rs371214833

chr21-43059244-A-G

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 0P and 2B. BP4_Moderate

The NM_000071.3(CBS):c.1205T>C(p.Leu402Pro) variant causes a missense change involving the alteration of a non-conserved nucleotide. In-silico tool predicts a benign outcome for this variant. 14/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency: Genomes: not found (cov: 0)
• Consequence: CBS NM_000071.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:4
• Conservation: PhyloP100: 1.91

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]

ACMG classification

Verdict is Likely_benign. Variant got -2 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.23572749).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CBS	NM_000071.3	c.1205T>C	p.Leu402Pro	missense_variant	13/17	ENST00000398165.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CBS	ENST00000398165.8	c.1205T>C	p.Leu402Pro	missense_variant	13/17	1	NM_000071.3	P1

Frequencies

GnomAD3 genomes Cov.: 0

GnomAD3 exomes AF: 0.0000398 AC: 10 AN: 251172 Hom.: 0 AF XY: 0.0000294 AC XY: 4 AN XY: 135836

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000231

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: 0.00000880

Gnomad OTH exome AF: 0.000163

GnomAD4 exome Cov.: 0

GnomAD4 genome Cov.: 0

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000116 AC: 1

ExAC AF: 0.0000247 AC: 3

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Classic homocystinuria Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 12, 2018	This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -
Uncertain significance, no assertion criteria provided	clinical testing	Natera, Inc.	Sep 16, 2020	- -

Familial thoracic aortic aneurysm and aortic dissection Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Oct 01, 2021

The c.1205T>C (p.L402P) alteration is located in exon 13 (coding exon 11) of the CBS gene. This alteration results from a T to C substitution at nucleotide position 1205, causing the leucine (L) at amino acid position 402 to be replaced by a proline (P). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

HYPERHOMOCYSTEINEMIA, THROMBOTIC, CBS-RELATED Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Jan 02, 2024

This sequence change replaces leucine, which is neutral and non-polar, with proline, which is neutral and non-polar, at codon 402 of the CBS protein (p.Leu402Pro). This variant is present in population databases (rs371214833, gnomAD 0.03%). This variant has not been reported in the literature in individuals affected with CBS-related conditions. ClinVar contains an entry for this variant (Variation ID: 471355). 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 not expected to disrupt CBS protein function with a negative predictive value of 95%. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.089
BayesDel_addAF	Benign	-0.079	T
BayesDel_noAF	Uncertain	-0.050
Cadd	Benign	15
Dann	Benign	0.22
DEOGEN2	Benign	0.35	T;T;T;T
Eigen	Benign	-0.70
Eigen_PC	Benign	-0.80
FATHMM_MKL	Benign	0.24	N
M_CAP	Benign	0.020	T
MetaRNN	Benign	0.24	T;T;T;T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	1.7	L;L;L;L
MutationTaster	Benign	1.0	N;N;N;N;N;N;N;N;N;N;N;N
PrimateAI	Benign	0.40	T
PROVEAN	Benign	1.3	N;N;N;N
REVEL	Uncertain	0.42
Sift	Benign	0.36	T;T;T;T
Sift4G	Benign	0.38	T;T;T;T
Polyphen		0.0	B;B;B;B
Vest4		0.54
MVP		0.60
MPC		0.56
ClinPred		0.042	T
GERP RS		0.76
Varity_R		0.13
gMVP		0.84

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: rs371214833; hg19: chr21-44479354;