rs6383

chr21-43774762-A-Gchr21-43774762-A-T

Variant summary

Our verdict is Benign. Variant got -20 ACMG points: 0P and 20B. BP4_Strong BP6_Very_Strong BS1 BS2

The NM_000100.4(CSTB):c.67-3T>C variant causes a splice region, splice polypyrimidine tract, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000834 in 1,610,974 control chromosomes in the GnomAD database, including 6 homozygotes. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Likely benign (★★).

• Frequency:
  • Genomes: 𝑓 0.0044 (4 hom., cov: 33)
  • Exomes 𝑓: 0.00046 (2 hom.)
• Consequence: CSTB NM_000100.4 splice_region, splice_polypyrimidine_tract, intron
• Scores: Splicing: ADA: 0.00009725
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:6
• Conservation: PhyloP100: 0.0380

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]

ACMG classification

Verdict is Benign. Variant got -20 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.77).
• BP6: Variant 21-43774762-A-G is Benign according to our data. Variant chr21-43774762-A-G is described in ClinVar as [Likely_benign]. Clinvar id is 137037.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BS1: Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.00443 (675/152330) while in subpopulation AFR AF= 0.0151 (627/41574). AF 95% confidence interval is 0.0141. There are 4 homozygotes in gnomad4. There are 309 alleles in male gnomad4 subpopulation. Median coverage is 33. This position pass quality control queck.
• BS2: High Homozygotes in GnomAd at 4 AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CSTB	NM_000100.4	c.67-3T>C		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant		ENST00000291568.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CSTB	ENST00000291568.7	c.67-3T>C		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant		1	NM_000100.4	P1
CSTB	ENST00000639959.1	c.36-432T>C		intron_variant		5
CSTB	ENST00000640406.1	c.67-3T>C		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant		2
CSTB	ENST00000675996.1	n.492-3T>C		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.00442 AC: 673 AN: 152212 Hom.: 4 Cov.: 33

Gnomad AFR AF: 0.0151

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00183

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00316

Gnomad NFE AF: 0.000103

Gnomad OTH AF: 0.00526

GnomAD3 exomes AF: 0.00111 AC: 278 AN: 251432 Hom.: 1 AF XY: 0.000802 AC XY: 109 AN XY: 135902

Gnomad AFR exome AF: 0.0145

Gnomad AMR exome AF: 0.000954

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: 0.0000527

Gnomad OTH exome AF: 0.000489

GnomAD4 exome AF: 0.000459 AC: 669 AN: 1458644 Hom.: 2 Cov.: 29 AF XY: 0.000409 AC XY: 297 AN XY: 725928

Gnomad4 AFR exome AF: 0.0152

Gnomad4 AMR exome AF: 0.00110

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000232

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000568

Gnomad4 OTH exome AF: 0.000730

GnomAD4 genome AF: 0.00443 AC: 675 AN: 152330 Hom.: 4 Cov.: 33 AF XY: 0.00415 AC XY: 309 AN XY: 74496

Gnomad4 AFR AF: 0.0151

Gnomad4 AMR AF: 0.00183

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.000207

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000103

Gnomad4 OTH AF: 0.00520

Alfa AF: 0.00145 Hom.: 0

Bravo AF: 0.00458

Asia WGS AF: 0.000289 AC: 1 AN: 3478

EpiCase AF: 0.000109

EpiControl AF: 0.000178

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Benign:3

Likely benign, criteria provided, single submitter	clinical testing	Genomic Diagnostic Laboratory, Division of Genomic Diagnostics, Children's Hospital of Philadelphia	Apr 14, 2015	- -
Benign, criteria provided, single submitter	clinical testing	GeneDx	Nov 21, 2013	This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -
Benign, criteria provided, single submitter	clinical testing	PreventionGenetics, part of Exact Sciences	-	- -

Inborn genetic diseases Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Dec 04, 2018

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Unverricht-Lundborg syndrome Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Progressive myoclonic epilepsy Benign:1

Benign, criteria provided, single submitter

clinical testing

Invitae

Jan 29, 2024

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.77
Cadd	Benign	3.5
Dann	Benign	0.77

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.000097
dbscSNV1_RF	Benign	0.0080
SpliceAI score (max)		0.020		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: rs6383; hg19: chr21-45194643;