NM_000492.4:c.171G>A

Variant names:

• chr7-117509040-G-A
• rs121909025
• NM_000492.4:c.171G>A

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.171G>A​(p.Trp57*) variant causes a stop gained change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000069 in 1,450,132 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 (★★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: CFTR NM_000492.4 stop_gained
• Clinical Significance: Pathogenic reviewed by expert panel P:7
• Conservation: PhyloP100: 7.71

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 7-117509040-G-A is Pathogenic according to our data. Variant chr7-117509040-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 7179.Status of the report is reviewed_by_expert_panel, 3 stars. Variant chr7-117509040-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CFTR	NM_000492.4	c.171G>A	p.Trp57*	stop_gained	Exon 3 of 27	ENST00000003084.11	NP_000483.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CFTR	ENST00000003084.11	c.171G>A	p.Trp57*	stop_gained	Exon 3 of 27	1	NM_000492.4	ENSP00000003084.6

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.90e-7 AC: 1 AN: 1450132 Hom.: 0 Cov.: 28 AF XY: 0.00 AC XY: 0 AN XY: 722336

Gnomad4 AFR exome AF: 0.0000301

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.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:7

Revision: reviewed by expert panel

Submissions by phenotype

Cystic fibrosis Pathogenic:6

Sep 14, 2015

Counsyl

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Mar 17, 2017

CFTR2

Significance: Pathogenic

Review Status: reviewed by expert panel

Collection Method: research

- -

Jan 29, 2018

CFTR-France

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: curation

- -

Oct 27, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 7179). This variant is also known as c.303G>A. This premature translational stop signal has been observed in individual(s) with cystic fibrosis (PMID: 11379874, 16049310, 30444886). This variant is not present in population databases (gnomAD no frequency). This sequence change creates a premature translational stop signal (p.Trp57*) 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). -

Jul 31, 2023

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.171G>A (p.Trp57X) 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. Variants downstream of this position have been classified as pathogenic by our laboratory. The variant was absent in 250782 control chromosomes (gnomAD). c.171G>A has been reported in the literature in individuals affected with Cystic Fibrosis (example: Roth_2011). The following publication has been ascertained in the context of this evaluation (PMID: 21909392). Six submitters have cited clinical-significance assessments for this variant to ClinVar after 2014. All submitters classified the variant as pathogenic/likely pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

Apr 09, 2018

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

CFTR-related disorder Pathogenic:1

Mar 17, 2017

Natera, Inc.

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.65
CADD	Pathogenic	39
DANN	Uncertain	0.99
Eigen	Pathogenic	0.98
Eigen_PC	Pathogenic	0.88
FATHMM_MKL	Pathogenic	0.97	D
Vest4		0.89
GERP RS		5.7

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs121909025; hg19: chr7-117149094; COSMIC: COSV99134689; COSMIC: COSV99134689;