rs1555397646

Positions:

• chr15-48474260-C-T

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.4205G>A​(p.Cys1402Tyr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 11/18 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. C1402R) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 7.67

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 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 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 chr15-48474261-A-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1738683.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP2: Missense variant where missense usually causes diseases, FBN1
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.996
• PP5: Variant 15-48474260-C-T is Pathogenic according to our data. Variant chr15-48474260-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 519799.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.4205G>A	p.Cys1402Tyr	missense_variant	34/66	ENST00000316623.10
FBN1	NM_001406716.1	c.4205G>A	p.Cys1402Tyr	missense_variant	33/65

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
FBN1	ENST00000316623.10	c.4205G>A	p.Cys1402Tyr	missense_variant	34/66	1	NM_000138.5	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial thoracic aortic aneurysm and aortic dissection Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Dec 05, 2017

The p.C1402Y pathogenic mutation (also known as c.4205G>A), located in coding exon 33 of the FBN1 gene, results from a G to A substitution at nucleotide position 4205. The cysteine at codon 1402 is replaced by tyrosine, an amino acid with highly dissimilar properties, and is located in the cb EGF-like #19 domain. 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 alteration has been reported in a patient with Marfan syndrome and absent from controls (Comeglio P et al. Hum. Mutat., 2001 Dec;18:546-7). In addition, alternate amino acid substitutions at this position, p.C1402W and p.C1402R, have also been detected in individuals with Marfan syndrome (Schrijver I et al. Am. J. Hum. Genet., 1999 Oct;65:1007-20; Arbustini E et al. Hum. Mutat., 2005 Nov;26:494; Pees C et al. Clin. Genet., 2014 Dec;86:552-7). Based on internal structural assessment, these alterations eliminate a structurally critical disulfide bond in cbEGF domain #19. Based on the supporting evidence, this alteration is interpreted as a disease-causing mutation. -

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

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Dec 06, 2018

This sequence change replaces cysteine with tyrosine at codon 1402 of the FBN1 protein (p.Cys1402Tyr). The cysteine residue is highly conserved and there is a large physicochemical difference between cysteine and tyrosine. For these reasons, this variant has been classified as Pathogenic. This variant disrupts the p.Cys1402 amino acid residue in FBN1. Other variant(s) that disrupt this residue have been observed in affected individuals (PMID: 27906200, 10486319), suggesting that it is a clinically significant residue. As a result, variants that disrupt this residue are likely to be causative of disease. This variant affects a cysteine residue in the EGF-like, TGFBP or hybrid motif domains 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 has been observed in individuals affected with Marfan syndrome (PMID: 11524736, Invitae). ClinVar contains an entry for this variant (Variation ID: 519799). This variant is not present in population databases (ExAC no frequency). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.59
CADD	Pathogenic	29
DANN	Uncertain	0.98
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.93
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.97	D
M_CAP	Pathogenic	0.97	D
MetaRNN	Pathogenic	1.0	D
MetaSVM	Pathogenic	0.97	D
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.86	D
PROVEAN	Pathogenic	-10	D
REVEL	Pathogenic	0.99
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Vest4		0.99
MutPred		0.97		Loss of disorder (P = 0.073);
MVP		0.99
MPC		0.85
ClinPred		1.0	D
GERP RS		5.1

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: rs1555397646; hg19: chr15-48766457;