rs794728203

Positions:

• chr15-48487431-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.3344A>G​(p.Asp1115Gly) 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 (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 7.32

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 17 ACMG points.

• PM1: In a domain EGF-like 17; calcium-binding (size 41) in uniprot entity FBN1_HUMAN there are 18 pathogenic changes around while only 4 benign (82%) 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). 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, 0.973
• PP5: Variant 15-48487431-T-C is Pathogenic according to our data. Variant chr15-48487431-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 200015.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr15-48487431-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.3344A>G	p.Asp1115Gly	missense_variant	28/66	ENST00000316623.10	NP_000129.3
FBN1	NM_001406716.1	c.3344A>G	p.Asp1115Gly	missense_variant	27/65		NP_001393645.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
FBN1	ENST00000316623.10	c.3344A>G	p.Asp1115Gly	missense_variant	28/66	1	NM_000138.5	ENSP00000325527.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial thoracic aortic aneurysm and aortic dissection Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Ambry Genetics	Mar 27, 2015	The p.D1115G variant (also known as c.3344A>G), located in coding exon 27 of the FBN1 gene in the cb EGF-like #13 domain, results from an A to G substitution at nucleotide position 3344. The aspartic acid at codon 1115 is replaced by glycine, an amino acid with some similar properties. This variant was first identified in an individual with classic Marfan syndrome (Tiecke F et al. Eur J Hum Genet. 2001;9(1):13-21). In addition, functional in vitro studies showed this alteration resulted in retention of the protein in the endoplasmic reticulum due to defects in protein folding caused by decreased calcium binding (Whiteman P et al. Hum Mol Genet. 2007;16(8):907-18). This variant was not reported in population based cohorts in the following databases: Database of Single Nucleotide Polymorphisms (dbSNP), NHLBI Exome Sequencing Project (ESP), and 1000 Genomes Project. In the ESP, this variant was not observed in 6494 samples (12988 alleles) with coverage at this position. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be benign by PolyPhen but deleterious by SIFT in silico analyses. Based on the majority of available evidence to date, this variant is likely to be pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario	Oct 19, 2021	- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Jun 09, 2017

The D1115G variant in the FBN1 gene has been reported in association with Marfan syndrome (Tiecke F et al., 2001; Chandra A et al., 2012). Tieke et al. reported D1115 in a 35 year-old female with scoliosis, pectus carinatum, arachnodactly, and cardiovascular features; she was diagnosed with Marfan syndrome at 13 years old (2001). Chandra et al. identified D115G in a 46 year-old female with ocular features and no cardiovascular features (2012). The D1115G variant is a non-conservative amino acid substitution because these residues differ in polarity, charge, size and/or other properties and therefore is more likely to impact secondary structure. The D1115 residue is conserved across species. D1115G is located in the calcium-binding EGF-like domain of the FBN1 gene where other variants in nearby residues (C111Y, D1113G, D1113V, C1117G, C1117Y) have been reported in association with Marfan syndrome, further supporting the functional importance of this region of the protein. Furthermore, the D1115G variants was not observed in approximately 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, D1115G in the FBN1 gene is interpreted as a disease-causing variant -

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 06, 2020

For these reasons, this variant has been classified as Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site, but this prediction has not been confirmed by published transcriptional studies. This variant has been reported to affect FBN1 protein function (PMID: 17324963). This variant has been observed in individuals affected with clinical features of Marfan syndrome (PMID: 11175294, 22736615, Invitae). In at least one individual the variant was observed to be de novo. ClinVar contains an entry for this variant (Variation ID: 200015). This variant is not present in population databases (ExAC no frequency). This sequence change replaces aspartic acid with glycine at codon 1115 of the FBN1 protein (p.Asp1115Gly). The aspartic acid residue is highly conserved and there is a moderate physicochemical difference between aspartic acid and glycine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.96
BayesDel_addAF	Pathogenic	0.52	D
BayesDel_noAF	Pathogenic	0.51
CADD	Pathogenic	28
DANN	Uncertain	1.0
Eigen	Uncertain	0.43
Eigen_PC	Uncertain	0.41
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Pathogenic	0.98	D
M_CAP	Pathogenic	0.41	D
MetaRNN	Pathogenic	0.97	D
MetaSVM	Pathogenic	0.99	D
PrimateAI	Uncertain	0.68	T
PROVEAN	Pathogenic	-5.5	D
REVEL	Pathogenic	0.88
Sift	Uncertain	0.0060	D
Sift4G	Benign	0.089	T
Vest4		0.66
MutPred		0.96		Gain of catalytic residue at I1114 (P = 0.0958);
MVP		0.98
MPC		1.4
ClinPred		0.98	D
GERP RS		5.6

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: rs794728203; hg19: chr15-48779628;