15-48446775-T-C

Position:

• chr15-48446775-T-C

Variant summary

Our verdict is Pathogenic. Variant got 19 ACMG points: 19P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_000138.5(FBN1):​c.5719A>G​(p.Asn1907Asp) 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. N1907K) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 7.96

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 19 ACMG points.

• PM1: In a disulfide_bond (size 14) in uniprot entity FBN1_HUMAN there are 6 pathogenic changes around while only 0 benign (100%) in NM_000138.5
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr15-48446773-G-C is described in Lovd as [Likely_pathogenic].
• 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, 0.98
• PP5: Variant 15-48446775-T-C is Pathogenic according to our data. Variant chr15-48446775-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 42387.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
FBN1	NM_000138.5	c.5719A>G	p.Asn1907Asp	missense_variant	47/66	ENST00000316623.10	NP_000129.3
FBN1	NM_001406716.1	c.5719A>G	p.Asn1907Asp	missense_variant	46/65		NP_001393645.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
FBN1	ENST00000316623.10	c.5719A>G	p.Asn1907Asp	missense_variant	47/66	1	NM_000138.5	ENSP00000325527.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Marfan syndrome Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Sep 07, 2021	The p.Asn1907Asp variant in FBN1 has been identified in one individual with clinical features of Marfan syndrome (LMM data). The variant was not identified in either of the parents and therefore likely occurred de novo. It was absent from large population studies. Computational prediction tools and conservation analyses suggest that this variant may impact the protein. Another variant involving this codon (p.Asn1907Lys) has been identified in individuals with Marfan syndrome and is classified as likely pathogenic by this laboratory. In summary, although additional studies are required to fully establish its clinical significance, this variant meets criteria to be classified as likely pathogenic for autosomal dominant Marfan syndrome. ACMG/AMP Criteria applied: PS4_Supporting, PM6, PM2_Supporting, PP3, PM5_Supporting. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Victorian Clinical Genetics Services, Murdoch Childrens Research Institute	Feb 02, 2022	Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as Likely pathogenic. Following criteria are met: 0103 - Dominant negative and loss of function are known mechanisms of disease in this gene and are associated with FBN1-related disease. Variants predicted to result in nonsense mediated decay cause loss of function effects, and are more commonly associated with severe Marfan syndrome (MIM#154700). Missense variants with both dominant negative and loss of function effects on protein function, are associated with Marfan syndrome and ectopia lentis (MIM#129600) (OMIM, PMID: 29357934). The exact genotype-phenotype correlation for this gene is still unclear, and is compounded by variable expressivity (PMID: 20301510). (I) 0107 - This gene is predominantly associated with autosomal dominant disease; autosomal recessive forms of Marfan syndrome have been reported infrequently (PMID: 27274304; 31950671). 0115 - Variants in this gene are known to have variable expressivity. The genotype-phenotype correlations for this gene are unclear, with single variants reported in patients with a range of phenotypes (PMID: 20301510, OMIM). (I) 0200 - Variant is predicted to result in a missense amino acid change from asparagine to aspartic acid. (I) 0251 - This variant is heterozygous. (I) 0301 - Variant is absent from gnomAD (both v2 and v3). (SP) 0501 - Missense variant consistently predicted to be damaging by multiple in silico tools or highly conserved with a major amino acid change. (SP) 0600 - Variant is located in the annotated calcium-binding EGF domain (DECIPHER). (I) 0702 - Other missense variants comparable to the one identified in this case have strong previous evidence for pathogenicity. Alternative amino acid changes to serine, lysine, and histidine, have been reported in individuals with Marfan syndrome (PMID: 17657824, PMID: 24793577, PMID: 25652356, UMD-FBN1 database, ClinVar). (SP) 0809 - Previous evidence of pathogenicity for this variant is inconclusive. This variant has been reported as a VUS in ClinVar. (I) 0905 - No published segregation evidence has been identified for this variant. (I) 1007 - No published functional evidence has been identified for this variant. (I) 1208 - Inheritance information for this variant is not currently available in this individual. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -

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

Jun 20, 2022

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. This variant disrupts the p.Asn1907 amino acid residue in FBN1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 17657824, 27906200; Invitae). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. 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. ClinVar contains an entry for this variant (Variation ID: 42387). This variant has not been reported in the literature in individuals affected with FBN1-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces asparagine, which is neutral and polar, with aspartic acid, which is acidic and polar, at codon 1907 of the FBN1 protein (p.Asn1907Asp). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.21	D
BayesDel_noAF	Uncertain	0.070
CADD	Pathogenic	28
DANN	Uncertain	1.0
Eigen	Pathogenic	0.78
Eigen_PC	Pathogenic	0.80
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D
M_CAP	Uncertain	0.18	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Pathogenic	1.1	D
PrimateAI	Pathogenic	0.81	D
PROVEAN	Pathogenic	-4.6	D
REVEL	Pathogenic	0.82
Sift	Uncertain	0.0040	D
Sift4G	Benign	0.061	T
Vest4		0.84
MutPred		0.97		Gain of phosphorylation at T1904 (P = 0.1149);
MVP		0.95
MPC		1.5
ClinPred		0.98	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: rs397515824; hg19: chr15-48738972;