7-117531001-G-A

Variant names:

• chr7-117531001-G-A
• rs397508606
• NM_000492.4:c.376G>A

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM1 PM2 PM5 PP3_Strong PP5

The NM_000492.4(CFTR):​c.376G>A​(p.Gly126Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000479 in 1,460,062 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 Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G126D) has been classified as Pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000048 (0 hom.)
• Consequence: CFTR NM_000492.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:2 O:1
• Conservation: PhyloP100: 9.52

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 11 ACMG points.

• PM1: In a domain ABC transmembrane type-1 1 (size 284) in uniprot entity CFTR_HUMAN there are 65 pathogenic changes around while only 10 benign (87%) 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 chr7-117531002-G-A is described in Lovd as [Pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.982
• PP5: Variant 7-117531001-G-A is Pathogenic according to our data. Variant chr7-117531001-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 53808.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=2, Pathogenic=1, not_provided=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CFTR	NM_000492.4	c.376G>A	p.Gly126Ser	missense_variant	Exon 4 of 27	ENST00000003084.11	NP_000483.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CFTR	ENST00000003084.11	c.376G>A	p.Gly126Ser	missense_variant	Exon 4 of 27	1	NM_000492.4	ENSP00000003084.6

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000797 AC: 2 AN: 250896 Hom.: 0 AF XY: 0.0000148 AC XY: 2 AN XY: 135580

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: 0.0000654

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000479 AC: 7 AN: 1460062 Hom.: 0 Cov.: 31 AF XY: 0.00000826 AC XY: 6 AN XY: 726414

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: 0.0000812

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ExAC AF: 0.0000165 AC: 2

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:2 Other:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Cystic fibrosis Pathogenic:1 Uncertain:1 Other:1

-

ClinVar Staff, National Center for Biotechnology Information (NCBI)

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

- -

Sep 01, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glycine with serine at codon 126 of the CFTR protein (p.Gly126Ser). The glycine residue is moderately conserved and there is a small physicochemical difference between glycine and serine. This variant is present in population databases (rs397508606, ExAC 0.01%). This missense change has been observed in individual(s) with clinical features of cystic fibrosis (PMID: 19181743, 25042876). This variant is also known as c.508G>A. ClinVar contains an entry for this variant (Variation ID: 53808). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). Experimental studies have shown that this missense change does not substantially affect CFTR function (PMID: 25042876). This variant disrupts the p.Gly126 amino acid residue in CFTR. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 8163293, 10439967, 23974870, 27214204). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. 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. -

May 03, 2020

Genomic Research Center, Shahid Beheshti University of Medical Sciences

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Congenital bilateral aplasia of vas deferens from CFTR mutation Pathogenic:1

Jul 22, 2021

Genome-Nilou Lab

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not specified Uncertain:1

Jan 21, 2025

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

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: CFTR c.376G>A (p.Gly126Ser) results in a non-conservative amino acid change located in the ABC transporter type 1, transmembrane domain (IPR011527) of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. Consensus agreement among computation tools predict no significant impact on normal splicing. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 8e-06 in 250896 control chromosomes (gnomAD). c c.376G>A has been reported in the literature in at least one heterozygous individual affected with congenital bilateral absence of vas deferens (CBAVD), repeated respiratory infections and raised sweat chloride levels without a clinical diagnosis of cystic fibrosis (Sharma_2009). This report, however, does not provide unequivocal conclusions about association of the variant with cystic fibrosis. An experimental study measuring channel function by iodide efflux of the mutant protein compared to WT found to have normal protein maturation process and channel activity (Sharma _2015). However, a recent study conducted by Bihler et al reports approximately 25% of normal chloride channel conductance relative to wild type (Bihler_2024). The following publications have been ascertained in the context of this evaluation (PMID: 19181743, 25042876, 38388235, 35913788). ClinVar contains an entry for this variant (Variation ID: 53808). Based on the evidence outlined above, the variant was classified as VUS-possibly pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.37
BayesDel_addAF	Pathogenic	0.32	D
BayesDel_noAF	Pathogenic	0.40
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.66	D;.;.;T;.
Eigen	Pathogenic	0.87
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D;D;D;D;D
M_CAP	Pathogenic	0.74	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D
MetaSVM	Pathogenic	0.81	D
MutationAssessor	Uncertain	2.5	M;.;.;.;M
PrimateAI	Uncertain	0.71	T
PROVEAN	Benign	-1.6	N;.;.;N;.
REVEL	Pathogenic	0.82
Sift	Benign	0.072	T;.;.;T;.
Sift4G	Pathogenic	0.0	D;.;.;D;.
Polyphen		1.0	D;.;.;.;.
Vest4		0.96
MutPred		0.91		Loss of catalytic residue at I125 (P = 0.2968);Loss of catalytic residue at I125 (P = 0.2968);Loss of catalytic residue at I125 (P = 0.2968);Loss of catalytic residue at I125 (P = 0.2968);Loss of catalytic residue at I125 (P = 0.2968);
MVP		1.0
MPC		0.012
ClinPred		0.72	D
GERP RS		5.7
Varity_R		0.74
gMVP		0.95

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		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: rs397508606; hg19: chr7-117171055;