NM_000492.4:c.355A>G

Variant names:

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM1PM2

The NM_000492.4(CFTR):c.355A>G(p.Ile119Val) variant causes a missense change. The variant allele was found at a frequency of 0.000107 in 1,607,930 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★).

Frequency

Genomes: 𝑓 0.000039 ( 0 hom., cov: 32)

Exomes 𝑓: 0.00011 ( 0 hom. )

Consequence

CFTR
NM_000492.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:8

Conservation

PhyloP100: 5.25

Variant links:

Genes affected

CFTR (HGNC:1884): (CF transmembrane conductance regulator) This gene encodes a member of the ATP-binding cassette (ABC) transporter superfamily. The encoded protein functions as a chloride channel, making it unique among members of this protein family, and controls ion and water secretion and absorption in epithelial tissues. Channel activation is mediated by cycles of regulatory domain phosphorylation, ATP-binding by the nucleotide-binding domains, and ATP hydrolysis. Mutations in this gene cause cystic fibrosis, the most common lethal genetic disorder in populations of Northern European descent. The most frequently occurring mutation in cystic fibrosis, DeltaF508, results in impaired folding and trafficking of the encoded protein. Multiple pseudogenes have been identified in the human genome. [provided by RefSeq, Aug 2017]

CFTR links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 4 ACMG points.

PM1

In a topological_domain Extracellular (size 23) in uniprot entity CFTR_HUMAN there are 19 pathogenic changes around while only 0 benign (100%) in NM_000492.4

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CFTR	NM_000492.4 link	c.355A>G	p.Ile119Val	missense_variant	Exon 4 of 27	ENST00000003084.11	NP_000483.3	P13569-1A0A024R730

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CFTR	ENST00000003084.11 link	c.355A>G	p.Ile119Val	missense_variant	Exon 4 of 27	1	NM_000492.4	ENSP00000003084.6		P13569-1

Frequencies

GnomAD3 genomes

AF:

0.0000394

AC:

AN:

152192

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000588

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000279

AC:

AN:

250942

Hom.:

AF XY:

0.0000442

AC XY:

AN XY:

135600

show subpopulations

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:

0.0000617

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.000114

AC:

166

AN:

1455738

Hom.:

Cov.:

AF XY:

0.000105

AC XY:

AN XY:

724480

show subpopulations

Gnomad4 AFR exome

AF:

0.0000300

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.0000116

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.000145

Gnomad4 OTH exome

AF:

0.0000498

GnomAD4 genome

AF:

0.0000394

AC:

AN:

152192

Hom.:

Cov.:

AF XY:

0.0000538

AC XY:

AN XY:

74342

show subpopulations

Gnomad4 AFR

AF:

0.0000241

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.000207

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000588

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.000115

Hom.:

Bravo

AF:

0.0000302

ExAC

AF:

0.00000824

AC:

EpiCase

AF:

0.000164

EpiControl

AF:

0.000119

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:8

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Cystic fibrosis

Uncertain:3

Sep 05, 2021

Genome-Nilou Lab

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Aug 12, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces isoleucine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 119 of the CFTR protein (p.Ile119Val). This variant is present in population databases (rs193922518, gnomAD 0.006%). This variant has not been reported in the literature in individuals affected with CFTR-related conditions. ClinVar contains an entry for this variant (Variation ID: 35870). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated. 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. -

Sep 20, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.I119V variant (also known as c.355A>G), located in coding exon 4 of the CFTR gene, results from an A to G substitution at nucleotide position 355. The isoleucine at codon 119 is replaced by valine, an amino acid with highly similar properties. This variant was identified in one asymptomatic carrier with p.F508del in trans (Claustres M et al. Hum. Mutat., 2017 10;38:1297-1315). This amino acid position is not well conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on available evidence to date, the clinical significance of this alteration remains unclear. -

CFTR-related disorder

Uncertain:2

Jun 06, 2018

Natera, Inc.

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Apr 28, 2017

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases did not allow this variant to be ruled in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -

not provided

Uncertain:2

Jun 08, 2017

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The I119V variant in the CFTR gene has not been reported previously in the medical literature as a pathogenic variant, nor as a benign variant, to our knowledge. However, the I119V variant is reported as likely pathogenic in ClinVar by a different clinical laboratory, but additional evidence is not available (ClinVar SCV000052177.1; Landrum et al., 2016). The I119V variant is not observed at a significant frequency in large population cohorts (Lek et al., 2016; 1000 Genomes Consortium et al., 2015; Exome Variant Server). The I119V variant is a conservative amino acid substitution, which is not likely to impact secondary protein structure as these residues share similar properties. This substitution occurs at a position that is conserved in mammals, however, in silico analysis is inconsistent in its predictions as to whether or not the variant is damaging to the protein structure/function. Missense variants in nearby residues (N113I, E116K, E116Q, R117G, R117C, R117L, R117P, A120T, Y122H, Y122C) have been reported in the Human Gene Mutation Database in association with CFTR-related disorders (Stenson et al., 2014), supporting the functional importance of this region of the protein. We interpret I119V as a variant of uncertain significance. -

Sep 27, 2023

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The CFTR c.355A>G; p.Ile119Val variant (rs193922518), is reported in a large COPD cohort but without clear disease association (Saferali 2022). This variant has also been reported in the Cystic Fibrosis Mutation Database in an individual with probable CF, but a second variant was not identified (see link). This variant is reported in ClinVar (Variation ID: 35870), and is found in the general population with an overall allele frequency of 0.003% (8/282,340 alleles) in the Genome Aggregation Database. Computational analyses are uncertain whether this variant is neutral or deleterious (REVEL: 0.611). Due to limited information, the clinical significance of this variant is uncertain at this time. REFERENCES Cystic Fibrosis Mutation Database: http://www.genet.sickkids.on.ca/cftr/MutationDetailPage.external?sp=1231 Saferali A et al. CFTR variants are associated with chronic bronchitis in smokers. Eur Respir J. 2022 Aug 10;60(2):2101994. PMID: 34996830. -

not specified

Uncertain:1

Dec 23, 2024

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: CFTR c.355A>G (p.Ile119Val) results in a conservative amino acid change located in the ABC transporter type 1, transmembrane domain of the encoded protein sequence. Three of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 2.8e-05 in 250942 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. To our knowledge, no occurrence of c.355A>G in individuals affected with Cystic Fibrosis and no experimental evidence demonstrating its impact on protein function have been reported in the literature. CFTR-France database reports one asymptomatic patient that is compound heterozygote for the variant and p.F508del, a CF-causing variant (listed in Claustres_2017). The Sick Kids Cystic Fibrosis Mutation Database reports that the variant was found in a (probable) CF patient whose other variant is as yet unidentified; patient is reported with recurrent chest infections but normal sweat tests. More recently, this variant has been reported as being observed in one allele within the COPDGene study, an observational study of current and former smokers (example, Saferali_2022). These reports do not provide unequivocal conclusions about association of the variant with Cystic Fibrosis/CFTR-related disorders. The following publications have been ascertained in the context of this evaluation (PMID: 28603918, 34996830). ClinVar contains an entry for this variant (Variation ID: 35870). Based on the evidence outlined above, the variant was classified as uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.098

BayesDel_addAF

Pathogenic

0.16

BayesDel_noAF

Pathogenic

0.18

CADD

Benign

DANN

Uncertain

1.0

DEOGEN2

Uncertain

0.45

T;.;.;T;.

Eigen

Uncertain

0.26

Eigen_PC

Uncertain

0.31

FATHMM_MKL

Uncertain

0.93

LIST_S2

Uncertain

0.90

D;D;D;D;D

M_CAP

Uncertain

0.14

MetaRNN

Uncertain

0.62

D;D;D;D;D

MetaSVM

Uncertain

0.18

MutationAssessor

Benign

0.84

L;.;.;.;L

PrimateAI

Benign

0.48

PROVEAN

Benign

0.080

N;.;.;N;.

REVEL

Uncertain

0.61

Sift

Benign

0.29

T;.;.;T;.

Sift4G

Benign

0.34

T;.;.;T;.

Polyphen

0.89

P;.;.;.;.

Vest4

0.87

MVP

0.98

MPC

0.0047

ClinPred

0.39

GERP RS

5.7

Varity_R

0.32

gMVP

0.88

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.0

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over