21-43065645-C-A

Position:

• chr21-43065645-C-A

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM5 PP3_Moderate

The NM_000071.3(CBS):​c.502G>T​(p.Val168Leu) variant causes a missense change. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V168A) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 0)
• Consequence: CBS NM_000071.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 6.78

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 (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a strand (size 6) in uniprot entity CBS_HUMAN there are 4 pathogenic changes around while only 0 benign (100%) in NM_000071.3
• PM5: Other missense variant is known to change same aminoacid residue: Variant chrnull-null-null-null is described in UniProt as null.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.922

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CBS	NM_000071.3	c.502G>T	p.Val168Leu	missense_variant	6/17	ENST00000398165.8	NP_000062.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CBS	ENST00000398165.8	c.502G>T	p.Val168Leu	missense_variant	6/17	1	NM_000071.3	ENSP00000381231.4

Frequencies

GnomAD3 genomes Cov.: 0

GnomAD3 exomes AF: 0.00000535 AC: 1 AN: 186900 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 100190

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000352

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS 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

Alfa AF: 0.0000370 Hom.: 0

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.91
BayesDel_addAF	Pathogenic	0.50	D
BayesDel_noAF	Pathogenic	0.48
CADD	Uncertain	26
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.97	D;D;D;D;.
Eigen	Pathogenic	0.69
Eigen_PC	Uncertain	0.62
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Pathogenic	0.99	.;.;.;D;D
M_CAP	Pathogenic	0.51	D
MetaRNN	Pathogenic	0.92	D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.3	M;M;M;M;.
PrimateAI	Uncertain	0.74	T
PROVEAN	Uncertain	-2.5	D;D;D;D;D
REVEL	Pathogenic	0.91
Sift	Uncertain	0.010	D;D;D;D;D
Sift4G	Uncertain	0.016	D;D;D;D;D
Polyphen		0.84	P;P;P;P;.
Vest4		0.90
MutPred		0.75		Loss of catalytic residue at V168 (P = 0.0688);Loss of catalytic residue at V168 (P = 0.0688);Loss of catalytic residue at V168 (P = 0.0688);Loss of catalytic residue at V168 (P = 0.0688);Loss of catalytic residue at V168 (P = 0.0688);
MVP		0.95
MPC		1.0
ClinPred		0.95	D
GERP RS		4.6
Varity_R		0.96
gMVP		0.85

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

Publications

LitVar

Other links and lift over

dbSNP: rs121964970; hg19: chr21-44485755;