15-48520716-G-C

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1 PM2 PP2 PP3_Strong

The NM_000138.5(FBN1):c.1090C>G(p.Arg364Gly) 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 Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R364Q) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.27

Genes affected

FBN1 (HGNC:3603): (fibrillin 1) This gene encodes a member of the fibrillin family of proteins. The encoded preproprotein is proteolytically processed to generate two proteins including the extracellular matrix component fibrillin-1 and the protein hormone asprosin. Fibrillin-1 is an extracellular matrix glycoprotein that serves as a structural component of calcium-binding microfibrils. These microfibrils provide force-bearing structural support in elastic and nonelastic connective tissue throughout the body. Asprosin, secreted by white adipose tissue, has been shown to regulate glucose homeostasis. Mutations in this gene are associated with Marfan syndrome and the related MASS phenotype, as well as ectopia lentis syndrome, Weill-Marchesani syndrome, Shprintzen-Goldberg syndrome and neonatal progeroid syndrome. [provided by RefSeq, Apr 2016]

ACMG classification

Verdict is Likely_pathogenic. Variant got 9 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 8 uncertain in NM_000138.5
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, FBN1
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.967

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
FBN1	NM_000138.5	c.1090C>G	p.Arg364Gly	missense_variant	10/66	ENST00000316623.10
FBN1	NM_001406716.1	c.1090C>G	p.Arg364Gly	missense_variant	9/65

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
FBN1	ENST00000316623.10	c.1090C>G	p.Arg364Gly	missense_variant	10/66	1	NM_000138.5	P1
FBN1	ENST00000559133.6	c.1090C>G	p.Arg364Gly	missense_variant, NMD_transcript_variant	10/67	1
FBN1	ENST00000674301.2	c.1090C>G	p.Arg364Gly	missense_variant, NMD_transcript_variant	10/68
FBN1	ENST00000537463.6	c.636+16995C>G		intron_variant, NMD_transcript_variant		5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Familial thoracic aortic aneurysm and aortic dissection Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Color Diagnostics, LLC DBA Color Health

Feb 21, 2019

Variant of Uncertain Significance due to insufficient evidence: This missense variant replaces arginine with glycine at codon 364 of the FBN1 protein. Computational prediction tools and conservation analyses suggest that this variant may have deleterious impact on the protein function. Computational splicing tools suggest that this variant may not impact RNA splicing. To our knowledge, functional assays have not been performed for this variant nor has this variant been reported in individuals affected with cardiovascular disorders in the literature. This variant is rare in the general population and has been identified in 0/277264 chromosomes by the Genome Aggregation Database (gnomAD). Available evidence is insufficient to determine the role of this variant in disease conclusively. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.74
BayesDel_addAF	Pathogenic	0.47	D
BayesDel_noAF	Pathogenic	0.43
Cadd	Benign	22
Dann	Uncertain	1.0
Eigen	Uncertain	0.34
Eigen_PC	Uncertain	0.29
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.89	D
M_CAP	Pathogenic	0.75	D
MetaRNN	Pathogenic	0.97	D
MetaSVM	Uncertain	0.77	D
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.60	T
PROVEAN	Pathogenic	-5.7	D
REVEL	Pathogenic	0.85
Sift	Uncertain	0.0030	D
Sift4G	Uncertain	0.0050	D
Vest4		0.80
MutPred		0.81		Gain of sheet (P = 0.1945);
MVP		0.98
MPC		1.5
ClinPred		1.0	D
GERP RS		3.5

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: rs794728165; hg19: chr15-48812913;