20-23685967-C-A

Variant names:

• chr20-23685967-C-A
• rs565550102
• NM_001899.3:c.353G>T

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_001899.3(CST4):​c.353G>T​(p.Cys118Phe) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000657 in 152,108 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
• Consequence: CST4 NM_001899.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.28

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 Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.976

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CST4	NM_001899.3	c.353G>T	p.Cys118Phe	missense_variant	Exon 3 of 3	ENST00000217423.4	NP_001890.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CST4	ENST00000217423.4	c.353G>T	p.Cys118Phe	missense_variant	Exon 3 of 3	1	NM_001899.3	ENSP00000217423.3

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152108 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000654

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 31

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152108 Hom.: 0 Cov.: 33 AF XY: 0.0000135 AC XY: 1 AN XY: 74290

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.0000654

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Jan 18, 2025

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.353G>T (p.C118F) alteration is located in exon 3 (coding exon 3) of the CST4 gene. This alteration results from a G to T substitution at nucleotide position 353, causing the cysteine (C) at amino acid position 118 to be replaced by a phenylalanine (F). 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	0.80
BayesDel_addAF	Uncertain	0.029	T
BayesDel_noAF	Benign	-0.20
CADD	Uncertain	24
DANN	Benign	0.97
DEOGEN2	Benign	0.15	T
Eigen	Benign	0.16
Eigen_PC	Benign	-0.14
FATHMM_MKL	Benign	0.28	N
LIST_S2	Benign	0.70	T
M_CAP	Benign	0.0016	T
MetaRNN	Pathogenic	0.98	D
MetaSVM	Benign	-0.88	T
MutationAssessor	Pathogenic	3.7	H
PrimateAI	Uncertain	0.51	T
PROVEAN	Pathogenic	-9.9	D
REVEL	Uncertain	0.29
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.77
MutPred		0.91		Loss of ubiquitination at K115 (P = 0.0863);
MVP		0.30
MPC		0.014
ClinPred		1.0	D
GERP RS		1.9
Varity_R		0.88
gMVP		0.61

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: rs565550102; hg19: chr20-23666604;