4-76168400-T-TA

Position:

• chr4-76168400-T-TA

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_005506.4(SCARB2):​c.1187+2_1187+3insT variant causes a splice region, intron change. The variant allele was found at a frequency of 0.00000137 in 1,461,240 control chromosomes in the GnomAD database, with no homozygous occurrence. 1/1 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: SCARB2 NM_005506.4 splice_region, intron
• Clinical Significance: Uncertain significance criteria provided, single submitter P:2 U:1
• Conservation: PhyloP100: 6.84

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 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SCARB2	NM_005506.4	c.1187+2_1187+3insT		splice_region_variant, intron_variant		ENST00000264896.8	NP_005497.1
SCARB2	NM_001204255.2	c.758+2_758+3insT		splice_region_variant, intron_variant			NP_001191184.1
SCARB2	XM_047416429.1	c.713+2_713+3insT		splice_region_variant, intron_variant			XP_047272385.1
SCARB2	XM_047416430.1	c.713+2_713+3insT		splice_region_variant, intron_variant			XP_047272386.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SCARB2	ENST00000264896.8	c.1187+2_1187+3insT		splice_region_variant, intron_variant		1	NM_005506.4	ENSP00000264896	P4
	ENST00000651366.1	n.102+19135dup		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000796 AC: 2 AN: 251394 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135874

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

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: 0.0000176

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461240 Hom.: 0 Cov.: 30 AF XY: 0.00000138 AC XY: 1 AN XY: 726990

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

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: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Pathogenic:2 Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Action myoclonus-renal failure syndrome Pathogenic:2

Pathogenic, no assertion criteria provided	literature only	GeneReviews	Mar 05, 2015	- -
Pathogenic, no assertion criteria provided	literature only	OMIM	Jun 01, 2011	- -

Progressive myoclonic epilepsy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 29, 2022

This sequence change falls in intron 9 of the SCARB2 gene. It does not directly change the encoded amino acid sequence of the SCARB2 protein. It affects a nucleotide within the consensus splice site. This variant is present in population databases (rs727502783, gnomAD 0.002%). This variant has been observed in individual(s) with progressive myoclonic epilepsy without renal failure (PMID: 21670406). This variant is also known as c.1187+3insT. ClinVar contains an entry for this variant (Variation ID: 30259). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus 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

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.97		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.97		Position offset: 3

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs727502783; hg19: chr4-77089553;