rs794728280

Positions:

• chr15-48415671-T-C

Variant summary

Our verdict is Pathogenic. Variant got 17 ACMG points: 17P and 0B. PM1 PM2 PP2 PP3_Strong PP5_Very_Strong

The NM_000138.5(FBN1):​c.7916A>G​(p.Tyr2639Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000657 in 152,204 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:9
• Conservation: PhyloP100: 1.33

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 17 ACMG points.

• PM1: In a disulfide_bond (size 13) in uniprot entity FBN1_HUMAN there are 4 pathogenic changes around while only 0 benign (100%) in NM_000138.5
• PM2: Very rare variant in population databases, with high coverage
• 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). The gene has 1311 curated pathogenic missense variants (we use a threshold of 10). The gene has 112 curated benign missense variants. GenCC has associacion of the 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, 0.977
• PP5: Variant 15-48415671-T-C is Pathogenic according to our data. Variant chr15-48415671-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 200123.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr15-48415671-T-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
FBN1	NM_000138.5	c.7916A>G	p.Tyr2639Cys	missense_variant	64/66	ENST00000316623.10	NP_000129.3
FBN1	NM_001406716.1	c.7916A>G	p.Tyr2639Cys	missense_variant	63/65		NP_001393645.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
FBN1	ENST00000316623.10	c.7916A>G	p.Tyr2639Cys	missense_variant	64/66	1	NM_000138.5	ENSP00000325527.5

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152204 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 32

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152204 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74366

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000756

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:9

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Mayo Clinic Laboratories, Mayo Clinic	Sep 23, 2021	PP1_strong, PP2, PP3, PM1, PM2, PS4_moderate -
Likely pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Jun 01, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Jan 24, 2023	Has been identified in individuals with Marfan syndrome or FBN1-related disorders referred for genetic testing at GeneDx, and in published literature (Matyas et al., 2002; Voermans et al., 2009; Attanasio et al., 2013); Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Introduces a new cysteine residue within a calcium-binding EGF-like domain of the FBN1 gene, which may affect disulfide bonding and is predicted to alter the structure and function of the protein; cysteine substitutions in the calcium-binding EGF-like domains represent the majority of pathogenic missense changes associated with FBN1-related disorders (Collod-Beroud et al., 2003); This variant is associated with the following publications: (PMID: 19659760, 23684891, 11933199, 27146836, 20200614, 32123317, 21895641, 12938084) -

Marfan syndrome Pathogenic:2

Likely pathogenic, no assertion criteria provided	clinical testing	Center for Medical Genetics Ghent, University of Ghent	Nov 07, 2017	- -
Likely pathogenic, criteria provided, single submitter	research	Centre of Medical Genetics, University of Antwerp	Mar 01, 2021	PM2, PS5, PP4 -

Familial thoracic aortic aneurysm and aortic dissection Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario	Nov 10, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Ambry Genetics	Jul 25, 2017	The p.Y2639C pathogenic mutation (also known as c.7916A>G), located in coding exon 63 of the FBN1 gene, results from an A to G substitution at nucleotide position 7916. The tyrosine at codon 2639 is replaced by cysteine, an amino acid with highly dissimilar properties, and is located in a cbEGF-like 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 several individuals with a clinical diagnosis of Marfan syndrome (MFS) as well as in a number of MFS cohorts (Mátyás G et al. Hum. Mutat. 2002;19:443-56; Voermans Nc et al. Clin. Genet. 2009;76:25-37; Aalberts JJ et al. Neth Heart J. 2010;18:85-9; Robinson DO et al. Clin. Genet. 2012;82:223-31; Attanasio M et al. Eur J Med Genet. 2013;56:356-60). In addition, this alteration segregated with disease in a large, 4-generation Dutch pedigree and in a small Polish family (Aalberts JJ et al. Neth Heart J. 2010;18:85-9; Poninska JK et al. J Transl Med. 2016;14:115). Based on the supporting evidence, this alteration is interpreted as a disease-causing mutation. -

Marfan Syndrome/Loeys-Dietz Syndrome/Familial Thoracic Aortic Aneurysms and Dissections Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Aug 25, 2017

Variant summary: The FBN1 c.7916A>G (p.Tyr2639Cys) variant involves the alteration of a conserved amino acid residue located in the EGF-like calcium-binding domain (IPR001881) (InterPro). Cysteine residues are critical in stabilization of EGF-like domains in fibrillin, thus introducing a new cysteine residue is predicted to disturb disulphide bonding and affect protein stability (Aalberts 2010). 4/4 in silico tools predict a damaging outcome for this variant (SNPsandGO not captured due to low reliability index), however these have not been investigated by functional studies. This variant has been reported in multiple patients affected by the Marfan syndrome spectrum, with a strong family history of which many fulfilled the Ghent diagnostic criteria (Aalberts 2010, Poninska 2016). This variant is absent in 121400 control chromosomes. In addition, multiple clinical diagnostic laboratories/reputable databases classified this variant as pathogenic. Taken together, this variant is classified as 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

Sep 10, 2023

For these reasons, this variant has been classified as Pathogenic. 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: 200123). This missense change has been observed in individuals with Marfan syndrome or thoracic aortic aneurysm and dissection (PMID: 20200614, 27146836). It has also been observed to segregate with disease in related individuals. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces tyrosine, which is neutral and polar, with cysteine, which is neutral and slightly polar, at codon 2639 of the FBN1 protein (p.Tyr2639Cys). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.92
BayesDel_addAF	Pathogenic	0.41	D
BayesDel_noAF	Pathogenic	0.36
CADD	Pathogenic	26
DANN	Uncertain	1.0
Eigen	Uncertain	0.26
Eigen_PC	Uncertain	0.25
FATHMM_MKL	Uncertain	0.85	D
LIST_S2	Uncertain	0.96	D
M_CAP	Uncertain	0.25	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Uncertain	0.41	D
PrimateAI	Uncertain	0.76	T
PROVEAN	Pathogenic	-4.7	D
REVEL	Pathogenic	0.82
Sift	Uncertain	0.0030	D
Sift4G	Pathogenic	0.0010	D
Vest4		0.83
MutPred		0.89		Gain of disorder (P = 0.0294);
MVP		1.0
MPC		1.5
ClinPred		0.98	D
GERP RS		3.2

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: rs794728280; hg19: chr15-48707868;