rs28933068

chr4-1805644-C-Achr4-1805644-C-Gchr4-1805644-C-T

Variant summary

Our verdict is Pathogenic. Variant got 26 ACMG points: 26P and 0B. PS1_Very_Strong PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_000142.5(FGFR3):c.1620C>A(p.Asn540Lys) variant causes a missense change involving the alteration of a non-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 Pathogenic (★★). Another nucleotide change resulting in same amino acid change has been previously reported as Likely pathogenicin ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. N540D) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 34)
• Consequence: FGFR3 NM_000142.5 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:28 O:1
• Conservation: PhyloP100: 3.02

Genes affected

FGFR3 (HGNC:3690): (fibroblast growth factor receptor 3) This gene encodes a member of the fibroblast growth factor receptor (FGFR) family, with its amino acid sequence being highly conserved between members and among divergent species. FGFR family members differ from one another in their ligand affinities and tissue distribution. A full-length representative protein would consist of an extracellular region, composed of three immunoglobulin-like domains, a single hydrophobic membrane-spanning segment and a cytoplasmic tyrosine kinase domain. The extracellular portion of the protein interacts with fibroblast growth factors, setting in motion a cascade of downstream signals, ultimately influencing mitogenesis and differentiation. This particular family member binds acidic and basic fibroblast growth hormone and plays a role in bone development and maintenance. Mutations in this gene lead to craniosynostosis and multiple types of skeletal dysplasia. [provided by RefSeq, Aug 2017]

ACMG classification

Verdict is Pathogenic. Variant got 26 ACMG points.

• PS1: Transcript NM_000142.5 (FGFR3) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in ClinVar as 16338
• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 3 uncertain in NM_000142.5
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr4-1805643-A-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 16344.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.99
• PP5: Variant 4-1805644-C-A is Pathogenic according to our data. Variant chr4-1805644-C-A is described in ClinVar as [Pathogenic]. Clinvar id is 16337.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr4-1805644-C-A is described in Lovd as [Pathogenic]. Variant chr4-1805644-C-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
FGFR3	NM_000142.5	c.1620C>A	p.Asn540Lys	missense_variant	12/18	ENST00000440486.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
FGFR3	ENST00000440486.8	c.1620C>A	p.Asn540Lys	missense_variant	12/18	5	NM_000142.5	P4

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 34

Alfa AF: 0.0000237 Hom.: 0

Bravo AF: 0.00000756

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:28 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:12

Pathogenic, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Blueprint Genetics	Jan 22, 2020	- -
Pathogenic, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Jun 02, 2018	- -
Pathogenic, criteria provided, single submitter	clinical testing	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Nov 03, 2019	The FGFR3 c.1620C>A; p.Asn540Lys variant (rs28933068; ClinVarID: 16337) is reported in the literature in multiple individuals affected with hypochondroplasia and achondroplasia (Bellus 1995, Deutz-Terlouw 1998, Xue 2014). Together with another variant resulting in the same amino acid change (c.1620C>G; p.Asn540Lys), these account for over 50% of all hypochondroplasia cases (Bellus 2000, Linnankivi 2012, Xue 2014). The asparagine at codon 540 is highly conserved, and functional analyses of the variant protein show significant reductions in protein expression and kinase activity (Krejci 2008, Raffioni 1998). Based on available information, this variant is considered to be pathogenic. References: Bellus GA et al. A recurrent mutation in the tyrosine kinase domain of fibroblast growth factor receptor 3 causes hypochondroplasia. Nat Genet. 1995 Jul;10(3):357-9. Bellus GA et al. Distinct missense mutations of the FGFR3 lys650 codon modulate receptor kinase activation and the severity of the skeletal dysplasia phenotype. Am J Hum Genet. 2000 Dec;67(6):1411-21. Deutz-Terlouw PP et al. Asn540Thr substitution in the fibroblast growth factor receptor 3 tyrosine kinase domain causing hypochondroplasia. Hum Mutat. 1998;Suppl 1:S62-5. Krejci P et al. Analysis of STAT1 activation by six FGFR3 mutants associated with skeletal dysplasia undermines dominant role of STAT1 in FGFR3 signaling in cartilage. PLoS One. 2008;3(12):e3961. Linnankivi T et al. Neuroimaging and neurological findings in patients with hypochondroplasia and FGFR3 N540K mutation. Am J Med Genet A. 2012 Dec;158A(12):3119-25. Raffioni S et al. Effect of transmembrane and kinase domain mutations on fibroblast growth factor receptor 3 chimera signaling in PC12 cells. A model for the control of receptor tyrosine kinase activation. J Biol Chem. 1998 Dec 25;273(52):35250-9. Xue Y et al. FGFR3 mutation frequency in 324 cases from the International Skeletal Dysplasia Registry. Mol Genet Genomic Med. 2014 Nov;2(6):497-503. -
Pathogenic, criteria provided, single submitter	clinical testing	Clinical Genetics and Genomics, Karolinska University Hospital	Aug 02, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Apr 01, 2018	- -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Mar 10, 2022	Published functional studies demonstrate this variant results in significantly reduced expression patterns and reduced STAT1 phosphorylation (Raffioni et al., 1998; Krejci et al., 2008); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 22045636, 19088846, 23165795, 19449430, 23614116, 16575888, 9452043, 9857065, 25614871, 10360393, 24630288, 23573386, 24715719, 25505998, 16222682, 16020314, 8589686, 30335613, 30138938, 29620724, 30355600, 31130284, 33942288, 30755392, 32964447, 20301650, 34006472, 33726816, 7670477) -
Pathogenic, no assertion criteria provided	clinical testing	Laboratory of Diagnostic Genome Analysis, Leiden University Medical Center (LUMC)	-	- -
Pathogenic, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Feb 01, 2022	- -
Pathogenic, criteria provided, single submitter	clinical testing	Al Jalila Children's Genomics Center, Al Jalila Childrens Speciality Hospital	Dec 17, 2022	- -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Jan 22, 2024	This sequence change replaces asparagine, which is neutral and polar, with lysine, which is basic and polar, at codon 540 of the FGFR3 protein (p.Asn540Lys). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individuals with sporadic or familial hypochondroplasia (PMID: 7670477, 8589686, 9452043, 11055896, 23165795, 25614871). It has also been observed to segregate with disease in related individuals. This variant is also known as c.1659C>A. ClinVar contains an entry for this variant (Variation ID: 16337). Advanced modeling performed at Invitae incorporating data from internal and/or published experimental studies (Invitae) indicates that this missense variant is expected to disrupt FGFR3 function with a positive predictive value of 95%. For these reasons, this variant has been classified as Pathogenic. -

Hypochondroplasia Pathogenic:9 Other:1

Pathogenic, criteria provided, single submitter	clinical testing	3billion	Feb 23, 2023	The variant is not observed in the gnomAD v2.1.1 dataset. Missense changes are a common disease-causing mechanism. In silico tool predictions suggest damaging effect of the variant on gene or gene product (REVEL: 0.69; 3Cnet: 0.72). Same nucleotide change resulting in same amino acid change has been previously reported as pathogenic/likely pathogenic with strong evidence (ClinVar ID: VCV000016337). The variant has been observed in multiple (>3) similarly affected unrelated individuals (PMID: 25614871). Different missense changes at the same codon (p.Asn540Asp, p.Asn540His, p.Asn540Ser, p.Asn540Thr) have been reported as pathogenic/likely pathogenic with strong evidence (ClinVar ID: VCV000016344, VCV000016349, VCV000374828, VCV001325830). Therefore, this variant is classified as Pathogenic according to the recommendation of ACMG/AMP guideline. -
Pathogenic, no assertion criteria provided	literature only	OMIM	Jun 11, 1999	- -
Pathogenic, criteria provided, single submitter	clinical testing	Laboratorio de Genetica e Diagnostico Molecular, Hospital Israelita Albert Einstein	Dec 03, 2021	ACMG classification criteria: PS1 strong, PS3 supporting, PS4 strong, PM2 moderate -
Pathogenic, no assertion criteria provided	clinical testing	Clinical Molecular Genetics Laboratory, Johns Hopkins All Children's Hospital	Jul 21, 2015	- -
Pathogenic, no assertion criteria provided	clinical testing	Bioscientia Institut fuer Medizinische Diagnostik GmbH, Sonic Healthcare	Jun 18, 2018	- -
Pathogenic, criteria provided, single submitter	clinical testing	Kasturba Medical College, Manipal, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India	May 09, 2022	- -
Pathogenic, no assertion criteria provided	research	Beijing Key Laboratory for Genetic Research of Skeletal Deformity, Peking Union Medical College Hospital	May 31, 2019	- -
Pathogenic, criteria provided, single submitter	clinical testing	Greenwood Genetic Center Diagnostic Laboratories, Greenwood Genetic Center	Aug 29, 2023	PS2, PS4, PM1, PM2, PM3, PP3 -
Pathogenic, criteria provided, single submitter	clinical testing	Institute of Human Genetics, University of Leipzig Medical Center	Jan 22, 2024	Criteria applied: PS4,PM5_STR,PS1,PS3_MOD,PM2_SUP,PP3,PM1_SUP -
not provided, no classification provided	literature only	GeneReviews	-	Most common pathogenic variant in hypochondroplasia -

Achondroplasia Pathogenic:5

Pathogenic, criteria provided, single submitter	clinical testing	DASA	Jan 05, 2022	The c.1620C>A;p.(Asn540Lys) missense variant has been observed in affected individual(s) and ClinVar contains an entry for this variant (Clinvar ID: 16337; PMID: 23573386; 7670477; 8589686; 25614871) - PS4. Well-established in vitro or in vivo functional studies support a damaging effect on the gene or gene product (PMID: 11055896) - PS3_supporting.Same amino acid change as a previously established pathogenic variant regardless of nucleotide change(ClinVar: 16338; PMID 23165795; 25614871) - PS1. This variant is not present in population databases (rs28933068, gnomAD; ABraOM no frequency - http://abraom.ib.usp.br/) - PM2. Pathogenic missense variant in this residue have been reported (Clinvar ID: 16349; 16344) - PM5. Multiple lines of computational evidence support a deleterious effect on the gene or gene product - PP3. In summary, the currently available evidence indicates that the variant is pathogenic. -
Pathogenic, no assertion criteria provided	clinical testing	Clinical Molecular Genetics Laboratory, Johns Hopkins All Children's Hospital	Jul 21, 2015	- -
Pathogenic, criteria provided, single submitter	clinical testing	Medical Genetics Center, Maternal and Child Health Hospital of Hubei Province	May 21, 2021	- -
Pathogenic, no assertion criteria provided	clinical testing	Clinical Laboratory Sciences Program (CLSP), King Saud bin Abdulaziz University for Health Sciences (KSAU-HS)	Apr 01, 2023	- -
Pathogenic, criteria provided, single submitter	research	Division of Human Genetics, National Health Laboratory Service/University of the Witwatersrand	Jul 01, 2023	- -

Neurodevelopmental delay Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Centre de Biologie Pathologie Génétique, Centre Hospitalier Universitaire de Lille

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FGFR3-related disorder Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

PreventionGenetics, part of Exact Sciences

Nov 09, 2023

The FGFR3 c.1620C>A variant is predicted to result in the amino acid substitution p.Asn540Lys. This variant is reported to be the most common cause of hypochondroplasia (for example see: Bellus et al. 1995. PubMed ID: 7670477; Linnankivi et al. 2012. PubMed ID: 23165795; Mustafa et al. 2014. PubMed ID: 25505998; Xue et al. 2014. PubMed ID: 25614871; Maddirevula et al. 2018. PubMed ID: 29620724). This variant has been reported in the homozygous state in a patient with severe hypochondroplasia (De Rosa et al. 2014. PubMed ID: 24715719), and has also been reported in patients with thanatophoric dysplasia as part of a complex double de novo FGFR3 allele (Pannier et al. 2009. PubMed ID: 19449430; Marquis-Nicholson et al. 2013. PubMed ID: 23573386). This variant has not been reported in a large population database (http://gnomad.broadinstitute.org), indicating this variant is rare. This variant is interpreted as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Uncertain	0.12	D
BayesDel_noAF	Uncertain	-0.060
Cadd	Uncertain	24
Dann	Uncertain	0.99
DEOGEN2	Pathogenic	0.89	D;D;.;.;.
Eigen	Benign	0.15
Eigen_PC	Benign	0.16
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Uncertain	0.94	D;D;D;D;.
M_CAP	Pathogenic	0.91	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D
MetaSVM	Uncertain	0.18	D
MutationAssessor	Benign	-0.10	N;.;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D
PrimateAI	Pathogenic	0.85	D
PROVEAN	Pathogenic	-5.3	D;D;D;D;D
REVEL	Pathogenic	0.69
Sift	Pathogenic	0.0	D;D;D;D;D
Sift4G	Uncertain	0.0020	D;D;D;D;D
Polyphen		1.0	D;D;D;D;D
Vest4		1.0
MutPred		0.90		Gain of methylation at N540 (P = 0.007);.;.;.;.;
MVP		0.95
MPC		1.0
ClinPred		1.0	D
GERP RS		3.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.97
gMVP		0.81

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		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: rs28933068; hg19: chr4-1807371;