21-43065646-G-C

Variant names:

• chr21-43065646-G-C
• rs754246295
• NM_000071.3:c.501C>G

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PM1 PP2 PP3_Moderate

The NM_000071.3(CBS):​c.501C>G​(p.Ile167Met) variant causes a missense change involving the alteration of a non-conserved nucleotide. 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. I167V) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 0)
• Consequence: CBS NM_000071.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.161
• 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: G2P, Orphanet, Labcorp Genetics (formerly Invitae), Myriad Women’s Health, PanelApp Australia, ClinGen, Genomics England PanelApp

ACMG classification

Our verdict: Uncertain_significance. The variant received 5 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 7 uncertain in NM_000071.3
• 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, 0.91

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.501C>G	p.Ile167Met	missense	Exon 6 of 17	NP_000062.1
	CBS	NM_001178008.3		c.501C>G	p.Ile167Met	missense	Exon 6 of 17	NP_001171479.1
	CBS	NM_001178009.3		c.501C>G	p.Ile167Met	missense	Exon 6 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.501C>G	p.Ile167Met	missense	Exon 6 of 17	ENSP00000381231.4
	CBS	ENST00000352178.9	TSL:1	c.501C>G	p.Ile167Met	missense	Exon 6 of 17	ENSP00000344460.5
	CBS	ENST00000359624.7	TSL:1	c.501C>G	p.Ile167Met	missense	Exon 6 of 18	ENSP00000352643.3

Frequencies

GnomAD3 genomes Cov.: 0

GnomAD2 exomes AF: 0.00 AC: 0 AN: 186604 AF XY: 0.00

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

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.41
BayesDel_addAF	Pathogenic	0.50	D
BayesDel_noAF	Pathogenic	0.49
CADD	Benign	22
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.99	D
Eigen	Uncertain	0.25
Eigen_PC	Benign	0.097
FATHMM_MKL	Benign	0.71	D
LIST_S2	Uncertain	0.97	D
M_CAP	Pathogenic	0.88	D
MetaRNN	Pathogenic	0.91	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.6	H
PhyloP100		0.16
PrimateAI	Uncertain	0.62	T
PROVEAN	Uncertain	-2.8	D
REVEL	Pathogenic	0.87
Sift	Uncertain	0.0010	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.91
MutPred		0.68		Gain of disorder (P = 0.0809)
MVP		0.89
MPC		1.1
ClinPred		0.99	D
GERP RS		1.1
Varity_R		0.95
gMVP		0.84
Mutation Taster		=15/85	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: rs754246295; hg19: chr21-44485756;