rs121909100
Variant summary
Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PP2PP3_ModeratePP5_Very_Strong
The NM_001374385.1(ATP8B1):c.1982T>C(p.Ile661Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000159 in 1,613,520 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★).
Frequency
Consequence
NM_001374385.1 missense
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Pathogenic. Variant got 11 ACMG points.
Transcripts
RefSeq
Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | MANE | Protein | UniProt |
---|---|---|---|---|---|---|---|---|
ATP8B1 | NM_001374385.1 | c.1982T>C | p.Ile661Thr | missense_variant | Exon 18 of 28 | ENST00000648908.2 | NP_001361314.1 |
Ensembl
Frequencies
GnomAD3 genomes AF: 0.0000986 AC: 15AN: 152130Hom.: 0 Cov.: 33
GnomAD3 exomes AF: 0.0000956 AC: 24AN: 251022Hom.: 0 AF XY: 0.000111 AC XY: 15AN XY: 135726
GnomAD4 exome AF: 0.000166 AC: 242AN: 1461390Hom.: 0 Cov.: 30 AF XY: 0.000176 AC XY: 128AN XY: 727018
GnomAD4 genome AF: 0.0000986 AC: 15AN: 152130Hom.: 0 Cov.: 33 AF XY: 0.0000673 AC XY: 5AN XY: 74324
ClinVar
Submissions by phenotype
not provided Pathogenic:6
This sequence change replaces isoleucine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 661 of the ATP8B1 protein (p.Ile661Thr). This variant is present in population databases (rs121909100, gnomAD 0.02%). This missense change has been observed in individuals with benign recurrent intrahepatic cholestasis and/or progressive familial intrahepatic cholestasis (PMID: 9500542, 9918928, 15239083, 20232290, 33666275, 34016879). ClinVar contains an entry for this variant (Variation ID: 7267). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt ATP8B1 protein function with a negative predictive value of 80%. Experimental studies have shown that this missense change affects ATP8B1 function (PMID: 19731236, 19918981). For these reasons, this variant has been classified as Pathogenic. -
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Progressive familial intrahepatic cholestasis type 1 Pathogenic:3Other:1
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At least 1 copy of this variant is found in most persons of European descent -
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Across a selection of available literature, the ATP8B1 c.1982T>C (p.Ile661Thr) variant has been reported in a homozygous state in 25 probands, in a compound heterozygous state in eight probands and in a heterozygous state in nine probands (Bull et al. 1998; Tygstrup et al. 1999; Klomp et al. 2004). The clinical presentation of many probands with this variant were described as having benign recurrent intrahepatic cholestatis, but some were described to have progressive disease. This disease has been noted to have reduced penetrance, and five individuals homozygous for the p.Ile661Thr variant were asymptomatic (Klomp et al. 2004). The p.Ile661Thr variant was absent from 289 controls and is reported at a frequency of 0.000158 in the European (non-Finnish) population of the Genome Aggregation Database. Functional studies to determine the effect of the p.Ile661Thr variant in cell lines document overall reduced protein expression compared to wild type (Folmer et al. 2009). Further investigation revealed the p.Ile661Thr variant to result in protein misfolding which was rescued by chemical chaperones such as 4-BPA (van der Velden et al. 2010; van der Woerd et al. 2016). Based on the collective evidence, the p.Ile661Thr variant is classified as pathogenic for familial intrahepatic cholestasis. This variant was observed by ICSL as part of a predisposition screen in an ostensibly healthy population. -
Benign recurrent intrahepatic cholestasis type 1 Pathogenic:3
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ATP8B1-related disorder Pathogenic:1
The ATP8B1 c.1982T>C variant is predicted to result in the amino acid substitution p.Ile661Thr. This variant has been reported to be one of the most common causative variants responsible for benign recurrent intrahepatic cholestasis (Bull et al. 1998. PubMed ID: 9500542; Folmer et al. 2009. PubMed ID: 19731236; van der Velden et al. 2010. PubMed ID: 19918981). This variant is reported in 0.016% of alleles in individuals of European (Non-Finnish) descent in gnomAD. This variant is interpreted as pathogenic. -
Progressive familial intrahepatic cholestasis Pathogenic:1
Variant summary: ATP8B1 c.1982T>C (p.Ile661Thr) results in a non-conservative amino acid change in the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 9.6e-05 in 251022 control chromosomes. This frequency is not significantly higher than estimated for a pathogenic variant in ATP8B1 causing Familial Intrahepatic Cholestasis (9.6e-05 vs 0.0022), allowing no conclusion about variant significance. c.1982T>C has been reported in the literature as a homozygous or compound heterozygous genotype in multiple individuals affected with Familial Intrahepatic Cholestasis (example, PMID: 19731236, 15239083, 9918928, 33666275). These data indicate that the variant is very likely to be associated with disease. At least one publication reports experimental evidence evaluating an impact on protein function (example, PMID: 19731236). The most pronounced variant effect results in decreased protein stability/overall reduced protein expression compared to wild type. Five clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation (Pathogenic, n=4). Based on the evidence outlined above, the variant was classified as pathogenic. -
Cholestasis, intrahepatic, of pregnancy, 1;C4551898:Progressive familial intrahepatic cholestasis type 1;C4551899:Benign recurrent intrahepatic cholestasis type 1 Pathogenic:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at