chr20-23635321-G-A

Position:

• chr20-23635321-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 4P and 4B. PP3_Strong BS2

The NM_000099.4(CST3):​c.290C>T​(p.Thr97Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000349 in 1,461,616 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.000035 (0 hom.)
• Consequence: CST3 NM_000099.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.57

Genes affected

CST3 (HGNC:2475): (cystatin C) The cystatin superfamily encompasses proteins that contain multiple cystatin-like sequences. Some of the members are active cysteine protease inhibitors, while others have lost or perhaps never acquired this inhibitory activity. There are three inhibitory families in the superfamily, including the type 1 cystatins (stefins), type 2 cystatins and the kininogens. The type 2 cystatin proteins are a class of cysteine proteinase inhibitors found in a variety of human fluids and secretions, where they appear to provide protective functions. The cystatin locus on chromosome 20 contains the majority of the type 2 cystatin genes and pseudogenes. This gene is located in the cystatin locus and encodes the most abundant extracellular inhibitor of cysteine proteases, which is found in high concentrations in biological fluids and is expressed in virtually all organs of the body. A mutation in this gene has been associated with amyloid angiopathy. Expression of this protein in vascular wall smooth muscle cells is severely reduced in both atherosclerotic and aneurysmal aortic lesions, establishing its role in vascular disease. In addition, this protein has been shown to have an antimicrobial function, inhibiting the replication of herpes simplex virus. Alternative splicing results in multiple transcript variants encoding a single protein. [provided by RefSeq, Nov 2014]

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PP3: MetaRNN computational evidence supports a deleterious effect, 0.985
• BS2: High AC in GnomAdExome4 at 51 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CST3	NM_000099.4	c.290C>T	p.Thr97Ile	missense_variant	2/3	ENST00000376925.8	NP_000090.1
CST3	NM_001288614.2	c.290C>T	p.Thr97Ile	missense_variant	2/4		NP_001275543.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CST3	ENST00000376925.8	c.290C>T	p.Thr97Ile	missense_variant	2/3	1	NM_000099.4	ENSP00000366124	P1
CST3	ENST00000398411.5	c.290C>T	p.Thr97Ile	missense_variant	2/4	1		ENSP00000381448	P1
CST3	ENST00000398409.1	c.290C>T	p.Thr97Ile	missense_variant	3/4	3		ENSP00000381446	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000796 AC: 2 AN: 251358 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135866

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 SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000176

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000349 AC: 51 AN: 1461616 Hom.: 0 Cov.: 32 AF XY: 0.0000289 AC XY: 21 AN XY: 727120

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000459

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

EpiCase AF: 0.000109

EpiControl AF: 0.0000593

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Aug 17, 2021

The c.290C>T (p.T97I) alteration is located in exon 2 (coding exon 2) of the CST3 gene. This alteration results from a C to T substitution at nucleotide position 290, causing the threonine (T) at amino acid position 97 to be replaced by an isoleucine (I). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.21	D
BayesDel_noAF	Uncertain	0.080
CADD	Pathogenic	26
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.46	T;T;T
Eigen	Uncertain	0.57
Eigen_PC	Uncertain	0.36
FATHMM_MKL	Benign	0.73	D
LIST_S2	Uncertain	0.89	.;.;D
M_CAP	Benign	0.028	D
MetaRNN	Pathogenic	0.99	D;D;D
MetaSVM	Uncertain	-0.24	T
MutationAssessor	Pathogenic	4.0	H;H;H
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.69	T
PROVEAN	Pathogenic	-5.7	D;D;D
REVEL	Uncertain	0.46
Sift	Uncertain	0.0010	D;D;D
Sift4G	Pathogenic	0.0010	D;D;D
Polyphen		1.0	D;D;D
Vest4		0.88
MutPred		0.91		Loss of disorder (P = 0.0524);Loss of disorder (P = 0.0524);Loss of disorder (P = 0.0524);
MVP		0.65
MPC		1.3
ClinPred		1.0	D
GERP RS		4.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.97
gMVP		0.88

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: rs1355608117; hg19: chr20-23615958;