rs397515774

Positions:

• chr15-48495519-C-G
• chr15-48495519-C-T

Variant summary

Our verdict is Pathogenic. Variant got 23 ACMG points: 23P and 0B. PS1 PM1 PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_000138.5(FBN1):​c.2489G>C​(p.Cys830Ser) 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. Variant has been reported in ClinVar as Likely pathogenic (★★). Another nucleotide change resulting in same amino acid change has been previously reported as Likely pathogenicin ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. C830Y) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 7.90

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 23 ACMG points.

• PS1: Transcript NM_000138.5 (FBN1) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in ClinVar as 915815
• PM1: In a hotspot region, there are 2 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 chr15-48495519-C-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1792034.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• 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, 0.996
• PP5: Variant 15-48495519-C-G is Pathogenic according to our data. Variant chr15-48495519-C-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 42310.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr15-48495519-C-G is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
FBN1	NM_000138.5	c.2489G>C	p.Cys830Ser	missense_variant	21/66	ENST00000316623.10
FBN1	NM_001406716.1	c.2489G>C	p.Cys830Ser	missense_variant	20/65

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
FBN1	ENST00000316623.10	c.2489G>C	p.Cys830Ser	missense_variant	21/66	1	NM_000138.5	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Marfan syndrome Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Dec 21, 2012

The c.2489G>C (p.Cys830Ser) has not been previously identified by our laboratory , but has been reported in the Korean Mutation Database (mutation ID KM0000769) in a patient with Marfan syndrome. In addition, the same amino acid change (p.Cy s830Ser) caused by a different DNA change (c.2488T>A) has been identified in one patient with clinical features of Marfan syndrome that met Ghent criteria (Sthe neur 2009). The variant identified in this individual has not been identified in large and broad populations by the NHLBI Exome Sequencing Project (http://evs.g s.washington.edu/EVS). Computational analyses (biochemical amino acid properties , conservation, AlignGVGD, PolyPhen2, and SIFT) suggest that the Cys830Ser varia nt may impact the normal function of the protein, though this information is not predictive enough to conclusively determine pathogenicity. In addition, this va riant affects a cysteine residue; cysteine substitutions are a common finding in individuals with Marfan syndrome (Schrijver 1999). In summary, this variant is likely pathogenic, though additional studies are required to fully establish its clinical significance. -

Familial thoracic aortic aneurysm and aortic dissection Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Feb 14, 2022

The p.C830S variant (also known as c.2489G>C), located in coding exon 20 of the FBN1 gene, results from a G to C substitution at nucleotide position 2489. The cysteine at codon 830 is replaced by serine, an amino acid with dissimilar properties. 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 an individual with a clinical diagnosis of Marfan syndrome (Baudhuin LM et al. J Hum Genet, 2015 May;60:241-52). In addition, a different alteration located at the same position, resulting in the same protein change, p.C830S (c.2488T>A), has been detected in an individual reported to have classical Marfan syndrome (Stheneur C et al. Eur J Hum Genet, 2009 Sep;17:1121-8). Based on internal structural assessment, this alteration eliminates a structurally critical disulfide bond in the structurally sensitive cbEGF domain #09. This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). 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

Labcorp Genetics (formerly Invitae), Labcorp

Nov 07, 2023

This sequence change replaces cysteine, which is neutral and slightly polar, with serine, which is neutral and polar, at codon 830 of the FBN1 protein (p.Cys830Ser). 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: 42310). 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). 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	0.49	D
BayesDel_noAF	Pathogenic	0.47
CADD	Pathogenic	29
DANN	Uncertain	1.0
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.89	D
M_CAP	Pathogenic	0.82	D
MetaRNN	Pathogenic	1.0	D
MetaSVM	Pathogenic	1.1	D
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.74	T
PROVEAN	Pathogenic	-7.9	D
REVEL	Pathogenic	0.90
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Vest4		0.93
MutPred		0.99		Gain of phosphorylation at C830 (P = 0.0607);
MVP		0.99
MPC		2.4
ClinPred		1.0	D
GERP RS		5.9

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: rs397515774; hg19: chr15-48787716;