chr8-16993296-T-C

Position:

• chr8-16993296-T-C

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_019851.3(FGF20):​c.412A>G​(p.Ile138Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,458,488 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 Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: FGF20 NM_019851.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.84

Genes affected

FGF20 (HGNC:3677): (fibroblast growth factor 20) The protein encoded by this gene is a member of the fibroblast growth factor family. The fibroblast growth factors possess broad mitogenic and cell survival activities, and are involved in a variety of biological processes including embryonic development, cell growth, morphogenesis, tissue repair, tumor growth and invasion. This gene product is a secreted neurotrophic factor but lacks a typical signal peptide. It is expressed in normal brain, particularly the cerebellum, and may regulate central nervous system development and function. Homodimerization of this protein was shown to regulate its receptor binding activity and concentration gradient in the extracellular matrix. Genetic variations of this gene have been associated with Parkinson disease susceptibility. [provided by RefSeq, Oct 2009]

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.19108242).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
FGF20	NM_019851.3	c.412A>G	p.Ile138Val	missense_variant	3/3	ENST00000180166.6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
FGF20	ENST00000180166.6	c.412A>G	p.Ile138Val	missense_variant	3/3	1	NM_019851.3	P1
FGF20	ENST00000519941.1	c.118A>G	p.Ile40Val	missense_variant	2/2	5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1458488 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 725064

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 9.01e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Sep 19, 2023

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Not Available"; PolyPhen-2: "Benign"; Align-GVGD: "Not Available". The valine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect protein function. This variant has not been reported in the literature in individuals affected with FGF20-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces isoleucine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 138 of the FGF20 protein (p.Ile138Val). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.11
BayesDel_addAF	Benign	-0.18	T
BayesDel_noAF	Benign	-0.50
CADD	Benign	15
DANN	Benign	0.51
DEOGEN2	Benign	0.31	T
Eigen	Benign	-0.54
Eigen_PC	Benign	-0.27
FATHMM_MKL	Uncertain	0.83	D
LIST_S2	Benign	0.65	T
M_CAP	Benign	0.0056	T
MetaRNN	Benign	0.19	T
MetaSVM	Benign	-1.1	T
MutationAssessor	Benign	-1.7	N
MutationTaster	Benign	0.99	D
PrimateAI	Uncertain	0.51	T
PROVEAN	Benign	0.58	N
REVEL	Benign	0.063
Sift	Benign	1.0	T
Sift4G	Benign	1.0	T
Polyphen		0.0	B
Vest4		0.084
MutPred		0.39		Loss of helix (P = 0.1299);
MVP		0.15
MPC		0.0061
ClinPred		0.16	T
GERP RS		3.3
Varity_R		0.32
gMVP		0.14

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: rs1809959923; hg19: chr8-16850805; COSMIC: COSV99471479;