rs1060501032

chr15-48430802-T-C

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM1 PM2 PP2 PP3_Strong PP5

The NM_000138.5(FBN1):c.6740A>G(p.Asp2247Gly) variant causes a missense, splice region 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. 3/3 splice prediction tools predict no significant impact on normal splicing. 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, splice_region
• Scores: Splicing: ADA: 0.7093
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:3 U:2
• Conservation: PhyloP100: 8.02

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 10 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 5 uncertain in NM_000138.5
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, FBN1
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.992
• PP5: Variant 15-48430802-T-C is Pathogenic according to our data. Variant chr15-48430802-T-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 406283.We mark this variant Likely_pathogenic, oryginal submissions are: {Pathogenic=2, Likely_pathogenic=1, Uncertain_significance=1}. Variant chr15-48430802-T-C is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
FBN1	NM_000138.5	c.6740A>G	p.Asp2247Gly	missense_variant, splice_region_variant	56/66	ENST00000316623.10
FBN1	NM_001406716.1	c.6740A>G	p.Asp2247Gly	missense_variant, splice_region_variant	55/65

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
FBN1	ENST00000316623.10	c.6740A>G	p.Asp2247Gly	missense_variant, splice_region_variant	56/66	1	NM_000138.5	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:3 Uncertain:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Marfan syndrome Pathogenic:1 Uncertain:1

Likely pathogenic, criteria provided, single submitter	research	Centre of Medical Genetics, University of Antwerp	Mar 01, 2021	PM2, PS6, PP4 -
Uncertain significance, no assertion criteria provided	clinical testing	Center for Medical Genetics Ghent, University of Ghent	Nov 07, 2017	- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

CeGaT Center for Human Genetics Tuebingen

Jan 01, 2019

- -

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

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Apr 07, 2023

This missense change has been observed in individual(s) with clinical features of Marfan syndrome (PMID: 19293843, 21542060; Invitae). It has also been observed to segregate with disease in related individuals. For these reasons, this variant has been classified as Pathogenic. An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. ClinVar contains an entry for this variant (Variation ID: 406283). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces aspartic acid, which is acidic and polar, with glycine, which is neutral and non-polar, at codon 2247 of the FBN1 protein (p.Asp2247Gly). -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Sep 30, 2019

Variant summary: FBN1 c.6740A>G (p.Asp2247Gly) results in a non-conservative amino acid change located in the EGF-like domain of the encoded protein sequence. The variant is located at the first 5' nucleotide position of exon 56, therefore, could affect splicing. Five of five in-silico tools predict a damaging effect of the variant on protein function. 5/5 computational tools predict no significant impact on normal splicing. However, these predictions have yet to be confirmed by functional studies. The variant was absent in 250566 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.6740A>G has been reported in the literature in individuals affected with classic Marfan Syndrome (Baetens_2011, Stheneur_2009). However, limited available information is provided (ie, lack of co-occurrence and cosegregation data). These reports do not provide unequivocal conclusions about association of the variant with Marfan Syndrome. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Two ClinVar submissions (evaluation after 2014) cite the variant as uncertain significance. In addition, other missense variants effecting the same codon, D2247Y and D2247V, along with nearby codons, C2245G, C2245S, C2245Y, D2249G, have been reported in association with MFS via HGMD. Therefore, suggesting the region may be important for FBN1 protein function. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.60
Cadd	Pathogenic	27
Dann	Uncertain	1.0
Eigen	Pathogenic	0.79
Eigen_PC	Pathogenic	0.72
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.92	D
M_CAP	Pathogenic	0.79	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.1	D
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.62	T
PROVEAN	Pathogenic	-5.7	D
REVEL	Pathogenic	0.97
Sift	Pathogenic	0.0	D
Sift4G	Uncertain	0.011	D
Vest4		0.92
MutPred		0.92		Gain of glycosylation at K2246 (P = 0.1061);
MVP		0.99
MPC		1.6
ClinPred		1.0	D
GERP RS		6.0

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.71
dbscSNV1_RF	Benign	0.63
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: rs1060501032; hg19: chr15-48722999;