chr7-117559629-G-T
Variant summary
Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1PM2PP3_StrongPP5_Very_Strong
The NM_000492.4(CFTR):c.1558G>T(p.Val520Phe) variant causes a missense change. The variant allele was found at a frequency of 0.0000267 in 1,613,014 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 Pathogenic (★★★).
Frequency
Consequence
NM_000492.4 missense
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Pathogenic. Variant got 16 ACMG points.
Transcripts
RefSeq
Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | MANE | Protein | UniProt |
---|---|---|---|---|---|---|---|---|
CFTR | NM_000492.4 | c.1558G>T | p.Val520Phe | missense_variant | Exon 11 of 27 | ENST00000003084.11 | NP_000483.3 | |
CFTR-AS1 | NR_149084.1 | n.221+1104C>A | intron_variant | Intron 2 of 2 |
Ensembl
Frequencies
GnomAD3 genomes AF: 0.00000658 AC: 1AN: 152036Hom.: 0 Cov.: 32
GnomAD3 exomes AF: 0.00000398 AC: 1AN: 251102Hom.: 0 AF XY: 0.00 AC XY: 0AN XY: 135756
GnomAD4 exome AF: 0.0000287 AC: 42AN: 1460978Hom.: 0 Cov.: 30 AF XY: 0.0000275 AC XY: 20AN XY: 726852
GnomAD4 genome AF: 0.00000658 AC: 1AN: 152036Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0AN XY: 74260
ClinVar
Submissions by phenotype
Cystic fibrosis Pathogenic:7
This sequence change replaces valine, which is neutral and non-polar, with phenylalanine, which is neutral and non-polar, at codon 520 of the CFTR protein (p.Val520Phe). This variant is present in population databases (rs77646904, gnomAD 0.002%). This missense change has been observed in individuals with cystic fibrosis (PMID: 1284466, 1376016, 22658665, 23974870). ClinVar contains an entry for this variant (Variation ID: 7150). 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 expected to disrupt CFTR protein function with a positive predictive value of 80%. Experimental studies have shown that this missense change affects CFTR function (PMID: 23891399, 23974870). For these reasons, this variant has been classified as Pathogenic. -
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The c.1558G>T (p.V520F) alteration is located in exon 11 (coding exon 11) of the CFTR gene. This alteration results from a G to T substitution at nucleotide position 1558, causing the valine (V) at amino acid position 520 to be replaced by a phenylalanine (F). Based on data from gnomAD, the T allele has an overall frequency of 0.001% (2/282480) total alleles studied. The highest observed frequency was 0.002% (2/128982) of European (non-Finnish) alleles. This variant was first identified in 3 out of 42 cystic fibrosis chromosomes (Jones, 1992). Additionally, this variant is associated with elevated sweat chloride levels and pancreatic insufficiency (Sosnay, 2013). This amino acid position is well conserved in available vertebrate species. Functional studies found that this mutation results in very low levels of mature CFTR protein and little to no chloride conductance (Sosnay, 2013; Van Goor, 2014; Hirtz, 2004). This alteration is predicted to be deleterious by in silico analysis. Based on the available evidence, this alteration is classified as pathogenic. -
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The CFTR c.1558G>T; p.Val520Phe variant (rs77646904, ClinVar Variation ID: 7150) is reported in over 100 cystic fibrosis individuals with an average sweat chloride of 101mEq/L and 92% of these individuals reported to be pancreatic insufficient (see CFTR2 database). This variant is only found on two alleles in the Genome Aggregation Database (v2.1.1), indicating it is not a common polymorphism. Computational analyses predict that this variant is deleterious (REVEL: 0.871). In support of these predictions, functional analyses demonstrate an effect of this variant on CFTR quantity and function (see CFTR2 database, Avramescu 2017, Van Goor 2014). Based on available information, this variant is considered to be pathogenic. References: Link to CFTR2 database: https://cftr2.org/ Avramescu RG et al. Mutation-specific downregulation of CFTR2 variants by gating potentiators. Hum Mol Genet. 2017 Dec 15;26(24):4873-4885. PMID: 29040544. Van Goor F et al. Effect of ivacaftor on CFTR forms with missense mutations associated with defects in protein processing or function. J Cyst Fibros. 2014 Jan;13(1):29-36. PMID: 23891399. -
NM_000492.3(CFTR):c.1558G>T(V520F) is classified as pathogenic in the context of cystic fibrosis and is associated with classic disease. Sources cited for classification include the following: PMID 1284466, 23974870 and 18456578. Classification of NM_000492.3(CFTR):c.1558G>T(V520F) is based on the following criteria: This is a well-established pathogenic variant in the literature that has been observed more frequently in patients with clinical diagnoses than in healthy populations. Please note: this variant was assessed in the context of healthy population screening. -
CFTR-related disorder Pathogenic:2
The CFTR c.1558G>T variant is predicted to result in the amino acid substitution p.Val520Phe. This variant has been reported in multiple individuals with cystic fibrosis (see for example, Jones et al 1992. PubMed ID: 1284466; Van Goor et al 2013. PubMed ID: 23891399). An in vitro experimental study suggests this variant diminishes expression of the CFTR protein (Avramescu et al 2017. PubMed ID: 29040544). This variant is reported in 0.0016% of alleles in individuals of European (Non-Finnish) descent in gnomAD (http://gnomad.broadinstitute.org/variant/7-117199683-G-T) and has been interpreted by multiple laboratories in ClinVar as pathogenic (https://www.ncbi.nlm.nih.gov/clinvar/variation/7150/). This variant is interpreted as pathogenic. -
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not provided Pathogenic:2
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not specified Pathogenic:1
Variant summary: The CFTR c.1558G>T (p.Val520Phe) variant located in the P-loop containing nucleoside triphosphate hydrolase (via InterPro) involves the alteration of a conserved nucleotide and 5/5 in silico tools predict a damaging outcome for this variant. This variant was found in 2/276844 control chromosomes at a frequency of 0.0000072, which does not exceed the estimated maximal expected allele frequency of a pathogenic CFTR variant (0.0129603). The variant of interest has been reported in multiple affected CF pts (Sosnay_2013). A function study, Van Goor_2013, found the variant to significantly affect CFTR processing and Cl- transport. In addition, multiple clinical diagnostic laboratories/reputable databases classified this variant as pathogenic. Taken together, this variant is classified as pathogenic. -
Cystic fibrosis;C0403814:Congenital bilateral aplasia of vas deferens from CFTR mutation Pathogenic:1
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Bronchiectasis with or without elevated sweat chloride 1 Pathogenic:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at