NM_000492.4:c.3468+2dupT

Variant names:

• chr7-117614714-G-GT
• rs1554392800
• NM_000492.4:c.3468+2dupT

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PM2 PP3_Moderate PP5_Very_Strong

The NM_000492.4(CFTR):​c.3468+2dupT variant causes a splice region, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000276 in 1,449,326 control chromosomes in the GnomAD database, with no homozygous occurrence. 1/1 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000028 (0 hom.)
• Consequence: CFTR NM_000492.4 splice_region, intron
• Clinical Significance: Pathogenic reviewed by expert panel P:7
• Conservation: PhyloP100: 7.86
• Publications: 1 publications found

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 Gene-Disease associations (from GenCC):

• cystic fibrosis

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Laboratory for Molecular Medicine, Labcorp Genetics (formerly Invitae), Myriad Women’s Health, Orphanet
• congenital bilateral absence of vas deferens

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• hereditary chronic pancreatitis

  Inheritance: AD Classification: LIMITED Submitted by: Labcorp Genetics (formerly Invitae)

ENSG00000083622 (HGNC:40145):

ACMG classification

Our verdict: Pathogenic. The variant received 12 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 7-117614714-G-GT is Pathogenic according to our data. Variant chr7-117614714-G-GT is described in ClinVar as Pathogenic. ClinVar VariationId is 487380.Status of the report is reviewed_by_expert_panel, 3 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000492.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CFTR	NM_000492.4	MANE Select	c.3468+2dupT		splice_region intron	N/A	NP_000483.3
	CFTR-AS2	NR_199597.1		n.177+1514dupA		intron	N/A

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CFTR	ENST00000003084.11	TSL:1 MANE Select	c.3468+1_3468+2insT		splice_donor intron	N/A	ENSP00000003084.6
	CFTR	ENST00000699602.1		c.3462+1_3462+2insT		splice_donor intron	N/A	ENSP00000514471.1
	CFTR	ENST00000426809.5	TSL:5	c.3378+1_3378+2insT		splice_donor intron	N/A	ENSP00000389119.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000276 AC: 4 AN: 1449326 Hom.: 0 Cov.: 27 AF XY: 0.00000416 AC XY: 3 AN XY: 721804

African (AFR) AF: 0.00 AC: 0 AN: 33144

American (AMR) AF: 0.00 AC: 0 AN: 44648

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25996

East Asian (EAS) AF: 0.00 AC: 0 AN: 39524

South Asian (SAS) AF: 0.00 AC: 0 AN: 86010

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53332

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5742

European-Non Finnish (NFE) AF: 0.00000363 AC: 4 AN: 1101024

Other (OTH) AF: 0.00 AC: 0 AN: 59906

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:7

Revision: reviewed by expert panel

Submissions by phenotype

Cystic fibrosis Pathogenic:5

Nov 05, 2018

Mendelics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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 7 unrelated patients 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, PS3_SUP, PM2_SUP, PM3_VSTR, PP4

Sep 16, 2020

Natera, Inc.

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

Jan 27, 2022

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.3468+2dupT (also called as 3600+2insT or c.3468+2_3468+3insT, according to an older nomenclature) alters a nucleotide located close to a canonical splice site and therefore could affect mRNA splicing, leading to a significantly altered protein sequence. Several computational tools predict a significant impact on normal splicing: four predict the variant abolishes a 5' splicing donor site. At least one publication reported experimental evidence confirming in a mini-gene assay that this variant affects mRNA splicing, and demonstrated no detectable protein in transfected HEK293 cells (Joynt_2020). The variant was absent in 250770 control chromosomes (gnomAD). c.3468+2dupT has been reported in the literature in multiple individuals affected with Cystic Fibrosis (e.g. Van Biervliet 2007, Krenkova 2012, Zietkiewicz 2014, Medza_2021). These data indicate that the variant is very likely to be associated with disease. Four clinical diagnostic laboratories (including an expert panel, CFTR2) have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation, and all laboratories classified the variant as pathogenic/likely pathogenic, and the expert panel has classified the variant pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic.

Mar 17, 2017

CFTR2

Significance: Pathogenic

Review Status: reviewed by expert panel

Collection Method: research

not provided Pathogenic:1

Dec 27, 2016

Eurofins Ntd Llc (ga)

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Bronchiectasis with or without elevated sweat chloride 1 Pathogenic:1

Jan 13, 2024

Baylor Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		7.9
Mutation Taster		=1/99	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.98		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.98		Position offset: -1

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

Other links and lift over

dbSNP: rs1554392800; hg19: chr7-117254768;