chr7-117603748-AG-A

Variant names:

• chr7-117603748-AG-A
• rs397508447
• NM_000492.4:c.2875delG

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000492.4(CFTR):​c.2875delG​(p.Ala959HisfsTer9) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000616 in 1,461,716 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000062 (0 hom.)
• Consequence: CFTR NM_000492.4 frameshift
• Clinical Significance: Pathogenic reviewed by expert panel P:11
• Conservation: PhyloP100: 9.76

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 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 7-117603748-AG-A is Pathogenic according to our data. Variant chr7-117603748-AG-A is described in ClinVar as [Pathogenic]. Clinvar id is 53583.Status of the report is reviewed_by_expert_panel, 3 stars. Variant chr7-117603748-AG-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CFTR	NM_000492.4	c.2875delG	p.Ala959HisfsTer9	frameshift_variant	Exon 17 of 27	ENST00000003084.11	NP_000483.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CFTR	ENST00000003084.11	c.2875delG	p.Ala959HisfsTer9	frameshift_variant	Exon 17 of 27	1	NM_000492.4	ENSP00000003084.6

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251356 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135830

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: 0.00000880

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000616 AC: 9 AN: 1461716 Hom.: 0 Cov.: 32 AF XY: 0.00000550 AC XY: 4 AN XY: 727148

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: 0.00000719

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:11

Revision: reviewed by expert panel

Submissions by phenotype

Cystic fibrosis Pathogenic:8

Nov 12, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Ala959Hisfs*9) in the CFTR gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in CFTR are known to be pathogenic (PMID: 1695717, 7691345, 9725922). This variant is present in population databases (rs397508447, gnomAD 0.0009%). This premature translational stop signal has been observed in individual(s) with cystic fibrosis (PMID: 23974870). ClinVar contains an entry for this variant (Variation ID: 53583). For these reasons, this variant has been classified as Pathogenic. -

Apr 11, 2024

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.2875delG pathogenic mutation, located in coding exon 17 of the CFTR gene, results from a deletion of one nucleotide at nucleotide position 2875, causing a translational frameshift with a predicted alternate stop codon (p.A959Hfs*9). This alteration is associated with elevated sweat chloride levels, decreased lung function, pancreatic insufficiency, and Pseudomonas infection (Sosnay PR, Nat. Genet. 2013 Oct; 45(10):1160-7). In addition to the clinical data presented in the literature, this alteration is expected to result in loss of function by premature protein truncation or nonsense-mediated mRNA decay. As such, this alteration is interpreted as a disease-causing mutation. -

Jan 29, 2018

CFTR-France

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: curation

- -

Mar 17, 2017

CFTR2

Significance: Pathogenic

Review Status: reviewed by expert panel

Collection Method: research

- -

Sep 05, 2022

Institute of Human Genetics, University of Leipzig Medical Center

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: curation

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: PVS1, PM2_SUP, PM3_VSTR -

Nov 02, 2018

Illumina Laboratory Services, Illumina

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The CFTR c.2875delG (p.Ala959HisfsTer9) variant, also referred to in the literature as c.3007delG, results in a frameshift and a premature truncation of the protein. This variant is widely reported in the literature and is classified as a cystic fibrosis (CF)-causing mutation according to the CFTR2 mutation database (www.cftr2.org). The database states the mutation has been observed in 40 CF individuals. Across a selection of the available literature, the p.Ala959HisfsTer9 variant was found in three compound heterozygous CF probands, in seven heterozygous probands with CF or congenital bilateral absence of vas deferens (CBAVD) and in 31 additional proband alleles (Mercier et al. 1994; Claustres et al. 2000; Scotet et al. 2003; des Georges et al. 2004; Dorfman et al. 2010; Sosnay et al. 2013). Control data are unavailable for this variant, which is reported at a frequency of 0.00012 in the European American population of the Exome Sequencing Project but this is based on one allele in a region of good sequencing coverage, so the variant is presumed to be rare. Based on the collective evidence and the potential impact of frameshift variants, the p.Ala959HisfsTer9 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 22, 2020

Johns Hopkins Genomics, Johns Hopkins University

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Disease-causing CFTR variant. See www.CFTR2.org for phenotype information. -

Oct 14, 2014

Counsyl

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: literature only

- -

not specified Pathogenic:1

Jul 31, 2018

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

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: CFTR c.2875delG (p.Ala959HisfsX9) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Truncations downstream of this position have been classified as pathogenic by our laboratory (e.g., p.Trp1089X, p.Tyr1092X). The variant allele was found at a frequency of 4.1e-06 in 246118 control chromosomes. c.2875delG has been reported in the literature in multiple individuals affected with Cystic Fibrosis. These data indicate that the variant is very likely to be associated with disease. One clinical diagnostic laboratory has submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation and classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

CFTR-related disorder Pathogenic:1

Mar 17, 2017

Natera, Inc.

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

not provided Pathogenic:1

Apr 13, 2019

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The variant results in a shift of the reading frame, and is therefore predicted to result in the loss of a functional protein. Found in at least one symptomatic patient, and found in general population data that is consistent with pathogenicity. -

Computational scores

Source: dbNSFP v4.3

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: rs397508447; hg19: chr7-117243802;