4-1803731-C-G

Variant names:

• chr4-1803731-C-G
• rs587778816
• NM_000142.5:c.970C>G

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PM1 PM2 PP3_Strong PP5_Moderate

The NM_000142.5(FGFR3):​c.970C>G​(p.Leu324Val) variant causes a missense change. 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 Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. L324F) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 34)
• Consequence: FGFR3 NM_000142.5 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 5.99
• Publications: 3 publications found

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]

FGFR3 Gene-Disease associations (from GenCC):

• achondroplasia

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, ClinGen, Genomics England PanelApp, Orphanet, Ambry Genetics, Labcorp Genetics (formerly Invitae)
• Crouzon syndrome-acanthosis nigricans syndrome

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Ambry Genetics, Orphanet, Genomics England PanelApp, Labcorp Genetics (formerly Invitae), PanelApp Australia, ClinGen
• hypochondroplasia

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Ambry Genetics, G2P, ClinGen, Labcorp Genetics (formerly Invitae), Orphanet
• lacrimoauriculodentodigital syndrome 2

  Inheritance: AD Classification: DEFINITIVE Submitted by: G2P
• Muenke syndrome

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Ambry Genetics, PanelApp Australia, Labcorp Genetics (formerly Invitae), Genomics England PanelApp, ClinGen, G2P
• thanatophoric dysplasia type 1

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Ambry Genetics, Genomics England PanelApp, Orphanet, ClinGen
• thanatophoric dysplasia type 2

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, ClinGen, Genomics England PanelApp, G2P, Labcorp Genetics (formerly Invitae)
• camptodactyly-tall stature-scoliosis-hearing loss syndrome

  Inheritance: AR, AD, SD Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE, LIMITED Submitted by: Ambry Genetics, G2P, Orphanet, Labcorp Genetics (formerly Invitae), ClinGen
• severe achondroplasia-developmental delay-acanthosis nigricans syndrome

  Inheritance: AD Classification: STRONG, MODERATE, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae), ClinGen
• isolated brachycephaly

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• isolated plagiocephaly

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• LADD syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• LADD syndrome 1

  Inheritance: AD Classification: LIMITED Submitted by: Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 11 uncertain in NM_000142.5
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.976
• PP5: Variant 4-1803731-C-G is Pathogenic according to our data. Variant chr4-1803731-C-G is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 1680048.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
FGFR3	NM_000142.5	c.970C>G	p.Leu324Val	missense_variant	Exon 8 of 18	ENST00000440486.8	NP_000133.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
FGFR3	ENST00000440486.8	c.970C>G	p.Leu324Val	missense_variant	Exon 8 of 18	5	NM_000142.5	ENSP00000414914.2

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 34

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Pathogenic:1

May 29, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces leucine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 324 of the FGFR3 protein (p.Leu324Val). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with hypochondroplasia (PMID: 22302603). In at least one individual the variant was observed to be de novo. ClinVar contains an entry for this variant (Variation ID: 1680048). 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 variant disrupts the p.Leu324 amino acid residue in FGFR3. Other variant(s) that disrupt this residue have been observed in individuals with FGFR3-related conditions (PMID: 27507911), which suggests that this may be a clinically significant amino acid residue. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.76
BayesDel_addAF	Pathogenic	0.51	D
BayesDel_noAF	Pathogenic	0.49
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.59	D;T;.
Eigen	Uncertain	0.45
Eigen_PC	Uncertain	0.37
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Pathogenic	0.99	D;D;T
M_CAP	Pathogenic	0.82	D
MetaRNN	Pathogenic	0.98	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Uncertain	2.5	M;.;.
PhyloP100		6.0
PROVEAN	Uncertain	-2.5	N;D;N
REVEL	Pathogenic	0.95
Sift	Uncertain	0.0010	D;D;D
Sift4G	Uncertain	0.038	D;D;D
Polyphen		1.0	D;D;.
Vest4		0.85
MutPred		0.85		Gain of glycosylation at S325 (P = 0.2389);Gain of glycosylation at S325 (P = 0.2389);.;
MVP		0.98
ClinPred		0.98	D
GERP RS		3.4
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.96
Mutation Taster		=2/98	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs587778816; hg19: chr4-1805458;