21-43065481-G-C

Variant names:

• chr21-43065481-G-C
• rs121964973
• NM_000071.3:c.572C>G
• CBS p.Thr191Arg

Variant summary

Our verdict is Likely pathogenic. The variant received 7 ACMG points: 7P and 0B. PM5 PP2 PP3_Strong

The NM_000071.3(CBS):​c.572C>G​(p.Thr191Arg) variant causes a missense change involving the alteration of a 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. T191K) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 4)
• Consequence: CBS NM_000071.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 8.36
• 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: ClinGen, Genomics England PanelApp, Orphanet, Myriad Women's Health, G2P, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Likely_pathogenic. The variant received 7 ACMG points.

• PM5: Other missense variant is known to change same aminoacid residue: Variant chr21-43065481-G-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 431934.
• 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, 0.989

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

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CBS	NM_000071.3	MANE Select	c.572C>G	p.Thr191Arg	missense	Exon 7 of 17	NP_000062.1	P35520-1
	CBS	NM_001178008.3		c.572C>G	p.Thr191Arg	missense	Exon 7 of 17	NP_001171479.1	P35520-1
	CBS	NM_001178009.3		c.572C>G	p.Thr191Arg	missense	Exon 7 of 18	NP_001171480.1	P35520-1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CBS	ENST00000398165.8	TSL:1 MANE Select	c.572C>G	p.Thr191Arg	missense	Exon 7 of 17	ENSP00000381231.4	P35520-1
	CBS	ENST00000352178.9	TSL:1	c.572C>G	p.Thr191Arg	missense	Exon 7 of 17	ENSP00000344460.5	P35520-1
	CBS	ENST00000359624.7	TSL:1	c.572C>G	p.Thr191Arg	missense	Exon 7 of 18	ENSP00000352643.3	P35520-1

Frequencies

GnomAD3 genomes Cov.: 4

GnomAD4 exome Cov.: 0

GnomAD4 genome Cov.: 4

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.96
BayesDel_addAF	Pathogenic	0.43	D
BayesDel_noAF	Pathogenic	0.38
CADD	Pathogenic	28
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.99	D
Eigen	Pathogenic	0.80
Eigen_PC	Uncertain	0.64
FATHMM_MKL	Uncertain	0.90	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Pathogenic	0.93	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.2	H
PhyloP100		8.4
PrimateAI	Uncertain	0.76	T
PROVEAN	Pathogenic	-5.7	D
REVEL	Pathogenic	0.95
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0010	D
Varity_R		0.98
gMVP		0.97
Mutation Taster		=4/96	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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Other links and lift over

dbSNP: rs121964973;

hg19: chr21-44485591;