chr15-48427768-G-C

Position:

• chr15-48427768-G-C

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP2 PP3_Moderate PP5

The NM_000138.5(FBN1):​c.7003C>G​(p.Arg2335Gly) 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 Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 32)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 3.69

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.

• 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, 0.887
• PP5: Variant 15-48427768-G-C is Pathogenic according to our data. Variant chr15-48427768-G-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 495643.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
FBN1	NM_000138.5	c.7003C>G	p.Arg2335Gly	missense_variant	58/66	ENST00000316623.10	NP_000129.3
FBN1	NM_001406716.1	c.7003C>G	p.Arg2335Gly	missense_variant	57/65		NP_001393645.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
FBN1	ENST00000316623.10	c.7003C>G	p.Arg2335Gly	missense_variant	58/66	1	NM_000138.5	ENSP00000325527	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

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

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jul 13, 2023

This sequence change replaces arginine, which is basic and polar, with glycine, which is neutral and non-polar, at codon 2335 of the FBN1 protein (p.Arg2335Gly). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with FBN1-related conditions (Invitae). ClinVar contains an entry for this variant (Variation ID: 495643). 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. This variant disrupts the p.Arg2335 amino acid residue in FBN1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 12203992, 29357934; Invitae). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Sep 07, 2016

Variant summary: The FBN1 c.7003C>G (p.Arg2335Gly) variant involves the alteration of a conserved nucleotide. 3/4 in silico tools predict a damaging outcome for this variant. The variant lies in EGF-like calcium-binding domain; Cys substitution is known to be deleterious in such domains. Another missense change at the same residue, p.Arg2335Trp, has been reported in patients with Marfan syndrome in literature and is classified as pathogenic by a lab in ClinVar. This variant is absent in 116790 control chromosomes from ExAC. The variant of interest has not, to our knowledge, been reported in affected individuals via publications and/or reputable databases/clinical diagnostic laboratories, nor evaluated for functional impact by in vivo/vitro studies. Because of the absence of clinical information and the lack of functional studies, the variant is currently classified as a variant of uncertain significance (VUS) until additional information becomes available. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.38	D
BayesDel_noAF	Pathogenic	0.31
CADD	Pathogenic	26
DANN	Uncertain	0.99
Eigen	Uncertain	0.49
Eigen_PC	Uncertain	0.53
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Uncertain	0.95	D
M_CAP	Pathogenic	0.51	D
MetaRNN	Pathogenic	0.89	D
MetaSVM	Uncertain	0.54	D
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.71	T
PROVEAN	Pathogenic	-6.0	D
REVEL	Pathogenic	0.69
Sift	Uncertain	0.0030	D
Sift4G	Uncertain	0.0080	D
Vest4		0.93
MutPred		0.54		Loss of stability (P = 0.0487);
MVP		0.96
MPC		1.2
ClinPred		1.0	D
GERP RS		5.4

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: rs794728262; hg19: chr15-48719965;