20-23440291-C-G

Variant names:

• chr20-23440291-C-G
• rs765909056
• NM_138283.1:c.24C>G

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_138283.1(CSTL1):​c.24C>G​(p.Asn8Lys) 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 152,148 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/21 in silico tools predict a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another nucleotide change resulting in the same amino acid substitution has been previously reported as Uncertain significance in ClinVar.

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
• Consequence: CSTL1 NM_138283.1 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: -0.554
• Publications: 1 publications found

Genes affected

CSTL1 (HGNC:15958): (cystatin like 1) 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 at the telomeric end of the cystatin locus and encodes a type 2 cystatin-like protein. The specific function of this protein has not been determined. [provided by RefSeq, Jul 2008]

ACMG classification

Our verdict: Likely_benign. The variant received -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.063719064).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_138283.1. 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
	CSTL1	NM_138283.1	MANE Select	c.24C>G	p.Asn8Lys	missense	Exon 2 of 4	NP_612140.1	Q9H114
	CSTL1	NR_170937.1		n.285C>G		non_coding_transcript_exon	Exon 2 of 5
	CSTL1	NR_170938.1		n.285C>G		non_coding_transcript_exon	Exon 2 of 5

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CSTL1	ENST00000347397.5	TSL:1 MANE Select	c.24C>G	p.Asn8Lys	missense	Exon 2 of 4	ENSP00000344907.1	Q9H114
	CSTL1	ENST00000246020.3	TSL:1	c.24C>G	p.Asn8Lys	missense	Exon 2 of 4	ENSP00000246020.2	Q9H114
	CSTL1	ENST00000472140.5	TSL:2	n.270C>G		non_coding_transcript_exon	Exon 2 of 3

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152148 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000241

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

GnomAD2 exomes AF: 0.00000398 AC: 1 AN: 251354 AF XY: 0.00

Gnomad AFR exome AF: 0.0000615

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.: 31

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152148 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74322

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

African (AFR) AF: 0.0000241 AC: 1 AN: 41426

American (AMR) AF: 0.00 AC: 0 AN: 15278

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 5182

South Asian (SAS) AF: 0.00 AC: 0 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10614

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68024

Other (OTH) AF: 0.00 AC: 0 AN: 2092

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000756

ExAC AF: 0.00000824 AC: 1

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.13
BayesDel_addAF	Benign	-0.50	T
BayesDel_noAF	Benign	-0.77
CADD	Benign	0.11
DANN	Benign	0.47
DEOGEN2	Benign	0.0022	T
Eigen	Benign	-1.2
Eigen_PC	Benign	-1.2
FATHMM_MKL	Benign	0.021	N
LIST_S2	Benign	0.22	T
M_CAP	Benign	0.0016	T
MetaRNN	Benign	0.064	T
MetaSVM	Benign	-0.94	T
PhyloP100		-0.55
PrimateAI	Benign	0.39	T
PROVEAN	Benign	-0.85	N
REVEL	Benign	0.033
Sift	Benign	0.033	D
Sift4G	Benign	0.56	T
Polyphen		0.0	B
Vest4		0.10
MutPred		0.52		Gain of ubiquitination at N8 (P = 0.0276)
MVP		0.048
MPC		0.062
ClinPred		0.021	T
GERP RS		0.015
Varity_R		0.069
gMVP		0.22
Mutation Taster		=99/1	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs765909056; hg19: chr20-23420928;