21-43774225-G-A

Position:

chr21-43774225-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 4P and 1B. PM1PM2BP4

The NM_000100.4(CSTB):c.274C>T(p.His92Tyr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000186 in 1,614,104 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/20 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 33)

Exomes 𝑓: 0.0000014 ( 0 hom. )

Consequence

CSTB
NM_000100.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:2

Conservation

PhyloP100: 2.01

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 links:

CSTB (HGNC:):

CSTB links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 3 ACMG points.

PM1

In a chain Cystatin-B (size 97) in uniprot entity CYTB_HUMAN there are 6 pathogenic changes around while only 2 benign (75%) in NM_000100.4

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (MetaRNN=0.37126404).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CSTB	NM_000100.4 linkuse as main transcript	c.274C>T	p.His92Tyr	missense_variant	3/3	ENST00000291568.7	NP_000091.1	P04080Q76LA1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CSTB	ENST00000291568.7 linkuse as main transcript	c.274C>T	p.His92Tyr	missense_variant	3/3	1	NM_000100.4	ENSP00000291568.6		P04080

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152218

Hom.:

Cov.:

show subpopulations

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

GnomAD3 exomes

AF:

0.00000795

AC:

AN:

251472

Hom.:

AF XY:

0.00000736

AC XY:

AN XY:

135922

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000578

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000137

AC:

AN:

1461886

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

727244

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.0000447

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152218

Hom.:

Cov.:

AF XY:

0.0000134

AC XY:

AN XY:

74370

show subpopulations

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:2

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not provided

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Jun 03, 2013

p.His92Tyr (CAT>TAT): c.274 C>T in exon 3 of the CSTB gene (NM_000100.2). The His92Tyr missense change has not been published as a mutation, nor has it been reported as a benign polymorphism to our knowledge. It was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. This substitution alters a poorly conserved position in the protein. However, it results in the His92Tyr amino acid substitution, which is a non-conservative change since a positively charged Histidine residue is replaced by an uncharged Tyrosine residue, and multiple in silico algorithms predict His92Tyr may be damaging to protein structure/function. Therefore, based on the currently available information, it is unclear whether His92Tyr is a disease-causing mutation or a rare benign variant. The variant is found in CHILD-EPI panel(s). -

Progressive myoclonic epilepsy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Apr 16, 2022

This sequence change replaces histidine, which is basic and polar, with tyrosine, which is neutral and polar, at codon 92 of the CSTB protein (p.His92Tyr). This variant is present in population databases (rs796052393, gnomAD 0.009%). This variant has not been reported in the literature in individuals affected with CSTB-related conditions. ClinVar contains an entry for this variant (Variation ID: 205329). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.10

BayesDel_addAF

Benign

-0.20

BayesDel_noAF

Benign

-0.35

CADD

Benign

DANN

Uncertain

0.98

DEOGEN2

Benign

0.27

Eigen

Benign

-0.30

Eigen_PC

Benign

-0.48

FATHMM_MKL

Benign

0.34

LIST_S2

Benign

0.78

M_CAP

Benign

0.057

MetaRNN

Benign

0.37

MetaSVM

Benign

-0.51

PrimateAI

Uncertain

0.56

PROVEAN

Uncertain

-4.0

REVEL

Benign

0.17

Sift

Uncertain

0.025

Sift4G

Uncertain

0.021

Polyphen

1.0

Vest4

0.40

MutPred

0.32

Loss of methylation at K91 (P = 0.0431);

MVP

0.69

MPC

0.56

ClinPred

0.70

GERP RS

0.97

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.1

Varity_R

0.43

gMVP

0.18

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over