21-43774296-C-T

Variant names:

• chr21-43774296-C-T
• rs757707761
• NM_000100.4:c.203G>A

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 0P and 1B. BP4

The NM_000100.4(CSTB):​c.203G>A​(p.Arg68Gln) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000889 in 1,461,848 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/21 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 variant affecting the same amino acid position, but resulting in a different missense (i.e. R68P) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000089 (0 hom.)
• Consequence: CSTB NM_000100.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 1.96
• Publications: 0 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: 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

ACMG classification

Our verdict: Likely_benign. The variant received -1 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.3323329).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CSTB	NM_000100.4	c.203G>A	p.Arg68Gln	missense_variant	Exon 3 of 3	ENST00000291568.7	NP_000091.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CSTB	ENST00000291568.7	c.203G>A	p.Arg68Gln	missense_variant	Exon 3 of 3	1	NM_000100.4	ENSP00000291568.6
CSTB	ENST00000639959.1	c.68G>A	p.Arg23Gln	missense_variant	Exon 2 of 2	5		ENSP00000492123.1
CSTB	ENST00000675996.1	n.628G>A		non_coding_transcript_exon_variant	Exon 3 of 3
CSTB	ENST00000640406.1	c.*278G>A		3_prime_UTR_variant	Exon 2 of 2	2		ENSP00000492672.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.0000119 AC: 3 AN: 251456 AF XY: 0.00000736

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000176

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000889 AC: 13 AN: 1461848 Hom.: 0 Cov.: 31 AF XY: 0.00000825 AC XY: 6 AN XY: 727218

African (AFR) AF: 0.0000299 AC: 1 AN: 33480

American (AMR) AF: 0.00 AC: 0 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: 53378

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000989 AC: 11 AN: 1112010

Other (OTH) AF: 0.0000166 AC: 1 AN: 60394

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 0

ExAC AF: 0.00000824 AC: 1

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.19
BayesDel_addAF	Benign	-0.25	T
BayesDel_noAF	Benign	-0.42
CADD	Benign	16
DANN	Uncertain	0.99
DEOGEN2	Benign	0.37	T
Eigen	Benign	-0.36
Eigen_PC	Benign	-0.39
FATHMM_MKL	Benign	0.55	D
LIST_S2	Benign	0.82	T
M_CAP	Benign	0.0086	T
MetaRNN	Benign	0.33	T
MetaSVM	Benign	-1.0	T
PhyloP100		2.0
PrimateAI	Uncertain	0.54	T
PROVEAN	Uncertain	-2.7	D
REVEL	Benign	0.14
Sift	Benign	0.070	T
Sift4G	Uncertain	0.055	T
Polyphen		0.47	P
Vest4		0.35
MutPred		0.63		Loss of sheet (P = 0.0817);
MVP		0.099
MPC		0.20
ClinPred		0.68	D
GERP RS		3.6
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.54
gMVP		0.62
Mutation Taster		=86/14	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: rs757707761; hg19: chr21-45194177;