rs201864483

Positions:

• chr7-117603558-G-A
• chr7-117603558-G-C

Variant summary

Our verdict is Likely benign. Variant got -1 ACMG points: 4P and 5B. PM1 PM2 BP4_Strong BP6

The NM_000492.4(CFTR):​c.2684G>A​(p.Ser895Asn) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000731 in 1,613,960 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/21 in silico tools predict a benign 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. S895G) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000092 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000071 (0 hom.)
• Consequence: CFTR NM_000492.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:7 B:4
• Conservation: PhyloP100: 0.459

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 Likely_benign. Variant got -1 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 13 uncertain in NM_000492.4
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.008795202).
• BP6: Variant 7-117603558-G-A is Benign according to our data. Variant chr7-117603558-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 53543.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=3, Uncertain_significance=7, Benign=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CFTR	NM_000492.4	c.2684G>A	p.Ser895Asn	missense_variant	17/27	ENST00000003084.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CFTR	ENST00000003084.11	c.2684G>A	p.Ser895Asn	missense_variant	17/27	1	NM_000492.4	P2

Frequencies

GnomAD3 genomes AF: 0.0000920 AC: 14 AN: 152210 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00269

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.000350 AC: 88 AN: 251266 Hom.: 0 AF XY: 0.000361 AC XY: 49 AN XY: 135794

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00478

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000712 AC: 104 AN: 1461632 Hom.: 0 Cov.: 32 AF XY: 0.0000688 AC XY: 50 AN XY: 727104

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00239

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.000116

GnomAD4 genome AF: 0.0000919 AC: 14 AN: 152328 Hom.: 0 Cov.: 32 AF XY: 0.0000806 AC XY: 6 AN XY: 74486

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00270

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000740 Hom.: 0

Bravo AF: 0.000144

ExAC AF: 0.000321 AC: 39

Asia WGS AF: 0.000289 AC: 1 AN: 3478

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:7 Benign:4

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Cystic fibrosis Uncertain:2 Benign:2

Likely benign, criteria provided, single submitter	clinical testing	Ambry Genetics	Jan 22, 2021	This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -
Uncertain significance, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Jul 22, 2021	- -
Likely benign, criteria provided, single submitter	clinical testing	Invitae	Jan 21, 2024	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Counsyl	Jun 09, 2017	- -

CFTR-related disorder Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	PreventionGenetics, part of Exact Sciences	May 30, 2023	The CFTR c.2684G>A variant is predicted to result in the amino acid substitution p.Ser895Asn. This variant has been reported in patients with pancreatitis (Table 3, Palermo et al. 2016. PubMed ID: 27171515; Chang et al. 2007. PubMed ID: 17539902; Chang et al. 2015. PubMed ID: 25869325) and bronchiectasis (Guan et al. 2018. PubMed ID: 29997923). The patient discussed in Guan et al. was also homozygous for a different variant in CFTR. This variant is reported in 0.46% of alleles in individuals of East Asian descent in gnomAD (http://gnomad.broadinstitute.org/variant/7-117243612-G-A). Although we suspect that this variant may be benign, at this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -
Uncertain significance, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Apr 28, 2017	This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). Publications were found based on this search. However, the evidence from the literature, in combination with allele frequency data from public databases where available, was not sufficient to rule this variant in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -

not specified Uncertain:1 Benign:1

Benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	May 20, 2022	Variant summary: CFTR c.2684G>A (p.Ser895Asn) results in a conservative amino acid change in the encoded protein sequence. Five of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 0.00035 in 251266 control chromosomes, predominantly at a frequency of 0.0048 within the East Asian subpopulation in the gnomAD database. The variant occurs with an even higher frequency in the Other East-Asian (presumably mostly Chinese) sub population (i.e. with a frequency of 0.006), and although this frequency is not higher than the estimated maximum expected for a pathogenic variant in CFTR causing Cystic Fibrosis (CF) in the Caucasian population (0.013), however, in a recent study the estimated Chinese CF prevalence was reported to be about 40x lower than the prevalence in Caucasians (Ni_2022), suggesting that the variant is a benign polymorphism found primarily in populations of East Asian origin. The variant, c.2684G>A, has been reported in the literature in four Chinese individuals affected with Cystic Fibrosis (Wu_2000, Alper_2003, Wang_2019, Yang_2021), however, in all of these patients the variant occurred in cis with a pathogenic variant (c.2083dupG (p.Glu695fs)), and all patients also carried a pathogenic variant (c.1898+5G>T) in trans, therefore these co-occurrences with other pathogenic variants provide supporting evidence for a benign role. The variant was also reported in two Chinese patients affected with congenital absence of vas deferens (CAVD; Luo_2021), however one of these patients also carried the variant c.2083dupG (p.Glu695fs) which was described earlier in cis in four Chinese CF patients, while the other patient carried two (potentially) pathogenic variants which could explain the phenotype (though the phase was not specified). In addition, the variant was published in heterozygous state in individuals affected with pancreatitis (Chang_2015, Palermo_2016) and bronchiectasis (Guan_2018), but was also found in healthy subject with a similar frequency (Guan_2018). To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Seven submitters have provided clinical-significance assessments for this variant in ClinVar after 2014 without evidence for independent evaluation, and classified the variant as VUS (n=5) or likely benign (n=2). Based on the evidence outlined above, the variant was classified as benign. -
Uncertain significance, criteria provided, single submitter	clinical testing	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Mar 09, 2017	- -

Hereditary pancreatitis Uncertain:1

Uncertain significance, criteria provided, single submitter

curation

Sema4, Sema4

May 24, 2021

- -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Quest Diagnostics Nichols Institute San Juan Capistrano

Jul 09, 2020

- -

Breast neoplasm Benign:1

Likely benign, criteria provided, single submitter

clinical testing

ACT Genomics,

Nov 06, 2020

The allele frequency of this variant c.2684G>A (p.Ser895Asn) is 0.0026 in East Asian of gnomAD and 0.003 in East Asian in 1000 Genomes. The variant is predicted to be tolerated by both SIFT or PolyPhen2. For these reasons, this variant has been classified as Likely Benign. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.077
BayesDel_addAF	Benign	-0.32	T
BayesDel_noAF	Benign	-0.23
CADD	Benign	2.9
DANN	Benign	0.61
DEOGEN2	Uncertain	0.45	T;.;.;T;.
Eigen	Benign	-1.1
Eigen_PC	Benign	-1.0
FATHMM_MKL	Benign	0.078	N
LIST_S2	Benign	0.63	T;T;T;T;T
M_CAP	Benign	0.040	D
MetaRNN	Benign	0.0088	T;T;T;T;T
MetaSVM	Benign	-0.76	T
MutationAssessor	Benign	0.21	N;.;.;.;.
MutationTaster	Benign	1.0	N;N
PrimateAI	Benign	0.29	T
PROVEAN	Benign	0.21	N;.;.;N;.
REVEL	Uncertain	0.35
Sift	Benign	0.58	T;.;.;T;.
Sift4G	Benign	0.16	T;.;.;T;.
Polyphen		0.0	B;.;.;.;.
Vest4		0.11
MVP		0.90
MPC		0.0042
ClinPred		0.010	T
GERP RS		1.6
Varity_R		0.031
gMVP		0.57

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs201864483; hg19: chr7-117243612;