chr21-43774306-C-G

Variant names:

• chr21-43774306-C-G
• rs570768038
• NM_000100.4:c.193G>C

Variant summary

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

The NM_000100.4(CSTB):​c.193G>C​(p.Val65Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000496 in 1,614,052 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V65I) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000048 (0 hom.)
• Consequence: CSTB NM_000100.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: -3.41
• Publications: 1 publications found

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: G2P, Orphanet, ClinGen, Labcorp Genetics (formerly Invitae)
• genetic developmental and epileptic encephalopathy

  Inheritance: AR Classification: MODERATE Submitted by: ClinGen
• autosomal recessive hypohidrotic ectodermal dysplasia

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

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=0.094080776).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000100.4. 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
	CSTB	NM_000100.4	MANE Select	c.193G>C	p.Val65Leu	missense	Exon 3 of 3	NP_000091.1	Q76LA1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CSTB	ENST00000291568.7	TSL:1 MANE Select	c.193G>C	p.Val65Leu	missense	Exon 3 of 3	ENSP00000291568.6	P04080
	CSTB	ENST00000896953.1		c.181G>C	p.Val61Leu	missense	Exon 3 of 3	ENSP00000567012.1
	CSTB	ENST00000937601.1		c.163G>C	p.Val55Leu	missense	Exon 3 of 3	ENSP00000607660.1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152218 Hom.: 0 Cov.: 33

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

GnomAD2 exomes AF: 0.0000119 AC: 3 AN: 251460 AF XY: 0.00000736

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000867

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 AF: 0.00000479 AC: 7 AN: 1461834 Hom.: 0 Cov.: 31 AF XY: 0.00000688 AC XY: 5 AN XY: 727218

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.0000894 AC: 4 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

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

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53372

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 0.00000270 AC: 3 AN: 1112004

Other (OTH) AF: 0.00 AC: 0 AN: 60394

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152218 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74362

African (AFR) AF: 0.00 AC: 0 AN: 41452

American (AMR) AF: 0.0000654 AC: 1 AN: 15284

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 5198

South Asian (SAS) AF: 0.00 AC: 0 AN: 4836

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

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

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68044

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

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000756

ClinVar

ClinVar submissions

Significance: Uncertain significance

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
-	1	-	not provided (1)
-	1	-	Progressive myoclonic epilepsy (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.10
BayesDel_addAF	Benign	-0.36	T
BayesDel_noAF	Benign	-0.55
CADD	Benign	0.12
DANN	Benign	0.68
DEOGEN2	Benign	0.16	T
Eigen	Benign	-1.1
Eigen_PC	Benign	-1.2
FATHMM_MKL	Benign	0.065	N
LIST_S2	Benign	0.76	T
M_CAP	Benign	0.0039	T
MetaRNN	Benign	0.094	T
MetaSVM	Benign	-1.0	T
PhyloP100		-3.4
PrimateAI	Uncertain	0.54	T
PROVEAN	Benign	-1.0	N
REVEL	Benign	0.031
Sift	Benign	0.46	T
Sift4G	Benign	0.47	T
Polyphen		0.054	B
Vest4		0.087
MutPred		0.37		Gain of relative solvent accessibility (P = 0.2629)
MVP		0.030
MPC		0.14
ClinPred		0.036	T
GERP RS		-2.3
Varity_R		0.23
gMVP		0.27
Mutation Taster		=87/13	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: rs570768038; hg19: chr21-45194187;