4-76161720-C-T

Position:

• chr4-76161720-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 4P and 1B. PM1 PM2 BP4

The NM_005506.4(SCARB2):​c.1430G>A​(p.Arg477Gln) variant causes a missense change. The variant allele was found at a frequency of 0.00000821 in 1,461,862 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 Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000082 (0 hom.)
• Consequence: SCARB2 NM_005506.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.77

Genes affected

SCARB2 (HGNC:1665): (scavenger receptor class B member 2) The protein encoded by this gene is a type III glycoprotein that is located primarily in limiting membranes of lysosomes and endosomes. Earlier studies in mice and rat suggested that this protein may participate in membrane transportation and the reorganization of endosomal/lysosomal compartment. The protein deficiency in mice was reported to impair cell membrane transport processes and cause pelvic junction obstruction, deafness, and peripheral neuropathy. Further studies in human showed that this protein is a ubiquitously expressed protein and that it is involved in the pathogenesis of HFMD (hand, foot, and mouth disease) caused by enterovirus-71 and possibly by coxsackievirus A16. Mutations in this gene caused an autosomal recessive progressive myoclonic epilepsy-4 (EPM4), also known as action myoclonus-renal failure syndrome (AMRF). Alternatively spliced transcript variants encoding different isoforms have been found for this gene.[provided by RefSeq, Feb 2011]

(HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM1: In a mutagenesis_site Normal targeting of the protein to lysosomes. (size 0) in uniprot entity SCRB2_HUMAN
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.3017804).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SCARB2	NM_005506.4	c.1430G>A	p.Arg477Gln	missense_variant	12/12	ENST00000264896.8
SCARB2	NM_001204255.2	c.1001G>A	p.Arg334Gln	missense_variant	9/9
SCARB2	XM_047416429.1	c.956G>A	p.Arg319Gln	missense_variant	12/12
SCARB2	XM_047416430.1	c.956G>A	p.Arg319Gln	missense_variant	12/12

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SCARB2	ENST00000264896.8	c.1430G>A	p.Arg477Gln	missense_variant	12/12	1	NM_005506.4	P4
	ENST00000651366.1	n.102+12454C>T		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000399 AC: 1 AN: 250882 Hom.: 0 AF XY: 0.00000737 AC XY: 1 AN XY: 135654

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 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: 0.00000821 AC: 12 AN: 1461862 Hom.: 0 Cov.: 30 AF XY: 0.00000963 AC XY: 7 AN XY: 727236

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000252

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000989

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000329 Hom.: 0

Bravo AF: 0.0000151

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Progressive myoclonic epilepsy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 27, 2021

This sequence change replaces arginine with glutamine at codon 477 of the SCARB2 protein (p.Arg477Gln). The arginine residue is moderately conserved and there is a small physicochemical difference between arginine and glutamine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals affected with SCARB2-related conditions. 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: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). 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	0.15
BayesDel_addAF	Uncertain	0.012	T
BayesDel_noAF	Uncertain	-0.050
CADD	Pathogenic	26
DANN	Pathogenic	1.0
DEOGEN2	Benign	0.19	T;.;.;.;.;.
Eigen	Uncertain	0.50
Eigen_PC	Uncertain	0.54
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.94	D;D;D;D;D;D
M_CAP	Uncertain	0.10	D
MetaRNN	Benign	0.30	T;T;T;T;T;T
MetaSVM	Uncertain	0.56	D
MutationAssessor	Benign	2.0	M;.;.;.;.;.
MutationTaster	Benign	0.94	D;D
PrimateAI	Uncertain	0.55	T
PROVEAN	Benign	-0.80	N;.;.;.;.;N
REVEL	Uncertain	0.34
Sift	Uncertain	0.012	D;.;.;.;.;D
Sift4G	Pathogenic	0.0	D;.;.;.;.;D
Polyphen		1.0	D;.;.;.;.;.
Vest4		0.37
MutPred		0.22		Loss of glycosylation at T478 (P = 0.0528);.;.;.;.;.;
MVP		0.86
MPC		0.92
ClinPred		0.92	D
GERP RS		5.2
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.13
gMVP		0.58

Splicing

Name	Calibrated prediction	Score	Prediction
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: rs1480481844; hg19: chr4-77082873; COSMIC: COSV53668563;