rs137854471

Positions:

• chr15-48483931-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 ENST00000316623.10(FBN1):​c.3725G>A​(p.Cys1242Tyr) 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. C1242R) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: FBN1 ENST00000316623.10 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 7.91

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 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 7 uncertain in ENST00000316623.10
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr15-48483932-A-G is described in ClinVar as [Pathogenic]. Clinvar id is 1454772.Status of the report is criteria_provided_single_submitter, 1 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 15-48483931-C-T is Pathogenic according to our data. Variant chr15-48483931-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 16429.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr15-48483931-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.3725G>A	p.Cys1242Tyr	missense_variant	31/66	ENST00000316623.10	NP_000129.3
FBN1	NM_001406716.1	c.3725G>A	p.Cys1242Tyr	missense_variant	30/65		NP_001393645.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
FBN1	ENST00000316623.10	c.3725G>A	p.Cys1242Tyr	missense_variant	31/66	1	NM_000138.5	ENSP00000325527	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Marfan syndrome Pathogenic:4

Likely 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 -
Pathogenic, no assertion criteria provided	literature only	OMIM	Jan 01, 1994	- -
Pathogenic, criteria provided, single submitter	clinical testing	Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital	-	The heterozygous variant c.3725G>A (p.Cys1242Tyr) has been identified in a proband with severe myopia, marfanoid habits, hindfoot deformity, long slender fingers, chest deformity, mitral valve prolapsed and increased arm span. This variant is present in a mutation hotspot region where 4 pathogenic variants (PM1_moderate) have been reported and 1444 missense pathogenic variants in FBN1 gene have been reported (PP2_supporting). This variant is not found in gnomAD (Aggregated) (PM2_Moderate). This has been previously reported PMID: 19002209 (PP5_very strong). -

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

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 23, 2019

For these reasons, this variant has been classified as Pathogenic. 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 has been reported to affect FBN1 protein function (PMID: 27893734). This variant has been observed to be de novo in individuals affected with Marfan syndrome (PMID: 8136837, 10486319) and has been observed in additional individuals affected with Marfan syndrome (PMID: 9401003, 19002209, 27906200). This variant is also known as C344Y in the literature. ClinVar contains an entry for this variant (Variation ID: 16429). This variant is not present in population databases (ExAC no frequency). This sequence change replaces cysteine with tyrosine at codon 1242 of the FBN1 protein (p.Cys1242Tyr). The cysteine residue is highly conserved and there is a large physicochemical difference between cysteine and tyrosine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.59
CADD	Pathogenic	32
DANN	Uncertain	1.0
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	1.0	D
M_CAP	Pathogenic	0.97	D
MetaRNN	Pathogenic	1.0	D
MetaSVM	Pathogenic	0.97	D
MutationTaster	Benign	1.0	A
PrimateAI	Pathogenic	0.94	D
PROVEAN	Pathogenic	-10	D
REVEL	Pathogenic	0.98
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0010	D
Vest4		1.0
MutPred		0.98		Gain of phosphorylation at C1242 (P = 0.0043);
MVP		1.0
MPC		1.8
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: rs137854471; hg19: chr15-48776128;