NM_000071.3:c.770C>T

Variant names:

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PP3_StrongPP5_Very_Strong

The NM_000071.3(CBS):c.770C>T(p.Thr257Met) variant causes a missense change involving the alteration of a conserved nucleotide. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★).

Frequency

Genomes: 𝑓 0.0 ( 0 hom., cov: 3)

Exomes 𝑓: 0.000040 ( 1 hom. )

Failed GnomAD Quality Control

Consequence

CBS
NM_000071.3 missense

Scores

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:10

Conservation

PhyloP100: 8.70

Variant links:

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 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Pathogenic. Variant got 12 ACMG points.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.997

PP5

Variant 21-43063958-G-A is Pathogenic according to our data. Variant chr21-43063958-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 188927.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr21-43063958-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CBS	NM_000071.3 link	c.770C>T	p.Thr257Met	missense_variant	Exon 9 of 17	ENST00000398165.8	NP_000062.1	P35520-1Q9NTF0

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CBS	ENST00000398165.8 link	c.770C>T	p.Thr257Met	missense_variant	Exon 9 of 17	1	NM_000071.3	ENSP00000381231.4		P35520-1

Frequencies

GnomAD3 genomes

AF:

0.00

AC:

AN:

7924

Hom.:

Cov.:

FAILED QC

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:

0.00

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000362

AC:

AN:

248606

Hom.:

AF XY:

0.0000520

AC XY:

AN XY:

134572

show subpopulations

Gnomad AFR exome

AF:

0.0000629

Gnomad AMR exome

AF:

0.0000871

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.000132

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.000165

GnomAD4 exome

Data not reliable, filtered out with message: AS_VQSR

AF:

0.0000399

AC:

AN:

200730

Hom.:

Cov.:

AF XY:

0.0000375

AC XY:

AN XY:

106574

show subpopulations

Gnomad4 AFR exome

AF:

0.000283

Gnomad4 AMR exome

AF:

0.000252

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.0000361

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.0000192

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

Data not reliable, filtered out with message: AC0;AS_VQSR

AF:

0.00

AC:

AN:

7924

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

3534

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000868

Hom.:

ExAC

AF:

0.0000577

AC:

EpiCase

AF:

0.000109

EpiControl

AF:

0.00

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:10

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Classic homocystinuria

Pathogenic:5

Mar 20, 2019

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.Thr257Met variant in CBS has been reported in at least 7 individuals with homocystinuria (4 homozygous and 3 compound heterozygous) and segregated with disease in 2 affected individuals from 2 families (Ibrahim 2018, Lee 2005, Li 2018, Sebastio 1995, Urreizti 2006, Zaidi 2012). It has also been identified in 12/279982 total chromosomes by gnomAD (http://gnomad.broadinstitute.org). However, this frequency is low enough to be consistent with a recessive carrier frequency. This variant has also been reported in ClinVar (Variation ID 188927). Computational prediction tools and conservation analysis suggest that this variant may impact the protein, though this information is not predictive enough to determine pathogenicity. In vitro functional studies support an impact on protein function (Mayfield 2012, Yadav 2012, Sebastio 1995, Lee 2005). In summary, this variant meets criteria to be classified as pathogenic for autosomal recessive homocystinuria. ACMG/AMP Criteria applied: PS3, PM3_Strong, PM2_Supporting, PP1, PP3, PP4. -

Aug 21, 2014

Counsyl

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: literature only

- -

Mar 03, 2024

Baylor Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Apr 13, 2024

Genomic Research Center, Shahid Beheshti University of Medical Sciences

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Sep 16, 2020

Natera, Inc.

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Hyperhomocysteinemia

Pathogenic:1

Apr 13, 2024

Genomic Research Center, Shahid Beheshti University of Medical Sciences

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

See cases

Pathogenic:1

Jan 11, 2023

Institute of Human Genetics, University Hospital Muenster

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

ACMG categories: PS3,PM1,PM2,PP3,PP5 -

HYPERHOMOCYSTEINEMIA, THROMBOTIC, CBS-RELATED

Pathogenic:1

Dec 23, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces threonine, which is neutral and polar, with methionine, which is neutral and non-polar, at codon 257 of the CBS protein (p.Thr257Met). This variant is present in population databases (rs758236584, gnomAD 0.01%). This missense change has been observed in individual(s) with homocystinuria (PMID: 7762555, 16205833, 16479318, 21517828). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 188927). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt CBS protein function with a positive predictive value of 95%. Experimental studies have shown that this missense change affects CBS function (PMID: 7762555, 16205833, 22267502, 22977242). For these reasons, this variant has been classified as Pathogenic. -

not provided

Pathogenic:1

Oct 16, 2020

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at a significant frequency in large population cohorts (Lek et al., 2016); Reported in ClinVar but additional evidence is not available (ClinVar Variant ID #188927; Landrum et al., 2016); In vitro functional studies show a marked decrease in CBS enzymatic activity (Sebastio et al., 1995; Lee et al., 2005; Yadav et al., 2012); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 22977242, 21517828, 22267502, 7762555, 29600437, 29508359, 16205833, 23685761, 7967489, 16479318, 31589614) -

Homocystinuria

Pathogenic:1

Dec 24, 2018

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: CBS c.770C>T (p.Thr257Met) results in a non-conservative amino acid change located in the pyridoxal-phosphate dependent enzyme domain (IPR001926) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 4.7e-05 in 274572 control chromosomes (gnomAD). This frequency is not higher than expected for a pathogenic variant in CBS causing Homocystinuria (4.7e-05 vs 0.003), allowing no conclusion about variant significance. c.770C>T has been reported in the literature in multiple homozygous (Sebastio 1995, Zaidi 2012) and compound heterozygous (e.g. Lee 2005) individuals affected with Homocystinuria. Moreover, the variant was shown to segregate with the disease in one of these families (Sebastio 1995). These data indicate that the variant is very likely to be associated with disease. These publications also reported experimental evidence evaluating an impact on protein function. The most pronounced variant effect results in <10% of normal activity (Sebastio 1995, Lee 2005). One clinical diagnostic laboratory has submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation, and classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.86

BayesDel_addAF

Pathogenic

0.42

BayesDel_noAF

Pathogenic

0.60

CADD

Pathogenic

DANN

Pathogenic

1.0

DEOGEN2

Pathogenic

0.99

D;D;D;D

Eigen

Pathogenic

0.84

Eigen_PC

Uncertain

0.64

FATHMM_MKL

Uncertain

0.96

LIST_S2

Pathogenic

1.0

.;.;.;D

M_CAP

Pathogenic

0.95

MetaRNN

Pathogenic

1.0

D;D;D;D

MetaSVM

Pathogenic

0.97

MutationAssessor

Pathogenic

4.8

H;H;H;H

PrimateAI

Uncertain

0.69

PROVEAN

Pathogenic

-6.0

D;D;D;D

REVEL

Pathogenic

0.96

Sift

Pathogenic

0.0

D;D;D;D

Sift4G

Pathogenic

0.0

D;D;D;D

Polyphen

1.0

D;D;D;D

Vest4

0.98

MutPred

0.97

Gain of MoRF binding (P = 0.0819);Gain of MoRF binding (P = 0.0819);Gain of MoRF binding (P = 0.0819);Gain of MoRF binding (P = 0.0819);

MVP

0.94

MPC

1.1

ClinPred

0.99

GERP RS

4.1

Varity_R

0.99

gMVP

0.96

Splicing

Name

Calibrated prediction

Score

Prediction

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

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over