20-23687159-G-A

Variant names:

• chr20-23687159-G-A
• rs745606281
• NM_001899.3:c.271C>T

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP3

The NM_001899.3(CST4):​c.271C>T​(p.Arg91Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000248 in 1,613,928 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: 𝑓 0.000033 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000024 (0 hom.)
• Consequence: CST4 NM_001899.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.289

Genes affected

CST4 (HGNC:2476): (cystatin S) 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. 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 a type 2 salivary cysteine peptidase inhibitor. The protein is an S-type cystatin, based on its high level of expression in saliva, tears and seminal plasma. The specific role in these fluids is unclear but antibacterial and antiviral activity is present, consistent with a protective function. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.78

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CST4	NM_001899.3	c.271C>T	p.Arg91Cys	missense_variant	Exon 2 of 3	ENST00000217423.4	NP_001890.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CST4	ENST00000217423.4	c.271C>T	p.Arg91Cys	missense_variant	Exon 2 of 3	1	NM_001899.3	ENSP00000217423.3

Frequencies

GnomAD3 genomes AF: 0.0000329 AC: 5 AN: 152048 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000242

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000192

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000294

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000199 AC: 5 AN: 251478 Hom.: 0 AF XY: 0.0000221 AC XY: 3 AN XY: 135912

Gnomad AFR exome AF: 0.0000615

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000109

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: 0.0000239 AC: 35 AN: 1461880 Hom.: 0 Cov.: 32 AF XY: 0.0000248 AC XY: 18 AN XY: 727246

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000101

Gnomad4 SAS exome AF: 0.0000348

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000198

Gnomad4 OTH exome AF: 0.0000331

GnomAD4 genome AF: 0.0000329 AC: 5 AN: 152048 Hom.: 0 Cov.: 32 AF XY: 0.0000539 AC XY: 4 AN XY: 74252

Gnomad4 AFR AF: 0.0000242

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000192

Gnomad4 SAS AF: 0.000207

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000294

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000227

ExAC AF: 0.0000330 AC: 4

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Jul 19, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.271C>T (p.R91C) alteration is located in exon 2 (coding exon 2) of the CST4 gene. This alteration results from a C to T substitution at nucleotide position 271, causing the arginine (R) at amino acid position 91 to be replaced by a cysteine (C). 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	Uncertain	0.49
BayesDel_addAF	Benign	-0.27	T
BayesDel_noAF	Benign	-0.39
CADD	Benign	21
DANN	Uncertain	0.99
DEOGEN2	Benign	0.26	T
Eigen	Benign	-0.12
Eigen_PC	Benign	-0.46
FATHMM_MKL	Benign	0.15	N
LIST_S2	Uncertain	0.93	D
M_CAP	Benign	0.00067	T
MetaRNN	Pathogenic	0.78	D
MetaSVM	Benign	-1.0	T
MutationAssessor	Pathogenic	3.5	H
PrimateAI	Uncertain	0.57	T
PROVEAN	Pathogenic	-6.8	D
REVEL	Benign	0.11
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.51
MutPred		0.83		Gain of ubiquitination at K96 (P = 0.0516);
MVP		0.26
MPC		0.015
ClinPred		0.87	D
GERP RS		-0.60
Varity_R		0.80
gMVP		0.31

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: rs745606281; hg19: chr20-23667796; COSMIC: COSV54149132;