12-20855143-G-GT

Variant names:

• chr12-20855143-G-GT
• rs748195197
• NM_019844.4:c.203dupT

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_019844.4(SLCO1B3):​c.203dupT​(p.Leu68PhefsTer3) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000995 in 1,608,482 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000096 (0 hom.)
• Consequence: SLCO1B3 NM_019844.4 frameshift
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -1.53

Genes affected

SLCO1B3 (HGNC:10961): (solute carrier organic anion transporter family member 1B3) This gene encodes a liver-specific member of the organic anion transporter family. The encoded protein is a transmembrane receptor that mediates the sodium-independent uptake of endogenous and xenobiotic compounds and plays a critical role in bile acid and bilirubin transport. Mutations in this gene are a cause of Rotor type hyperbilirubinemia. Alternative splicing of this gene and the use of alternative promoters results in transcript variants encoding different isoforms that differ in their tissue specificity. [provided by RefSeq, Mar 2017]

SLCO1B3-SLCO1B7 (HGNC:54403): (SLCO1B3-SLCO1B7 readthrough) This locus represents naturally occurring readthrough transcription between the neighboring SLCO1B3 (solute carrier organic anion transporter family member 1B3) and SLCO1B7 (solute carrier organic anion transporter family member 1B7 (putative)) genes on chromosome 12. The readthrough transcript encodes a protein that shares sequence identity with both the upstream and downstream genes. [provided by RefSeq, Jun 2019]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SLCO1B3	NM_019844.4	c.203dupT	p.Leu68PhefsTer3	frameshift_variant	Exon 4 of 16	ENST00000381545.8	NP_062818.1
SLCO1B3-SLCO1B7	NM_001371097.1	c.203dupT	p.Leu68PhefsTer3	frameshift_variant	Exon 2 of 16		NP_001358026.1
SLCO1B3	NM_001349920.2	c.119dupT	p.Leu40PhefsTer3	frameshift_variant	Exon 2 of 14		NP_001336849.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SLCO1B3	ENST00000381545.8	c.203dupT	p.Leu68PhefsTer3	frameshift_variant	Exon 4 of 16	2	NM_019844.4	ENSP00000370956.4
SLCO1B3-SLCO1B7	ENST00000540229.1	c.203dupT	p.Leu68PhefsTer3	frameshift_variant	Exon 2 of 16	2		ENSP00000441269.1

Frequencies

GnomAD3 genomes AF: 0.0000132 AC: 2 AN: 151930 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.000288

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.00000814 AC: 2 AN: 245810 Hom.: 0 AF XY: 0.00000752 AC XY: 1 AN XY: 132896

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.000203

Gnomad EAS exome AF: 0.00

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: 0.00000961 AC: 14 AN: 1456552 Hom.: 0 Cov.: 30 AF XY: 0.00000966 AC XY: 7 AN XY: 724620

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.000385

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.0000498

GnomAD4 genome AF: 0.0000132 AC: 2 AN: 151930 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74178

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.000288

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000434 Hom.: 0

Bravo AF: 0.0000113

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Rotor syndrome Uncertain:1

Oct 02, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The SLCO1B1 c.203dupT (p.Leu68PhefsTer3) variant results in a frameshift, and is predicted to cause an elongation of the protein. A literature search was performed for the gene, cDNA change, and amino acid change. No publications were found based on this search. The variant is reported at a frequency of 0.000208 in the Ashkenazi Jewish population from the Genome Aggregation Database, however this is based on two alleles so the variant is presumed to be rare. Based on the variant frequency, disease prevalence, disease penetrance, and inheritance mode, this variant could not be ruled out of causing disease. Due to the potential impact of frameshift variants and the lack of clarifying evidence, this variant is classified as a variant of unknown significance but suspicious for pathogenicity for Rotor syndrome. Note: bi-allelic variants in both the SLCO1B1 and SLCO1B3 genes combined have been shown to cause Rotor syndrome. For an individual to be affected with Rotor syndrome, they must carry a pathogenic variant in both copies of the SLCO1B1 gene and in both copies of the SLCO1B3 gene. This variant was observed by ICSL as part of a predisposition screen in an ostensibly healthy population. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.050		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: rs748195197; hg19: chr12-21008077;