBS):​c.683A>G​(p.Asn228Ser) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). ClinVar reports functional evidence for this variant: "SCV001544670: Experimental studies have shown that this missense change affects CBS function (PMID:14635102, 17540596, 20066033, 22267502)." and additional evidence is available in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. N228K) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 15)
• Consequence: CBS NM_000071.3 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3 U:1
• Conservation: PhyloP100: 6.74
• 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: ClinGen, Genomics England PanelApp, Orphanet, Myriad Women's Health, G2P, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Pathogenic. The variant received 23 ACMG points.

• PS3: PS3 evidence extracted from ClinVar submissions: SCV001544670: Experimental studies have shown that this missense change affects CBS function (PMID: 14635102, 17540596, 20066033, 22267502).; SCV004037666: "Several publications reports experimental evidence evaluating an impact on protein function, finding that the variant results in a nonfunctional protein in yeast colonies, almost entirely ablating CBS activity (Kruger_2003, Singh_2010, Wei_2010, Mayfield_2012)." PMID:14635102, 20455263, 22267502, 20066033
• PM1: In a hotspot region, there are 8 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 7 uncertain in NM_000071.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr21-43065255-G-C is described in ClinVar as Pathogenic. ClinVar VariationId is 928858.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 107 curated pathogenic missense variants (we use a threshold of 10). The gene has 4 curated benign missense variants. Gene score misZ: 0.8318 (below the threshold of 3.09). Trascript score misZ: NaN (below the threshold of 3.09). GenCC associations: The gene is linked to classic homocystinuria.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.979
• PP5: Variant 21-43065256-T-C is Pathogenic according to our data. Variant chr21-43065256-T-C is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 553698.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.683A>G	p.Asn228Ser	missense	Exon 8 of 17	NP_000062.1	P35520-1
	CBS	NM_001178008.3		c.683A>G	p.Asn228Ser	missense	Exon 8 of 17	NP_001171479.1	P35520-1
	CBS	NM_001178009.3		c.683A>G	p.Asn228Ser	missense	Exon 8 of 18	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.683A>G	p.Asn228Ser	missense	Exon 8 of 17	ENSP00000381231.4	P35520-1
	CBS	ENST00000352178.9	TSL:1	c.683A>G	p.Asn228Ser	missense	Exon 8 of 17	ENSP00000344460.5	P35520-1
	CBS	ENST00000359624.7	TSL:1	c.683A>G	p.Asn228Ser	missense	Exon 8 of 18	ENSP00000352643.3	P35520-1

Frequencies

GnomAD3 genomes Cov.: 15

GnomAD4 exome Cov.: 28

GnomAD4 genome Cov.: 15

Alfa AF: 0.0000611 Hom.: 0

ClinVar

ClinVar submissions

Significance: Pathogenic/Likely pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
1	1	-	Classic homocystinuria (2)
1	-	-	Homocystinuria (1)
1	-	-	HYPERHOMOCYSTEINEMIA, THROMBOTIC, CBS-RELATED (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.47
BayesDel_addAF	Pathogenic	0.22	D
BayesDel_noAF	Uncertain	0.080
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.98	D
Eigen	Pathogenic	0.93
Eigen_PC	Pathogenic	0.80
FATHMM_MKL	Uncertain	0.90	D
LIST_S2	Pathogenic	1.0	D
M_CAP	Pathogenic	0.90	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.5	H
PhyloP100		6.7
PrimateAI	Uncertain	0.58	T
PROVEAN	Pathogenic	-5.0	D
REVEL	Pathogenic	0.90
Sift	Pathogenic	0.0	D
Sift4G	Uncertain	0.0030	D
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.99
gMVP		0.93
Mutation Taster		=0/100	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
Splicevardb		2.0
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Other links and lift over

dbSNP: rs1555874803;

hg19: chr21-44485366;