15-48415695-C-T

Position:

• chr15-48415695-C-T

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PP4 PP2 PP3 PM2_Supporting PS4_Moderate PM1_Strong

This summary comes from the ClinGen Evidence Repository: The NM_00138 c.7892G>A, is a missense variant in FBN1 predicted to cause a substitution of a cysteine by tyrosine at amino acid 2631 (p.Cys2631Tyr). This variant was found in a proband with a clinical diagnosis of Marfan syndrome (MFS) (Internal lab data, PP4). This variant has been reported three times in ClinVar: once as pathogenic, once as likely pathogenic, and once as uncertain significance (Variation ID: 42436). This variant has also been identified in at least 2 individuals with clinical diagnosis of MFS as well as in individuals with clinical features of MFS (PMID 24793577, Invitae ClinVar, internal lab data; PS4_Mod). In one pediatric individual with MFS, this variant found to segregate in an affected sister and was found to be mosaic in the asymptomatic mother (internal lab data). This variant is not present in gnomAD (PM2_sup; https://gnomad.broadinstitute.org/ v2.1.1). This variant affects a cysteine residue in a calcium binding EGF-like domain. Cysteine residues in these domains are believed to be involved in the formation of disulfide bridges which are essential for the protein structure (PM1_strong). Computational prediction tools and conservation analysis suggest that this variant may impact the protein (REVEL: 0.976, PP3). The constraint z-score for missense variants affecting FBN1 is 8.18 (PP2; https://gnomad.broadinstitute.org/ v4.0.0)). In summary, this variant meets criteria to be classified as pathogenic for Marfan syndrome based on the ACMG/AMP criteria applied, as specified by the ClinGen FBN1 VCEP: PM1_Strong, PS4_Moderate, PM2_Sup, PP2, PP3, PP4. LINK:https://erepo.genome.network/evrepo/ui/classification/CA017451/MONDO:0007947/022

• Frequency: Genomes: not found (cov: 33)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Pathogenic reviewed by expert panel P:2 U:1
• Conservation: PhyloP100: 7.91

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 Pathogenic. Variant got 10 ACMG points.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
FBN1	NM_000138.5	c.7892G>A	p.Cys2631Tyr	missense_variant	64/66	ENST00000316623.10
FBN1	NM_001406716.1	c.7892G>A	p.Cys2631Tyr	missense_variant	63/65

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
FBN1	ENST00000316623.10	c.7892G>A	p.Cys2631Tyr	missense_variant	64/66	1	NM_000138.5	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2 Uncertain:1

Revision: reviewed by expert panel

Submissions by phenotype

Marfan syndrome Pathogenic:1

Likely pathogenic, no assertion criteria provided

clinical testing

Center for Medical Genetics Ghent, University of Ghent

Nov 07, 2017

- -

Marfan syndrome;C4707243:Familial thoracic aortic aneurysm and aortic dissection Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 03, 2023

For these reasons, this variant has been classified as Pathogenic. This variant affects a cysteine residue in the EGF-like, TGFBP or hybrid motif domains of FBN1. Cysteine residues are believed to be involved in intramolecular disulfide bridges and have been shown to be important for FBN1 protein structure (PMID: 16905551, 19349279). In addition, missense substitutions affecting cysteine residues within these domains are significantly overrepresented among patients with Marfan syndrome (PMID: 16571647, 17701892). 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) performed at Invitae indicates that this missense variant is expected to disrupt FBN1 protein function. ClinVar contains an entry for this variant (Variation ID: 42436). This missense change has been observed in individuals with Marfan syndrome (PMID: 24793577; Invitae). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces cysteine, which is neutral and slightly polar, with tyrosine, which is neutral and polar, at codon 2631 of the FBN1 protein (p.Cys2631Tyr). -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Feb 11, 2016

proposed classification - variant undergoing re-assessment, contact laboratory -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.60
CADD	Pathogenic	29
DANN	Uncertain	1.0
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Pathogenic	0.97	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	0.99	D
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.85	D
PROVEAN	Pathogenic	-8.8	D
REVEL	Pathogenic	0.98
Sift	Uncertain	0.0010	D
Sift4G	Pathogenic	0.0010	D
Vest4		0.95
MutPred		0.93		Loss of methylation at K2630 (P = 0.0127);
MVP		0.99
MPC		1.9
ClinPred		1.0	D
GERP RS		5.8

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: rs111856492; hg19: chr15-48707892;