Genetic Variant CSTB:p.Lys91Lys (chr21-43774226-C-T) – ACMG Classification: Likely_benign (-5 pts)

Variant summary

Our verdict is Likely benign. The variant received -5 ACMG points: 2P and 7B. PM2BP4_StrongBP6_ModerateBP7

The NM_000100.4(CSTB):c.273G>A(p.Lys91Lys) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,890 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★).

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 0.0000014 ( 0 hom. )

Consequence

CSTB
NM_000100.4 synonymous

Scores

Clinical Significance

Likely benign criteria provided, single submitter B:1

Conservation

PhyloP100: 0.777

Publications

0 publications found

Variant links:

Genes affected

CSTB (HGNC:2482): (cystatin B) 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 kininogens. This gene encodes a stefin that functions as an intracellular thiol protease inhibitor. The protein is able to form a dimer stabilized by noncovalent forces, inhibiting papain and cathepsins l, h and b. The protein is thought to play a role in protecting against the proteases leaking from lysosomes. Evidence indicates that mutations in this gene are responsible for the primary defects in patients with progressive myoclonic epilepsy (EPM1). One type of mutation responsible for EPM1 is the expansion in the promoter region of this gene of a CCCCGCCCCGCG repeat from 2-3 copies to 30-78 copies. [provided by RefSeq, Jul 2016]

CSTB Gene-Disease associations (from GenCC):

Unverricht-Lundborg syndrome
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: ClinGen, G2P, Orphanet, Labcorp Genetics (formerly Invitae)
keratolytic winter erythema
Inheritance: AD Classification: MODERATE Submitted by: PanelApp Australia
genetic developmental and epileptic encephalopathy
Inheritance: AR Classification: MODERATE Submitted by: ClinGen
autosomal recessive hypohidrotic ectodermal dysplasia
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

CSTB links:

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ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -5 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.78).

BP6

Variant 21-43774226-C-T is Benign according to our data. Variant chr21-43774226-C-T is described in ClinVar as [Likely_benign]. Clinvar id is 1095761.Status of the report is criteria_provided_single_submitter, 1 stars.

BP7

Synonymous conserved (PhyloP=0.777 with no splicing effect.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CSTB	NM_000100.4 link	c.273G>A	p.Lys91Lys	synonymous_variant	Exon 3 of 3	ENST00000291568.7	NP_000091.1	P04080Q76LA1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
CSTB	ENST00000291568.7 link	c.273G>A	p.Lys91Lys	synonymous_variant	Exon 3 of 3	1	NM_000100.4	ENSP00000291568.6	P04080
CSTB	ENST00000639959.1 link	c.138G>A	p.Lys46Lys	synonymous_variant	Exon 2 of 2	5		ENSP00000492123.1	A0A1W2PQG6
CSTB	ENST00000675996.1 link	n.698G>A		non_coding_transcript_exon_variant	Exon 3 of 3
CSTB	ENST00000640406.1 link	c.*348G>A		3_prime_UTR_variant	Exon 2 of 2	2		ENSP00000492672.1	A0A1W2PS52

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

0.00000137

AC:

AN:

1461890

Hom.:

Cov.:

AF XY:

0.00000275

AC XY:

AN XY:

727248

show subpopulations

African (AFR)

AF:

0.0000597

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53418

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1112010

Other (OTH)

AF:

0.00

AC:

AN:

60396

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.425

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Significance: Likely benign

Submissions summary: Benign:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Progressive myoclonic epilepsy

Benign:1

Nov 01, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.78

CADD

Benign

2.0

(source)

DANN

Benign

0.59

PhyloP100

0.78

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over