7-117652877-C-G

Variant names:

• chr7-117652877-C-G
• rs80034486
• NM_000492.4:c.3909C>G

Variant summary

Our verdict is Pathogenic. Variant got 15 ACMG points: 15P and 0B. PM1 PM2 PM5 PP3 PP5_Very_Strong

The NM_000492.4(CFTR):​c.3909C>G​(p.Asn1303Lys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000158 in 1,598,060 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 (★★★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. N1303I) has been classified as Pathogenic.

• Frequency:
  • Genomes: 𝑓 0.00016 (0 hom., cov: 32)
  • Exomes 𝑓: 0.00016 (0 hom.)
• Consequence: CFTR NM_000492.4 missense
• Clinical Significance: Pathogenic practice guideline P:41 U:1 O:2
• Conservation: PhyloP100: 0.670

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 Pathogenic. Variant got 15 ACMG points.

• PM1: In a helix (size 4) in uniprot entity CFTR_HUMAN there are 4 pathogenic changes around while only 0 benign (100%) in NM_000492.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr7-117652876-A-T is described in Lovd as [Pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.778
• PP5: Variant 7-117652877-C-G is Pathogenic according to our data. Variant chr7-117652877-C-G is described in ClinVar as [Pathogenic]. Clinvar id is 7136.Status of the report is practice_guideline, 4 stars. Variant chr7-117652877-C-G is described in Lovd as [Pathogenic]. Variant chr7-117652877-C-G is described in Lovd as [Pathogenic]. Variant chr7-117652877-C-G is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CFTR	NM_000492.4	c.3909C>G	p.Asn1303Lys	missense_variant	Exon 24 of 27	ENST00000003084.11	NP_000483.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CFTR	ENST00000003084.11	c.3909C>G	p.Asn1303Lys	missense_variant	Exon 24 of 27	1	NM_000492.4	ENSP00000003084.6

Frequencies

GnomAD3 genomes AF: 0.000158 AC: 24 AN: 152068 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000656

Gnomad ASJ AF: 0.000865

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000235

Gnomad OTH AF: 0.000955

GnomAD3 exomes AF: 0.000144 AC: 36 AN: 249546 Hom.: 0 AF XY: 0.000171 AC XY: 23 AN XY: 134794

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000146

Gnomad ASJ exome AF: 0.000599

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000330

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000186

Gnomad OTH exome AF: 0.000493

GnomAD4 exome AF: 0.000158 AC: 228 AN: 1445874 Hom.: 0 Cov.: 27 AF XY: 0.000179 AC XY: 129 AN XY: 720082

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.000112

Gnomad4 ASJ exome AF: 0.000500

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000586

Gnomad4 FIN exome AF: 0.0000187

Gnomad4 NFE exome AF: 0.000172

Gnomad4 OTH exome AF: 0.000201

GnomAD4 genome AF: 0.000158 AC: 24 AN: 152186 Hom.: 0 Cov.: 32 AF XY: 0.000148 AC XY: 11 AN XY: 74420

Gnomad4 AFR AF: 0.0000241

Gnomad4 AMR AF: 0.0000655

Gnomad4 ASJ AF: 0.000865

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.000207

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000235

Gnomad4 OTH AF: 0.000945

Alfa AF: 0.000263 Hom.: 0

Bravo AF: 0.000204

TwinsUK AF: 0.000539 AC: 2

ALSPAC AF: 0.00 AC: 0

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000349 AC: 3

ExAC AF: 0.000148 AC: 18

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:41 Uncertain:1 Other:2

Revision: practice guideline

Submissions by phenotype

Cystic fibrosis Pathogenic:19 Uncertain:1 Other:2

Mar 17, 2017

CFTR2

Significance: Pathogenic

Review Status: reviewed by expert panel

Collection Method: research

- -

Aug 01, 1992

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

-

GeneReviews

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

- -

Sep 01, 2017

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This mutation has been previously reported as disease-causing and was found once in our laboratory in a homozygous state in a 13-year-old male with a clinical diagnosis of cystic fibrosis. Heterozygotes are expected to be asymptomatic carriers. -

Apr 27, 2022

MGZ Medical Genetics Center

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Aug 29, 2014

Courtagen Diagnostics Laboratory, Courtagen Life Sciences

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Sep 25, 2019

Genome Diagnostics Laboratory, The Hospital for Sick Children

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Mar 26, 2025

Institute of Human Genetics, University of Leipzig Medical Center

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Criteria applied: PM3_VSTR,PS3,PM5,PM2_SUP,PP3,PP4 -

Jan 29, 2018

CFTR-France

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: curation

- -

Jan 22, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces asparagine, which is neutral and polar, with lysine, which is basic and polar, at codon 1303 of the CFTR protein (p.Asn1303Lys). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This missense change has been observed in individuals with CFTR-related disorders, including cystic fibrosis, congenital bilateral absence of the vas deferens, and chronic pancreatitis (PMID: 1380943, 12767731, 15371902, 21520337, 22658665, 23951356, 23974870). ClinVar contains an entry for this variant (Variation ID: 7136). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) 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, 25799511). For these reasons, this variant has been classified as Pathogenic. -

Oct 04, 2024

Al Jalila Children’s Genomics Center, Al Jalila Childrens Speciality Hospital

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: research

PS3,PM3(strong),PP3,PM2,PM5 -

-

Genomics And Bioinformatics Analysis Resource, Columbia University

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: research

- -

Nov 05, 2018

Mendelics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Feb 03, 2016

Counsyl

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Sep 05, 2017

Illumina Laboratory Services, Illumina

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The CFTR c.3909C>G (p.Asn1303Lys) missense variant is a well-known, widely reported pathogenic variant that accounts for approximately 1.3% of disease alleles, and is often associated with a classic cystic fibrosis (CF) phenotype (Ong et al. 2001). The Cystic Fibrosis Mutation Database (http://www.genet.sickkids.on.ca/cftr/Home.html) indicates that the p.Asn1303Lys variant is the fourth most common CFTR variant worldwide, and the Clinical and Functional Translation of CFTR (CFTR2) database (http://cftr2.org) reports the p.Asn1303Lys variant in over 2100 patients, noting that it is a cystic fibrosis-causing variant. Across a selection of the available literature, the p.Asn1303Lys variant has also been reported in five patients with congenital bilateral absence of the vas deferens (CBAVD), including three compound heterozygotes and two heterozygotes in whom a second variant was not identified (Steiner et al. 2011; Tomaiuolo et al. 2011), and in four patients with chronic pancreatitis, including three compound heterozygotes and one heterozygote (Steiner et al. 2011; Hamoir et al. 2013). The p.Asn1303Lys variant is reported at a frequency of 0.00035 in the European American population of the Exome Sequencing Project. Based on the collective evidence, the p.Asn1303Lys variant is classified as pathogenic for CFTR-related disorders. This variant was observed by ICSL as part of a predisposition screen in an ostensibly healthy population. -

Apr 04, 2024

Genomic Medicine Center of Excellence, King Faisal Specialist Hospital and Research Centre

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Feb 18, 2022

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.N1303K pathogenic mutation (also known as c.3909C>G), located in coding exon 24 of the CFTR gene, results from a C to G substitution at nucleotide position 3909. The asparagine at codon 1303 is replaced by lysine, an amino acid with similar properties. In one study, this mutation was identified in 216 cystic fibrosis alleles, including 10 homozygous individuals with elevated sweat chloride levels and decreased lung function. Of the 6 homozygous individuals with reported pancreatic status, all were pancreatic insufficient (Osborne L et al. Hum. Genet., 1992 Aug;89:653-8). In vitro functional studies determined that this mutation prevents the maturation, trafficking, and subsequent activity of the CFTR protein (Gregory RJ et al. Mol. Cell. Biol., 1991 Aug;11:3886-93). This pathogenic mutation is associated with elevated sweat chloride levels, decreased lung function, and pancreatic insufficiency; in vitro functional studies showed this mutation results in significantly reduced chloride conductance (Sosnay PR et al. Nat. Genet., 2013 Oct;45:1160-7). Based on the supporting evidence, this alteration is interpreted as a disease-causing mutation. -

Nov 21, 2018

Equipe Genetique des Anomalies du Developpement, Université de Bourgogne

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Oct 10, 2018

Undiagnosed Diseases Network, NIH

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

-

GenomeConnect, ClinGen

Significance: not provided

Review Status: no classification provided

Collection Method: phenotyping only

Variant interpretted as pathogenic and reported on 03/20/2016 by GTR ID 500068. GenomeConnect assertions are reported exactly as they appear on the patient-provided report from the testing laboratory. GenomeConnect staff make no attempt to reinterpret the clinical significance of the variant. -

Mar 03, 2004

American College of Medical Genetics and Genomics (ACMG)

Significance: Pathogenic

Review Status: practice guideline

Collection Method: curation

- -

Sep 23, 2022

Human Genetics Bochum, Ruhr University Bochum

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

ACMG criteria used to clasify this variant: PS3, PS4, PP3, PP1 -

not provided Pathogenic:14

-

Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Aug 19, 2024

Mayo Clinic Laboratories, Mayo Clinic

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

May 27, 2022

Clinical Genetics Laboratory, Skane University Hospital Lund

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Aug 22, 2022

Revvity Omics, Revvity

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

-

Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Feb 22, 2023

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The frequency of this variant in the general population, 0.00018 (23/128054 chromosomes, http://gnomad.broadinstitute.org), is uninformative in assessment of its pathogenicity. In the published literature, the variant has been reported in the homozygous state and with other CF variants in trans to be particularly associated with a pancreatic insufficient phenotype, however, variable lung function phenotypes from unusually mild to severe have been observed (PMID: 1380943 (1992), 23974870 (2013), and 26208274 (2015)). Functional analysis has described this variant as Class II causing defective protein processing, protein degradation, insignificant levels of mature CFTR, and conductance (PMID: 1712898 (1991), 23891399 (2014), 25799511 (2015), 26823392 (2016)). Analysis of this variant using bioinformatics tools for the prediction of the effect of amino acid changes on protein structure and function yielded predictions that this variant is damaging. Based on the available information, this variant is classified as pathogenic. -

May 10, 2019

Clinical Genetics and Genomics, Karolinska University Hospital

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Feb 11, 2015

Center for Pediatric Genomic Medicine, Children's Mercy Hospital and Clinics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Nov 03, 2022

Institute for Clinical Genetics, University Hospital TU Dresden, University Hospital TU Dresden

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Oct 26, 2023

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The CFTR c.3909C>G; p.Asn1303Lys variant (rs80034486), is reported in the literature in multiple individuals diagnosed with cystic fibrosis, often associated with pancreatic insufficiency (Osborne 1991, Osborne 1992, Ooi 2012, Sosnay 2013, CFTR2 database). This variant is reported in ClinVar (Variation ID: 7136), and is found in the general population with an overall allele frequency of 0.014% (34/244424 alleles) in the Genome Aggregation Database. The asparagine at codon 1303 is highly conserved, and computational analyses predict that this variant is deleterious (REVEL: 0.83). Functional characterization of the variant protein indicates a defect in CFTR processing, resulting in a severe reduction in chloride transport activity (Sosnay 2013, Van Goor 2014). Based on available information, this variant is considered to be pathogenic. References: CFTR2 database: http://cftr2.org Ooi C. et al. Cystic fibrosis transmembrane conductance regulator (CFTR) gene mutations in pancreatitis. J Cyst Fibros. 2012 11(5):355-62. PMID: 22658665 Osborne L et al. A mutation in the second nucleotide binding fold of the cystic fibrosis gene. Am J Hum Genet. 1991 48(3):608-12. PMID: 1998343 Osborne L et al. Incidence and expression of the N1303K mutation of the cystic fibrosis (CFTR) gene. Hum Genet. 1992 89(6):653-8. PMID: 1380943 Sosnay PR et al. Defining the disease liability of variants in the cystic fibrosis transmembrane conductance regulator gene. Nat Genet. 2013 45(10):1160-7. PMID: 23974870 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 13(1):29-36. PMID: 23891399 -

May 15, 2018

Eurofins Ntd Llc (ga)

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Oct 01, 2019

CeGaT Center for Human Genetics Tuebingen

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

-

Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Dec 31, 2018

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The N1303K variant in the CFTR gene has been reported previously as a CF-causing variant in patients with abnormal sweat chloride levels, pancreatic insufficiency, and mild to moderate lung disease (Sosnay et al., 2013; Osborne et al, 1991). The N1303K variant was not observed at any significant frequency in approximately 6500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. The N1303K variant is a semi-conservative amino acid substitution, which may impact secondary protein structure as these residues differ in some properties. This substitution occurs at a position within the ABC transporter 2 domain that is conserved across species. Cell lines expressing the N1303K CFTR variant show loss of baseline chloride transport compared to those expressing wild type protein (Van Goor et al., 2014). A missense variant at the same residue, N1303H, was reported in a patient with severe pulmonary disease and pancreatic insufficiency (Claustres et al., 1992). We interpret N1303K as a pathogenic variant. -

CFTR-related disorder Pathogenic:3

Sep 25, 2019

Genome Diagnostics Laboratory, The Hospital for Sick Children

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Mar 17, 2017

Natera, Inc.

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Jun 21, 2024

PreventionGenetics, part of Exact Sciences

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

The CFTR c.3909C>G variant is predicted to result in the amino acid substitution p.Asn1303Lys. This variant has been reported to be causative for cystic fibrosis (Sosnay et al. 2013. PubMed ID: 23974870; Masson et al. 2013. PubMed ID: 23951356; Osborne et al. 1991. PubMed ID: 1998343; Watson et al. 2004. PubMed ID: 15371902). This variant is reported in 0.058% of alleles in individuals of Ashkenazi Jewish descent in gnomAD. This variant is interpreted as pathogenic. -

Spermatogenic failure, Y-linked, 2 Pathogenic:1

Jun 07, 2018

Institute of Human Genetics, University Hospital Muenster

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

ACMG categories: PS3,PS4,PP3,PP5 -

Cystic fibrosis;C0403814:Congenital bilateral aplasia of vas deferens from CFTR mutation Pathogenic:1

-

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Hereditary pancreatitis Pathogenic:1

May 25, 2021

Sema4, Sema4

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: curation

- -

Cystic fibrosis;C0238339:Hereditary pancreatitis;C0403814:Congenital bilateral aplasia of vas deferens from CFTR mutation;C2749757:Bronchiectasis with or without elevated sweat chloride 1 Pathogenic:1

May 06, 2024

Fulgent Genetics, Fulgent Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Bronchiectasis with or without elevated sweat chloride 1 Pathogenic:1

Mar 29, 2024

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Uncertain	0.079	D
BayesDel_noAF	Pathogenic	0.14
CADD	Benign	22
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.97	D;D;.
Eigen	Uncertain	0.48
Eigen_PC	Uncertain	0.29
FATHMM_MKL	Benign	0.53	D
LIST_S2	Uncertain	0.96	D;D;D
M_CAP	Pathogenic	0.30	D
MetaRNN	Pathogenic	0.78	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.9	H;.;.
PrimateAI	Uncertain	0.71	T
PROVEAN	Pathogenic	-5.1	D;D;.
REVEL	Pathogenic	0.83
Sift	Pathogenic	0.0	D;D;.
Sift4G	Uncertain	0.0040	D;D;.
Polyphen		1.0	D;.;.
Vest4		0.97
MutPred		0.96		Gain of ubiquitination at N1303 (P = 0.03);.;.;
MVP		0.99
MPC		0.016
ClinPred		0.86	D
GERP RS		1.3
Varity_R		0.99
gMVP		0.97

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

Other links and lift over

dbSNP: rs80034486; hg19: chr7-117292931;