20-23750775-G-T

Variant names:

• chr20-23750775-G-T
• rs2070856
• NM_001898.3:c.92C>A

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_001898.3(CST1):​c.92C>A​(p.Pro31Gln) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000248 in 1,613,884 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/22 in silico tools predict a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency:
  • Genomes: 𝑓 0.000020 (0 hom., cov: 31)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: CST1 NM_001898.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: -1.02
• Publications: 21 publications found

Genes affected

CST1 (HGNC:2473): (cystatin SN) 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 a cysteine proteinase inhibitor found in saliva, tears, urine, and seminal fluid. [provided by RefSeq, Jul 2008]

CST1 Gene-Disease associations (from GenCC):

• male infertility with azoospermia or oligozoospermia due to single gene mutation

  Inheritance: AR Classification: LIMITED Submitted by: King Faisal Specialist Hospital and Research Center

ACMG classification

Our verdict: Uncertain_significance. The variant received 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.13279557).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CST1	NM_001898.3	c.92C>A	p.Pro31Gln	missense_variant	Exon 1 of 3	ENST00000304749.7	NP_001889.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CST1	ENST00000304749.7	c.92C>A	p.Pro31Gln	missense_variant	Exon 1 of 3	1	NM_001898.3	ENSP00000305731.2
CST1	ENST00000398402.1	c.92C>A	p.Pro31Gln	missense_variant	Exon 2 of 4	5		ENSP00000381439.1

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152038 Hom.: 0 Cov.: 31

Gnomad AFR AF: 0.0000725

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

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 AF: 6.84e-7 AC: 1 AN: 1461846 Hom.: 0 Cov.: 33 AF XY: 0.00000138 AC XY: 1 AN XY: 727220

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44718

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26134

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86254

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53416

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111982

Other (OTH) AF: 0.0000166 AC: 1 AN: 60396

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152038 Hom.: 0 Cov.: 31 AF XY: 0.0000135 AC XY: 1 AN XY: 74260

African (AFR) AF: 0.0000725 AC: 3 AN: 41394

American (AMR) AF: 0.00 AC: 0 AN: 15272

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5150

South Asian (SAS) AF: 0.00 AC: 0 AN: 4822

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10612

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 314

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68000

Other (OTH) AF: 0.00 AC: 0 AN: 2090

Alfa AF: 0.00 Hom.: 6060

ExAC AF: 0.00000824 AC: 1

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.22
BayesDel_addAF	Benign	-0.36	T
BayesDel_noAF	Benign	-0.75
CADD	Benign	0.011
DANN	Benign	0.34
DEOGEN2	Benign	0.061	T;T
Eigen	Benign	-1.7
Eigen_PC	Benign	-1.8
FATHMM_MKL	Benign	0.0038	N
LIST_S2	Benign	0.0	.;T
M_CAP	Benign	0.0013	T
MetaRNN	Benign	0.13	T;T
MetaSVM	Benign	-0.96	T
MutationAssessor	Benign	0.0	N;N
PhyloP100		-1.0
PrimateAI	Benign	0.34	T
PROVEAN	Benign	-0.61	N;N
REVEL	Benign	0.034
Sift	Benign	0.17	T;T
Sift4G	Benign	0.61	T;T
Vest4		0.13
ClinPred		0.042	T
GERP RS		-2.9
PromoterAI		-0.00070	Neutral
Varity_R		0.060
gMVP		0.28
Mutation Taster		=99/1	polymorphism

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

Other links and lift over

dbSNP: rs2070856; hg19: chr20-23731412;