NM_000492.4:c.1883G>C

Variant names:

• chr7-117592050-G-C
• rs1554389290
• NM_000492.4:c.1883G>C

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5

The NM_000492.4(CFTR):​c.1883G>C​(p.Gly628Ala) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G628R) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: CFTR NM_000492.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:2
• Conservation: PhyloP100: 9.23
• 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)

ACMG classification

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

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 15 uncertain 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 chr7-117592049-G-C is described in ClinVar as Pathogenic. ClinVar VariationId is 53409.Status of the report is reviewed_by_expert_panel, 3 stars.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 197 curated pathogenic missense variants (we use a threshold of 10). The gene has 46 curated benign missense variants. Gene score misZ: -3.1397 (below the threshold of 3.09). Trascript score misZ: -1.0868 (below the threshold of 3.09). GenCC associations: The gene is linked to hereditary chronic pancreatitis, cystic fibrosis, congenital bilateral absence of vas deferens.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.979
• PP5: Variant 7-117592050-G-C is Pathogenic according to our data. Variant chr7-117592050-G-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 555466.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CFTR	NM_000492.4	c.1883G>C	p.Gly628Ala	missense_variant	Exon 14 of 27	ENST00000003084.11	NP_000483.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CFTR	ENST00000003084.11	c.1883G>C	p.Gly628Ala	missense_variant	Exon 14 of 27	1	NM_000492.4	ENSP00000003084.6

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Cystic fibrosis Pathogenic:2 Uncertain:2

Jul 03, 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.1883G>C (p.Gly628Ala) results in a non-conservative amino acid change located in the ABC transporter-like, ATP-binding domain (IPR003439) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 245128 control chromosomes. c.1883G>C has been reported in the literature in individuals affected with Cystic Fibrosis (Kharrazi_2015). A different variant affecting the same codon has been classified as pathogenic by our lab (c.1882G>C, p.Gly628Arg), supporting the critical relevance of codon 628 to CFTR protein function. At least one publication reports experimental evidence evaluating an impact on protein function. The most pronounced variant effect resulted in approximately 3% of normal chloride channel conductance relative to wild type (e.g., Bihler_2024). The following publications have been ascertained in the context of this evaluation (PMID: 26574590, 28471435, 38388235). ClinVar contains an entry for this variant (Variation ID: 555466). Based on the evidence outlined above, the variant was classified as pathogenic. -

Sep 27, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. This variant disrupts the p.Gly628 amino acid residue in CFTR. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 10923036, 20435887, 27022295). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt CFTR protein function. ClinVar contains an entry for this variant (Variation ID: 555466). This missense change has been observed in individual(s) with cystic fibrosis (PMID: 26574590). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glycine, which is neutral and non-polar, with alanine, which is neutral and non-polar, at codon 628 of the CFTR protein (p.Gly628Ala). -

Dec 27, 2022

Johns Hopkins Genomics, Johns Hopkins University

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This CFTR variant has been reported in individuals with features of cystic fibrosis and has an entry in ClinVar (Variation ID: 555466)3. It is absent from a large population dataset. Two bioinformatic tools queried predict that this substitution would be damaging and the glycine residue at this position is evolutionarily conserved across all species assessed. A different missense variant (p.Gly628Arg) at this same position has been classified as a CF-causing variant. We consider CFTR c.1883G>C to be likely pathogenic. -

Dec 07, 2017

Counsyl

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.66
BayesDel_addAF	Pathogenic	0.53	D
BayesDel_noAF	Pathogenic	0.52
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.88	D;.;T;.
Eigen	Pathogenic	0.93
Eigen_PC	Pathogenic	0.91
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D;D;D;D
M_CAP	Pathogenic	0.67	D
MetaRNN	Pathogenic	0.98	D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Uncertain	2.4	M;.;.;.
PhyloP100		9.2
PrimateAI	Pathogenic	0.81	D
PROVEAN	Pathogenic	-5.3	D;.;D;.
REVEL	Pathogenic	0.96
Sift	Uncertain	0.0030	D;.;D;.
Sift4G	Uncertain	0.0030	D;.;D;.
Polyphen		1.0	D;.;.;.
Vest4		0.94
MutPred		0.87		Gain of catalytic residue at G628 (P = 0.0315);.;.;.;
MVP		1.0
MPC		0.016
ClinPred		0.99	D
GERP RS		5.6
Varity_R		0.92
gMVP		0.95
Mutation Taster		=11/89	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.070		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs1554389290; hg19: chr7-117232104;