4-1803731-C-T

Variant names:

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

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PM1 PM2 PM5 PP3_Strong

The NM_000142.5(FGFR3):​c.970C>T​(p.Leu324Phe) 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 Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. L324V) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 34)
• Consequence: FGFR3 NM_000142.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.99
• Publications: 0 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
• PM5: Other missense variant is known to change same aminoacid residue: 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.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.972

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
FGFR3	NM_000142.5	c.970C>T	p.Leu324Phe	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>T	p.Leu324Phe	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: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

FGFR3-related disorder Uncertain:1

Jan 23, 2023

PreventionGenetics, part of Exact Sciences

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The FGFR3 c.970C>T variant is predicted to result in the amino acid substitution p.Leu324Phe. To our knowledge, this variant has not been reported in the literature or in a large population database (http://gnomad.broadinstitute.org), indicating it is rare. Two different missense variants affecting the same amino acid (p. Leu324His and p. Leu324Val) have been reported in individuals with hypochondroplasia (Nagahara et al. 2016. PubMed ID: 27507911; Saito et al. 2012. PubMed ID: 22302603). At this time, the clinical significance of the c.970C>T (p.Leu324Phe) variant is uncertain due to the absence of conclusive functional and genetic evidence. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.40
BayesDel_addAF	Pathogenic	0.52	D
BayesDel_noAF	Pathogenic	0.50
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.61	D;T;.
Eigen	Uncertain	0.43
Eigen_PC	Uncertain	0.35
FATHMM_MKL	Uncertain	0.89	D
LIST_S2	Uncertain	0.96	D;D;T
M_CAP	Pathogenic	0.82	D
MetaRNN	Pathogenic	0.97	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Uncertain	2.0	M;.;.
PhyloP100		6.0
PROVEAN	Uncertain	-3.3	D;D;N
REVEL	Pathogenic	0.94
Sift	Uncertain	0.0010	D;D;D
Sift4G	Uncertain	0.0030	D;D;D
Polyphen		1.0	D;D;.
Vest4		0.88
MutPred		0.83		Gain of catalytic residue at L324 (P = 0.0848);Gain of catalytic residue at L324 (P = 0.0848);.;
MVP		0.99
ClinPred		0.99	D
GERP RS		3.4
Varity_R		0.91
Mutation Taster		=12/88	disease causing

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

Other links and lift over

dbSNP: rs587778816; hg19: chr4-1805458;