rs146726731

chr15-48520779-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 5P and 5B. PM1 PP2 PP3_Moderate BP6 BS2

The NM_000138.5(FBN1):c.1027G>A(p.Gly343Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000205 in 1,614,140 control chromosomes in the GnomAD database, with no homozygous occurrence. 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 Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. G343G) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.00022 (0 hom., cov: 32)
  • Exomes 𝑓: 0.00020 (0 hom.)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:10 B:9
• Conservation: PhyloP100: 7.71

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 Uncertain_significance. Variant got 0 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 6 uncertain in NM_000138.5
• PP2: Missense variant where missense usually causes diseases, FBN1
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.91
• BP6: Variant 15-48520779-C-T is Benign according to our data. Variant chr15-48520779-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 161244.We mark this variant Likely_benign, oryginal submissions are: {Uncertain_significance=7, Likely_benign=9}.
• BS2: High AC in GnomAd at 34 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
FBN1	NM_000138.5	c.1027G>A	p.Gly343Arg	missense_variant	10/66	ENST00000316623.10
FBN1	NM_001406716.1	c.1027G>A	p.Gly343Arg	missense_variant	9/65

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
FBN1	ENST00000316623.10	c.1027G>A	p.Gly343Arg	missense_variant	10/66	1	NM_000138.5	P1
FBN1	ENST00000559133.6	c.1027G>A	p.Gly343Arg	missense_variant, NMD_transcript_variant	10/67	1
FBN1	ENST00000674301.2	c.1027G>A	p.Gly343Arg	missense_variant, NMD_transcript_variant	10/68
FBN1	ENST00000537463.6	c.636+16932G>A		intron_variant, NMD_transcript_variant		5

Frequencies

GnomAD3 genomes AF: 0.000223 AC: 34 AN: 152144 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000724

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000327

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000353

Gnomad OTH AF: 0.000956

GnomAD3 exomes AF: 0.000187 AC: 47 AN: 251314 Hom.: 0 AF XY: 0.000214 AC XY: 29 AN XY: 135830

Gnomad AFR exome AF: 0.000123

Gnomad AMR exome AF: 0.000434

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000327

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000255

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.000203 AC: 297 AN: 1461878 Hom.: 0 Cov.: 31 AF XY: 0.000197 AC XY: 143 AN XY: 727242

Gnomad4 AFR exome AF: 0.000149

Gnomad4 AMR exome AF: 0.000402

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.000234

Gnomad4 OTH exome AF: 0.000215

GnomAD4 genome AF: 0.000223 AC: 34 AN: 152262 Hom.: 0 Cov.: 32 AF XY: 0.000215 AC XY: 16 AN XY: 74454

Gnomad4 AFR AF: 0.0000722

Gnomad4 AMR AF: 0.000327

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000353

Gnomad4 OTH AF: 0.000946

Alfa AF: 0.000380 Hom.: 0

Bravo AF: 0.000306

TwinsUK AF: 0.000270 AC: 1

ALSPAC AF: 0.000259 AC: 1

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000233 AC: 2

ExAC AF: 0.000157 AC: 19

EpiCase AF: 0.000218

EpiControl AF: 0.000296

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:10 Benign:9

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:4

Uncertain significance, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Nov 01, 2020	- -
Uncertain significance, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Aug 24, 2023	Published in association with confirmed or suspected Marfan syndrome as well as carotid artery dissection (Tjeldhorn et al., 2006; Rand-Hendriksen et al., 2007; Viveiro et al., 2013; Tjeldhorn et al., 2015; Grond-Ginsbach et al., 2017, Becerra-Munoz et al., 2018); however, one individual was found to harbor another variant that likely contributed to the phenotype, and an affected relative of a different proband was reported to be absent for this variant; In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Does not affect a cysteine residue within a calcium-binding EGF-like domain of the FBN1 gene; cysteine substitutions in the calcium-binding EGF-like domains represent the majority of pathogenic missense changes associated with FBN1-related disorders (Collod-Beroud et al., 2003); This variant is associated with the following publications: (PMID: 25637381, 27647783, 24311428, 24941995, 26332594, 25812041, 26684006, 28254189, 29357934, 30122538, 17663468, 31008308, 26582918, 17253931, 12938084, 33910934, 35886052, 31322791) -
Uncertain significance, no assertion criteria provided	clinical testing	Genome Diagnostics Laboratory, University Medical Center Utrecht	-	- -

Marfan syndrome Uncertain:2 Benign:1

Uncertain significance, no assertion criteria provided	research	CSER _CC_NCGL, University of Washington	Jun 01, 2014	- -
Likely benign, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	May 30, 2018	This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). Publications were found based on this search. The evidence from the literature, in combination with allele frequency data from public databases where available, was sufficient to determine this variant is unlikely to cause disease. Therefore, this variant is classified as likely benign. -
Uncertain significance, criteria provided, single submitter	clinical testing	All of Us Research Program, National Institutes of Health	Feb 05, 2024	This missense variant replaces glycine with arginine at codon 343 of the FBN1 protein. Computational prediction suggests that this variant may have deleterious impact on protein structure and function (internally defined REVEL score threshold >= 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in a few individuals suspected of having Marfan syndrome (PMID: 17253931, 17663468, 24311428). This variant has been reported in an individual affected with cervical artery dissection (PMID: 31008308); this individual also carried a pathogenic variant in the COL3A1 gene. This variant has been identified in 52/282706 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -

Familial thoracic aortic aneurysm and aortic dissection Uncertain:2 Benign:1

Uncertain significance, criteria provided, single submitter	clinical testing	Ambry Genetics	Aug 24, 2022	The p.G343R variant (also known as c.1027G>A), located in coding exon 9 of the FBN1 gene, results from a G to A substitution at nucleotide position 1027. The glycine at codon 343 is replaced by arginine, an amino acid with dissimilar properties. This alteration was first reported in a cohort of 105 patients with suspected Marfan syndrome (MFS) (Tjeldhorn L et al. Genet. Test., 2006;10:258-64). Later, the same group reported that the individual carrying this alteration was diagnosed with MFS (Rand-Hendriksen S et al. Am. J. Med. Genet. A. 2007;143A:1968-77), and had increased FBN1 mRNA in fibroblasts (Tjeldhorn L et al. BMC Med. Genet. 2015;16:113). This alteration was also described in a patient with spontaneous pneumothorax and Marfanoid habitus, and was detected in two relatives reported to have MFS in another study (Viveiro C et al. BMJ Case Rep, 2013;2013; Becerra-Muñoz VM. Orphanet J Rare Dis. 2018;13(1):16). This variant co-occurred with an alteration in COL3A1 in a family with carotid artery dissection, where the current variant was absent in one affected relative (Grond-Ginsbach C et al. Eur Stroke J, 2017 Jun;2:137-143). In addition, this variant has been seen in an exome cohort, but cardiovascular history was not provided (Amendola LM et al. Genome Res., 2015 Mar;25:305-15). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -
Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Mar 20, 2023	This missense variant replaces glycine with arginine at codon 343 of the FBN1 protein. Computational prediction suggests that this variant may have deleterious impact on protein structure and function (internally defined REVEL score threshold >= 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in a few individuals suspected of having Marfan syndrome (PMID: 17253931, 17663468, 24311428). This variant has been reported in an individual affected with cervical artery dissection (PMID: 31008308); this individual also carried a pathogenic variant in the COL3A1 gene. This variant has been identified in 52/282706 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -
Likely benign, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	May 30, 2018	This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases allowed determination this variant is unlikely to cause disease. Therefore, this variant is classified as likely benign. -

not specified Uncertain:1 Benign:1

Uncertain significance, criteria provided, single submitter	clinical testing	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Oct 02, 2016	- -
Likely benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Mar 27, 2023	Variant summary: FBN1 c.1027G>A (p.Gly343Arg) results in a non-conservative amino acid change located in the TB domain (IPR017878) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 0.00019 in 251406 control chromosomes, predominantly at a frequency of 0.00043 within the Latino subpopulation in the gnomAD database. The observed variant frequency within Latino control individuals in the gnomAD database is approximately 4-fold of the estimated maximal expected allele frequency for a pathogenic variant in FBN1 causing Aortopathy phenotype (0.00011), strongly suggesting that the variant is a benign polymorphism found primarily in populations of Latino origin. c.1027G>A has been reported in the literature in individuals affected with Aortopathy or MFS without strong evidence for causality (Tjeldhorn_2006, Tjeldhorn_2015, Rand-Hendriksen_2007, Viveiro_2013, Grond-Ginsbach_2017, Becerra-Munoz_2018, Kasak_2019). These reports do not provide unequivocal conclusions about association of the variant with Aortopathy. Co-occurrence with another pathogenic variant have been reported (COL3A1 c.970G>A, p.G324S), providing supporting evidence for a benign role. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Eight (other) submitters have provided clinical-significance assessments for this variant to ClinVar after 2014, and classified it as uncertain significance (n=6) or likely benign (n=2). Based on the evidence outlined above, the variant was classified as likely benign. -

Connective tissue disorder Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Center for Human Genetics, Inc, Center for Human Genetics, Inc

Nov 01, 2016

- -

Stiff skin syndrome Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

May 30, 2018

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases allowed determination this variant is unlikely to cause disease. Therefore, this variant is classified as likely benign. -

Weill-Marchesani syndrome Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

May 30, 2018

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases allowed determination this variant is unlikely to cause disease. Therefore, this variant is classified as likely benign. -

Geleophysic dysplasia Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

May 30, 2018

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases allowed determination this variant is unlikely to cause disease. Therefore, this variant is classified as likely benign. -

Acromicric dysplasia Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

May 30, 2018

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases allowed determination this variant is unlikely to cause disease. Therefore, this variant is classified as likely benign. -

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

Likely benign, criteria provided, single submitter

clinical testing

Invitae

Jan 31, 2024

- -

Ectopia lentis 1, isolated, autosomal dominant Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

May 30, 2018

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases allowed determination this variant is unlikely to cause disease. Therefore, this variant is classified as likely benign. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.81
BayesDel_addAF	Pathogenic	0.29	D
BayesDel_noAF	Pathogenic	0.51
Cadd	Pathogenic	28
Dann	Pathogenic	1.0
Eigen	Pathogenic	0.89
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.93	D
M_CAP	Pathogenic	0.40	D
MetaRNN	Pathogenic	0.91	D
MetaSVM	Pathogenic	0.92	D
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.73	T
PROVEAN	Pathogenic	-7.0	D
REVEL	Pathogenic	0.86
Sift	Uncertain	0.0010	D
Sift4G	Uncertain	0.045	D
Vest4		0.97
MutPred		0.85		Gain of catalytic residue at G343 (P = 0.0477);
MVP		0.97
MPC		1.6
ClinPred		0.75	D
GERP RS		5.7

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.070		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: rs146726731; hg19: chr15-48812976;