rs1555394920

Positions:

• chr15-48432941-C-G

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM2 PP2 PP3

The NM_000138.5(FBN1):​c.6664G>C​(p.Val2222Leu) variant causes a missense change. 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 Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 4.12

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 Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a disulfide_bond (size 13) in uniprot entity FBN1_HUMAN there are 8 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). 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, 0.787

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
FBN1	NM_000138.5	c.6664G>C	p.Val2222Leu	missense_variant	55/66	ENST00000316623.10	NP_000129.3
FBN1	NM_001406716.1	c.6664G>C	p.Val2222Leu	missense_variant	54/65		NP_001393645.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
FBN1	ENST00000316623.10	c.6664G>C	p.Val2222Leu	missense_variant	55/66	1	NM_000138.5	ENSP00000325527	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 22, 2017

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). This variant has not been reported in the literature in individuals with FBN1-related disease. This variant is not present in population databases (ExAC no frequency). This sequence change replaces valine with leucine at codon 2222 of the FBN1 protein (p.Val2222Leu). The valine residue is highly conserved and there is a small physicochemical difference between valine and leucine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.20
BayesDel_addAF	Pathogenic	0.23	D
BayesDel_noAF	Uncertain	0.090
CADD	Pathogenic	26
DANN	Benign	0.91
Eigen	Uncertain	0.55
Eigen_PC	Uncertain	0.60
FATHMM_MKL	Uncertain	0.89	D
LIST_S2	Benign	0.71	T
M_CAP	Uncertain	0.19	D
MetaRNN	Pathogenic	0.79	D
MetaSVM	Uncertain	0.099	D
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.80	T
PROVEAN	Benign	-0.71	N
REVEL	Uncertain	0.53
Sift	Benign	0.84	T
Sift4G	Benign	0.54	T
Vest4		0.63
MutPred		0.52		Gain of catalytic residue at V2222 (P = 0.0594);
MVP		0.86
MPC		1.4
ClinPred		0.65	D
GERP RS		6.1

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: rs1555394920; hg19: chr15-48725138;