21-43062358-G-A

Variant names:

• chr21-43062358-G-A
• rs777919630
• NM_000071.3:c.992C>T

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PM1 PM5 PP2 PP3_Strong PP5

The NM_000071.3(CBS):​c.992C>T​(p.Ala331Val) variant causes a missense change. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A331E) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 0)
• Consequence: CBS NM_000071.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:4 U:2
• Conservation: PhyloP100: 6.80
• Publications: 16 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 10 ACMG points.

• PM1: In a hotspot region, there are 8 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 6 uncertain in NM_000071.3
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr21-43062358-G-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 212857.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, 0.994
• PP5: Variant 21-43062358-G-A is Pathogenic according to our data. Variant chr21-43062358-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 193793.

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

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CBS	NM_000071.3	MANE Select	c.992C>T	p.Ala331Val	missense	Exon 11 of 17	NP_000062.1
	CBS	NM_001178008.3		c.992C>T	p.Ala331Val	missense	Exon 11 of 17	NP_001171479.1
	CBS	NM_001178009.3		c.992C>T	p.Ala331Val	missense	Exon 11 of 18	NP_001171480.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CBS	ENST00000398165.8	TSL:1 MANE Select	c.992C>T	p.Ala331Val	missense	Exon 11 of 17	ENSP00000381231.4
	CBS	ENST00000352178.9	TSL:1	c.992C>T	p.Ala331Val	missense	Exon 11 of 17	ENSP00000344460.5
	CBS	ENST00000359624.7	TSL:1	c.992C>T	p.Ala331Val	missense	Exon 11 of 18	ENSP00000352643.3

Frequencies

GnomAD3 genomes Cov.: 0

GnomAD2 exomes AF: 0.00000797 AC: 2 AN: 250866 AF XY: 0.0000147

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: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome Cov.: 0

GnomAD4 genome Cov.: 0

ClinVar

ClinVar submissions as Germline

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
2	-	-	Classic homocystinuria (2)
1	-	-	Familial thoracic aortic aneurysm and aortic dissection (1)
1	-	-	HYPERHOMOCYSTEINEMIA, THROMBOTIC, CBS-RELATED (1)
-	1	-	Intellectual disability (1)
-	1	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.35
BayesDel_addAF	Pathogenic	0.23	D
BayesDel_noAF	Pathogenic	0.27
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.97	D
Eigen	Uncertain	0.45
Eigen_PC	Uncertain	0.38
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.95	D
M_CAP	Pathogenic	0.53	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.1	M
PhyloP100		6.8
PrimateAI	Benign	0.38	T
PROVEAN	Uncertain	-2.9	D
REVEL	Pathogenic	0.70
Sift	Uncertain	0.0040	D
Sift4G	Uncertain	0.0040	D
Polyphen		0.94	P
Vest4		0.88
MutPred		0.93		Gain of helix (P = 0.062)
MVP		0.88
MPC		0.53
ClinPred		0.88	D
GERP RS		5.2
Varity_R		0.47
gMVP		0.91
Mutation Taster		=0/100	disease causing

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: rs777919630; hg19: chr21-44482468;