rs1555395652

chr15-48444611-A-C

Variant summary

Our verdict is Pathogenic. Variant got 19 ACMG points: 19P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_000138.5(FBN1):c.5967T>G(p.Cys1989Trp) 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 Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. C1989F) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 0.361

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 19 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 10 uncertain in NM_000138.5
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr15-48444612-C-A is described in ClinVar as [Pathogenic]. Clinvar id is 638559.Status of the report is reviewed_by_expert_panel, 3 stars.
• PP2: Missense variant where missense usually causes diseases, FBN1
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.995
• PP5: Variant 15-48444611-A-C is Pathogenic according to our data. Variant chr15-48444611-A-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 519772.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
FBN1	NM_000138.5	c.5967T>G	p.Cys1989Trp	missense_variant	49/66	ENST00000316623.10
FBN1	NM_001406716.1	c.5967T>G	p.Cys1989Trp	missense_variant	48/65

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
FBN1	ENST00000316623.10	c.5967T>G	p.Cys1989Trp	missense_variant	49/66	1	NM_000138.5	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial thoracic aortic aneurysm and aortic dissection Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Apr 28, 2017

The p.C1989W variant (also known as c.5967T>G), located in coding exon 48 of the FBN1 gene, results from a T to G substitution at nucleotide position 5967. The cysteine at codon 1989 is replaced by tryptophan, an amino acid with highly dissimilar properties, and is located in the cbEGF-like #30 domain. Based on internal structural assessment, this alteration will disrupt a conserved disulfide with C1977 in cbEGF-like #30 domain, which is disrupted by other well characterized pathogenic alterations (Downing AK et al. Cell, 1996 May;85:597-605). The majority of FBN1 mutations identified to date have involved the substitution or generation of cysteine residues within cbEGF domains (Vollbrandt T et al. J Biol Chem. 2004;279(31):32924-32931). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the majority of available evidence to date, this variant is likely to be pathogenic. -

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

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Nov 24, 2023

This sequence change replaces cysteine, which is neutral and slightly polar, with tryptophan, which is neutral and slightly polar, at codon 1989 of the FBN1 protein (p.Cys1989Trp). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with Marfan syndrome (Invitae). ClinVar contains an entry for this variant (Variation ID: 519772). 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 with a positive predictive value of 95%. 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). This variant disrupts the p.Cys1989 amino acid residue in FBN1. Other variant(s) that disrupt this residue have been observed in individuals with FBN1-related conditions (PMID: 27906200, 33436942; Invitae), which suggests that this may be a clinically significant amino acid residue. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.51	D
BayesDel_noAF	Pathogenic	0.49
Cadd	Uncertain	23
Dann	Uncertain	0.99
Eigen	Uncertain	0.41
Eigen_PC	Uncertain	0.26
FATHMM_MKL	Uncertain	0.91	D
LIST_S2	Pathogenic	1.0	D
M_CAP	Pathogenic	0.93	D
MetaRNN	Pathogenic	1.0	D
MetaSVM	Pathogenic	1.1	D
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.74	T
PROVEAN	Pathogenic	-9.5	D
REVEL	Pathogenic	0.90
Sift	Uncertain	0.0010	D
Sift4G	Pathogenic	0.0	D
Vest4		0.97
MutPred		0.94		Loss of disorder (P = 0.0132);
MVP		0.99
MPC		1.6
ClinPred		1.0	D
GERP RS		1.2

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: rs1555395652; hg19: chr15-48736808;