rs397508744

chr7-117534309-A-G

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM1 PM2 PP3_Moderate PP5

The NM_000492.4(CFTR):c.523A>G(p.Ile175Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000689 in 1,452,122 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 Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. I175I) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: CFTR NM_000492.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:4 U:3 O:1
• Conservation: PhyloP100: 8.47

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]

ACMG classification

Verdict is Likely_pathogenic. Variant got 7 ACMG points.

• PM1: In a domain ABC transmembrane type-1 1 (size 284) in uniprot entity CFTR_HUMAN there are 173 pathogenic changes around while only 18 benign (91%) in NM_000492.4
• 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.
• PP5: Variant 7-117534309-A-G is Pathogenic according to our data. Variant chr7-117534309-A-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 53986.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=3, Likely_pathogenic=2, not_provided=1, Pathogenic=2}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CFTR	NM_000492.4	c.523A>G	p.Ile175Val	missense_variant	5/27	ENST00000003084.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CFTR	ENST00000003084.11	c.523A>G	p.Ile175Val	missense_variant	5/27	1	NM_000492.4	P2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.89e-7 AC: 1 AN: 1452122 Hom.: 0 Cov.: 26 AF XY: 0.00000138 AC XY: 1 AN XY: 723044

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:4 Uncertain:3 Other:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Cystic fibrosis Pathogenic:3 Uncertain:3 Other:1

Uncertain significance, criteria provided, single submitter	curation	Institute of Human Genetics, University of Leipzig Medical Center	Sep 05, 2022	This variant was identified in 1 patient with a clinically confirmed diagnosis of cystic fibrosis. The variant was classified in the context of a project re-classifying variants in the German Cystic Fibrosis Registry (Muko.e.V.). Link: https://www.muko.info/angebote/qualitaetsmanagement/register/cf-einrichtungen/mukoweb. Criteria applied: PM3, PM2_SUP, PP3, PP4 -
Uncertain significance, criteria provided, single submitter	clinical testing	Counsyl	Apr 17, 2017	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Mar 08, 2023	Variant summary: CFTR c.523A>G (p.Ile175Val) results in a conservative amino acid change located in the transmembrane domain (IPR011527) of the encoded protein sequence. Three of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 250706 control chromosomes (gnomAD). c.523A>G has been reported in the literature in the homozygous state in multiple individuals affected with Cystic Fibrosis, including at least one family in which it segregated with the disease phenotype (e.g. Romey_1994, Behar_2017, Alsamri_2020). These data indicate that the variant is very likely to be associated with disease. However, at least two publications report experimental evidence evaluating an impact on protein function and showed no damaging effect of this variant in vitro (e.g. Seibert_1997, Caputo_2009). Five submitters have provided clinical-significance assessments for this variant to ClinVar after 2014 . Multiple laboratories reported the variant with conflicting assessments, classifying the variant as either VUS (n=3) or pathogenic (n=2). Based on the evidence outlined above, the variant was classified as likely pathogenic. -
not provided, no classification provided	literature only	ClinVar Staff, National Center for Biotechnology Information (NCBI)	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Nov 17, 2023	This sequence change replaces isoleucine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 175 of the CFTR protein (p.Ile175Val). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individuals with cystic fibrosis (PMID: 7520799, 28546993). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 53986). 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 are conflicting or provide insufficient evidence to determine the effect of this variant on CFTR function (PMID: 9305991, 19491324). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -
Uncertain significance, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Jul 22, 2021	- -
Pathogenic, criteria provided, single submitter	curation	CFTR-France	Jul 03, 2015	- -

Bronchiectasis with or without elevated sweat chloride 1 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Baylor Genetics

May 29, 2023

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.19
BayesDel_addAF	Pathogenic	0.38	D
BayesDel_noAF	Pathogenic	0.31
Cadd	Pathogenic	34
Dann	Uncertain	1.0
DEOGEN2	Uncertain	0.47	T;.;.;.
Eigen	Pathogenic	0.73
Eigen_PC	Pathogenic	0.74
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D;D;D;D
M_CAP	Pathogenic	0.56	D
MetaRNN	Pathogenic	0.85	D;D;D;D
MetaSVM	Uncertain	0.60	D
MutationAssessor	Uncertain	2.0	M;.;.;M
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.81	D
PROVEAN	Benign	-0.050	N;.;.;.
REVEL	Pathogenic	0.75
Sift	Benign	0.065	T;.;.;.
Sift4G	Pathogenic	0.0	D;.;.;.
Polyphen		0.99	D;.;.;.
Vest4		0.86
MutPred		0.78		Gain of methylation at K174 (P = 0.0764);Gain of methylation at K174 (P = 0.0764);Gain of methylation at K174 (P = 0.0764);Gain of methylation at K174 (P = 0.0764);
MVP		0.99
MPC		0.0074
ClinPred		0.83	D
GERP RS		5.5
Varity_R		0.42
gMVP		0.79

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.99		Position offset: -1

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

Publications

LitVar

Other links and lift over

dbSNP: rs397508744; hg19: chr7-117174363;