21-43056804-C-G

Variant names:

• chr21-43056804-C-G
• rs750311684
• NM_000071.3:c.1551G>C
• CBS p.Gln517His

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 1P and 0B. PP2

The NM_000071.3(CBS):​c.1551G>C​(p.Gln517His) variant causes a missense, splice region change involving the alteration of a non-conserved nucleotide. 3/3 splice prediction tools predict no significant impact on normal splicing. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. Q517Q) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 0)
• Consequence: CBS NM_000071.3 missense, splice_region
• Scores: Splicing: ADA: 0.0001960
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: -0.543
• 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: Uncertain_significance. The variant received 1 ACMG points.

• 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.

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.1551G>C	p.Gln517His	missense splice_region	Exon 16 of 17	NP_000062.1	P35520-1
	CBS	NM_001178008.3		c.1551G>C	p.Gln517His	missense splice_region	Exon 16 of 17	NP_001171479.1	P35520-1
	CBS	NM_001178009.3		c.1551G>C	p.Gln517His	missense splice_region	Exon 16 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.1551G>C	p.Gln517His	missense splice_region	Exon 16 of 17	ENSP00000381231.4	P35520-1
	CBS	ENST00000352178.9	TSL:1	c.1551G>C	p.Gln517His	missense splice_region	Exon 16 of 17	ENSP00000344460.5	P35520-1
	CBS	ENST00000359624.7	TSL:1	c.1551G>C	p.Gln517His	missense splice_region	Exon 16 of 18	ENSP00000352643.3	P35520-1

Frequencies

GnomAD3 genomes Cov.: 0

GnomAD2 exomes AF: 0.00 AC: 0 AN: 156084 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	Benign	0.33
BayesDel_addAF	Pathogenic	0.30	D
BayesDel_noAF	Pathogenic	0.19
CADD	Benign	17
DANN	Uncertain	0.98
DEOGEN2	Uncertain	0.63	D
Eigen	Benign	0.13
Eigen_PC	Benign	-0.0059
FATHMM_MKL	Benign	0.66	D
LIST_S2	Benign	0.83	T
M_CAP	Uncertain	0.20	D
MetaRNN	Uncertain	0.74	D
MetaSVM	Benign	-0.42	T
MutationAssessor	Pathogenic	3.0	M
PhyloP100		-0.54
PrimateAI	Benign	0.40	T
PROVEAN	Benign	-1.8	N
REVEL	Pathogenic	0.67
Sift	Benign	0.034	D
Sift4G	Benign	0.10	T
Varity_R		0.12
gMVP		0.76
Mutation Taster		=52/48	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.00020
dbscSNV1_RF	Benign	0.098
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: rs750311684;

hg19: chr21-44476914;