4-1806164-G-T

Position:

• chr4-1806164-G-T

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PS1 PM1 PM2 PM5 PP3_Strong PP5_Moderate

The NM_000142.5(FGFR3):​c.1950G>T​(p.Lys650Asn) 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 Pathogenicin Lovd. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. K650E) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 34)
• Consequence: FGFR3 NM_000142.5 missense
• Clinical Significance: Pathogenic criteria provided, single submitter P:2 O:1
• Conservation: PhyloP100: 1.76

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 16 ACMG points.

• PS1: Transcript NM_000142.5 (FGFR3) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in Lovd
• PM1: In a mutagenesis_site Constitutively activated kinase. (size 0) in uniprot entity FGFR3_HUMAN there are 5 pathogenic changes around while only 0 benign (100%) 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 chr4-1806162-A-G is described in Lovd as [Pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.985
• PP5: Variant 4-1806164-G-T is Pathogenic according to our data. Variant chr4-1806164-G-T is described in ClinVar as [Pathogenic]. Clinvar id is 16346.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
FGFR3	NM_000142.5	c.1950G>T	p.Lys650Asn	missense_variant	14/18	ENST00000440486.8	NP_000133.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
FGFR3	ENST00000440486.8	c.1950G>T	p.Lys650Asn	missense_variant	14/18	5	NM_000142.5	ENSP00000414914	P4

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome Cov.: 35

GnomAD4 genome Cov.: 34

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hypochondroplasia Pathogenic:1 Other:1

not provided, no classification provided	literature only	GeneReviews	-	Milder skeletal phenotype [Bellus et al 2000] -
Pathogenic, no assertion criteria provided	literature only	OMIM	Dec 01, 2000	- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jul 08, 2023

ClinVar contains an entry for this variant (Variation ID: 16346). For these reasons, this variant has been classified as Pathogenic. This variant disrupts the p.Lys650 amino acid residue in FGFR3. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 11055896, 16912704, 20453470, 21510009). 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on FGFR3 protein function. This missense change has been observed in individuals with clinical features of hypochondroplasia (PMID: 11055896; Invitae). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces lysine, which is basic and polar, with asparagine, which is neutral and polar, at codon 650 of the FGFR3 protein (p.Lys650Asn). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Uncertain	0.081	D
BayesDel_noAF	Benign	-0.12
CADD	Uncertain	25
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.88	D;D;.;.;.
Eigen	Uncertain	0.40
Eigen_PC	Uncertain	0.32
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Uncertain	0.96	D;D;D;D;.
M_CAP	Pathogenic	0.82	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D
MetaSVM	Uncertain	0.13	D
MutationAssessor	Benign	0.61	N;.;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D
PrimateAI	Pathogenic	0.89	D
PROVEAN	Pathogenic	-4.4	D;D;D;D;D
REVEL	Pathogenic	0.66
Sift	Uncertain	0.0010	D;D;D;D;D
Sift4G	Pathogenic	0.0010	D;D;D;D;D
Polyphen		1.0	D;D;D;D;D
Vest4		0.95
MutPred		0.96		Gain of ubiquitination at K649 (P = 0.0444);.;.;.;.;
MVP		0.94
MPC		2.4
ClinPred		1.0	D
GERP RS		3.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.96
gMVP		0.83

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: rs28928868; hg19: chr4-1807891; COSMIC: COSV53408403; COSMIC: COSV53408403;