15-48446795-C-T

Position:

• chr15-48446795-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.5699G>A​(p.Cys1900Tyr) 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. C1900S) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 7.63

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]

FBN1 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 19 ACMG points.

• PM1: In a disulfide_bond (size 14) in uniprot entity FBN1_HUMAN there are 6 pathogenic changes around while only 0 benign (100%) 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 chr15-48446795-C-G is described in Lovd as [Pathogenic].
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), FBN1. . Gene score misZ 5.0644 (greater than the threshold 3.09). Trascript score misZ 8.1787 (greater than threshold 3.09). GenCC has associacion of gene with MASS syndrome, Weill-Marchesani syndrome, geleophysic dysplasia, Shprintzen-Goldberg syndrome, Acromicric dysplasia, familial thoracic aortic aneurysm and aortic dissection, progeroid and marfanoid aspect-lipodystrophy syndrome, ectopia lentis 1, isolated, autosomal dominant, Marfan syndrome, Weill-Marchesani syndrome 2, dominant, isolated ectopia lentis, neonatal Marfan syndrome, stiff skin syndrome.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.995
• PP5: Variant 15-48446795-C-T is Pathogenic according to our data. Variant chr15-48446795-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 200066.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr15-48446795-C-T is described in Lovd as [Pathogenic]. Variant chr15-48446795-C-T is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
FBN1	NM_000138.5	c.5699G>A	p.Cys1900Tyr	missense_variant	47/66	ENST00000316623.10	NP_000129.3
FBN1	NM_001406716.1	c.5699G>A	p.Cys1900Tyr	missense_variant	46/65		NP_001393645.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
FBN1	ENST00000316623.10	c.5699G>A	p.Cys1900Tyr	missense_variant	47/66	1	NM_000138.5	ENSP00000325527.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Marfan syndrome Pathogenic:2

Pathogenic, no assertion criteria provided	clinical testing	Center for Medical Genetics Ghent, University of Ghent	Nov 07, 2017	- -
Pathogenic, criteria provided, single submitter	research	Centre of Medical Genetics, University of Antwerp	Mar 01, 2021	PM2, PVS2, PP4 -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Aug 14, 2014

p.Cys1900Tyr (TGT>TAT): c.5699 G>A in exon 47 of the FBN1 gene (NM_000138.4)The C1900Y mutation in the FBN1 gene has been reported in association with Marfan syndrome (Baetens M et al., 2011; Arbustini E et al., 2005; Attanasio M et al., 2008). Attanasio et al. (2008) reported one individual who met the Ghent criteria for Marfan syndrome, whose features included: pectus carinatum, pes planus, positive wrist and thumb sign, dilation of the ascending aorta, MVP, ectopia lentis and striae. Arbustini et al. (2005) described two patients with C1900Y who met the Ghent criteria for Marfan syndrome. Patient one had aortic root dilation, MVP, ectopia lentis and skeletal findings. Patient two had dural ectasia, skin, eye and skeletal findings without major cardiac findings. C1900Y results in a non-conservative amino acid substitution of Cysteine at a position that is conserved across species. Other mutations affecting the same residue (C1900F, C1900S) and mutations affecting nearby residues (C1895R, C1895Y, G1903Y, G1903R, C1905R) have been reported in association with Marfan syndrome, further supporting the functional importance of this region of the protein. Furthermore, the C1900Y mutation was not observed inapproximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations.In summary, C1900Y in the FBN1 gene is interpreted as a disease-causing mutation. The variant is found in TAAD panel(s). -

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

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Dec 13, 2023

This sequence change replaces cysteine, which is neutral and slightly polar, with tyrosine, which is neutral and polar, at codon 1900 of the FBN1 protein (p.Cys1900Tyr). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with Marfan syndrome (PMID: 16222657, 18435798, 21542060). In at least one individual the variant was observed to be de novo. ClinVar contains an entry for this variant (Variation ID: 200066). 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.Cys1900 amino acid residue in FBN1. Other variant(s) that disrupt this residue have been observed in individuals with FBN1-related conditions (PMID: 19293843, 19839986, 22772377), 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	0.57	D
BayesDel_noAF	Pathogenic	0.58
CADD	Pathogenic	30
DANN	Uncertain	1.0
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.89	D
M_CAP	Pathogenic	0.94	D
MetaRNN	Pathogenic	1.0	D
MetaSVM	Pathogenic	0.96	D
PrimateAI	Pathogenic	0.81	D
PROVEAN	Pathogenic	-10	D
REVEL	Pathogenic	0.97
Sift	Uncertain	0.0010	D
Sift4G	Pathogenic	0.0010	D
Vest4		1.0
MutPred		0.99		Loss of stability (P = 0.059);
MVP		0.99
MPC		1.9
ClinPred		1.0	D
GERP RS		6.2

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: rs794728237; hg19: chr15-48738992;