7-117664685-C-G

Variant names:

• chr7-117664685-C-G
• rs397508652
• NM_000492.4:c.3964-3C>G

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM2 PP3 PP5

The NM_000492.4(CFTR):​c.3964-3C>G variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 33)
• Consequence: CFTR NM_000492.4 splice_region, intron
• Scores: Splicing: ADA: 0.9997
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:3 U:1 O:1
• Conservation: PhyloP100: 0.669
• Publications: 3 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)

ACMG classification

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 7-117664685-C-G is Pathogenic according to our data. Variant chr7-117664685-C-G is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 53864.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CFTR	NM_000492.4	c.3964-3C>G		splice_region_variant, intron_variant	Intron 24 of 26	ENST00000003084.11	NP_000483.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CFTR	ENST00000003084.11	c.3964-3C>G		splice_region_variant, intron_variant	Intron 24 of 26	1	NM_000492.4	ENSP00000003084.6

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Significance: Conflicting classifications of pathogenicity

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

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Cystic fibrosis Pathogenic:2 Uncertain:1 Other:1

Feb 23, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change falls in intron 24 of the CFTR gene. It does not directly change the encoded amino acid sequence of the CFTR protein. It affects a nucleotide within the consensus splice site. This variant is not present in population databases (gnomAD no frequency). This variant has been observed in individual(s) with cystic fibrosis (PMID: 18373402, 26437683, 28603918). This variant is also known as 4096-3C>G. ClinVar contains an entry for this variant (Variation ID: 53864). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Studies have shown that this variant alters mRNA splicing and is expected to lead to the loss of protein expression (PMID: 23381846). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Jan 29, 2018

CFTR-France

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: curation

- -

-

ClinVar Staff, National Center for Biotechnology Information (NCBI)

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

- -

Apr 30, 2024

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.3964-3C>G alters a conserved 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: Two predict the variant abolishes the canonical 3' acceptor site. Two predict the variant weakens the canonical 3' acceptor site. At least one publication reports experimental evidence that this variant affects mRNA splicing by skipping exon 24 (Raynal_2013). The variant was absent in 251058 control chromosomes. c.3964-3C>G has been reported in the literature in at-least two individuals affected with Cystic Fibrosis (example, Raynal_2013, Lakeman_2008). These data indicate that the variant is very likely to be associated with disease. The following publications have been ascertained in the context of this evaluation (PMID: 18373402, 23381846). ClinVar contains an entry for this variant (Variation ID: 53864). Based on the evidence outlined above, the variant was classified as pathogenic. -

Bronchiectasis with or without elevated sweat chloride 1 Pathogenic:1

Apr 08, 2023

Baylor Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.47
CADD	Benign	17
DANN	Benign	0.67
PhyloP100		0.67
Mutation Taster		=10/90	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.96
SpliceAI score (max)		0.94		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.94		Position offset: 3

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

Other links and lift over

dbSNP: rs397508652; hg19: chr7-117304739;