rs193922242

Variant names:

• chr15-48412576-T-C
• rs193922242
• NM_000138.5:c.8219A>G

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 1P and 4B. PP2 BP4_Strong

The NM_000138.5(FBN1):​c.8219A>G​(p.Asn2740Ser) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000421 in 1,614,056 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/19 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. N2740D) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000046 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000042 (0 hom.)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:7 B:1
• Conservation: PhyloP100: 0.566
• Publications: 5 publications found

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 Gene-Disease associations (from GenCC):

• familial thoracic aortic aneurysm and aortic dissection

  Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: ClinGen, Orphanet
• Marfan syndrome

  Inheritance: AD, AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp, ClinGen, G2P, PanelApp Australia, Orphanet, Ambry Genetics
• Acromicric dysplasia

  Inheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, Ambry Genetics
• progeroid and marfanoid aspect-lipodystrophy syndrome

  Inheritance: AD Classification: STRONG, MODERATE, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, Orphanet
• stiff skin syndrome

  Inheritance: AD Classification: STRONG, LIMITED Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
• Weill-Marchesani syndrome 2, dominant

  Inheritance: AD Classification: STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae)
• geleophysic dysplasia

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• isolated ectopia lentis

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• neonatal Marfan syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Weill-Marchesani syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• ectopia lentis 1, isolated, autosomal dominant

  Inheritance: AD Classification: LIMITED Submitted by: G2P
• Shprintzen-Goldberg syndrome

  Inheritance: AD, Unknown Classification: LIMITED, NO_KNOWN Submitted by: ClinGen, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Likely_benign. The variant received -3 ACMG points.

• PP2: Missense variant in the FBN1 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 1311 curated pathogenic missense variants (we use a threshold of 10). The gene has 112 curated benign missense variants. Gene score misZ: 5.0644 (above the threshold of 3.09). Trascript score misZ: 8.1787 (above the threshold of 3.09). GenCC associations: The gene is linked to Marfan syndrome, Weill-Marchesani syndrome 2, dominant, progeroid and marfanoid aspect-lipodystrophy syndrome, geleophysic dysplasia, Shprintzen-Goldberg syndrome, stiff skin syndrome, familial thoracic aortic aneurysm and aortic dissection, isolated ectopia lentis, ectopia lentis 1, isolated, autosomal dominant, Acromicric dysplasia, neonatal Marfan syndrome, Weill-Marchesani syndrome.
• BP4: Computational evidence support a benign effect (MetaRNN=0.03619075).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
FBN1	NM_000138.5	c.8219A>G	p.Asn2740Ser	missense_variant	Exon 65 of 66	ENST00000316623.10	NP_000129.3
FBN1	NM_001406716.1	c.8219A>G	p.Asn2740Ser	missense_variant	Exon 64 of 65		NP_001393645.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
FBN1	ENST00000316623.10	c.8219A>G	p.Asn2740Ser	missense_variant	Exon 65 of 66	1	NM_000138.5	ENSP00000325527.5

Frequencies

GnomAD3 genomes AF: 0.0000460 AC: 7 AN: 152194 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000882

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000318 AC: 8 AN: 251256 AF XY: 0.0000221

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000578

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000440

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000417 AC: 61 AN: 1461744 Hom.: 0 Cov.: 32 AF XY: 0.0000413 AC XY: 30 AN XY: 727158

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.0000447 AC: 2 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.0000580 AC: 5 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53414

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.0000450 AC: 50 AN: 1111888

Other (OTH) AF: 0.0000663 AC: 4 AN: 60376

GnomAD4 genome AF: 0.0000460 AC: 7 AN: 152312 Hom.: 0 Cov.: 33 AF XY: 0.0000403 AC XY: 3 AN XY: 74488

African (AFR) AF: 0.00 AC: 0 AN: 41580

American (AMR) AF: 0.00 AC: 0 AN: 15302

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5172

South Asian (SAS) AF: 0.000207 AC: 1 AN: 4826

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10620

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 294

European-Non Finnish (NFE) AF: 0.0000882 AC: 6 AN: 68026

Other (OTH) AF: 0.00 AC: 0 AN: 2110

Alfa AF: 0.0000884 Hom.: 0

Bravo AF: 0.0000567

ExAC AF: 0.0000247 AC: 3

Asia WGS AF: 0.000289 AC: 1 AN: 3478

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:7 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

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

Aug 14, 2019

CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Mar 06, 2025

Ambry Genetics

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Feb 09, 2024

Color Diagnostics, LLC DBA Color Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces asparagine with serine at codon 2740 of the FBN1 protein. Computational prediction tools indicate that this variant has a neutral impact on protein structure and function. To our knowledge, functional studies have not been reported for this variant. This variant been reported in one individual affected with Marfan syndrome in the literature (PMID: 24793577). This variant has been identified in 10/282658 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. -

not specified Uncertain:2

Feb 10, 2025

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

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: FBN1 c.8219A>G (p.Asn2740Ser) results in a conservative amino acid change in the encoded protein sequence. Five of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 3.2e-05 in 251256 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.8219A>G has been reported in the literature in at-least one individual suspected with Marfan Syndrome (example: Lerner-Ellis_2014). These report(s) do not provide unequivocal conclusions about association of the variant with Marfan Syndrome. One publication reports experimental evidence evaluating an impact on protein function, however, does not allow convincing conclusions about the variant effect. The following publications have been ascertained in the context of this evaluation (PMID: 24793577, 22158541). ClinVar contains an entry for this variant (Variation ID: 36126). Based on the evidence outlined above, the variant was classified as uncertain significance. -

Dec 23, 2009

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Marfan syndrome Uncertain:1

Mar 24, 2024

All of Us Research Program, National Institutes of Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces asparagine with serine at codon 2740 of the FBN1 protein. Computational prediction tools and conservation analyses suggest that this variant may not impact the protein function. Computational splicing tools suggest that this variant may not impact RNA splicing. To our knowledge, functional assays have not been performed for this variant. This variant been reported in one individual affected with Marfan syndrome in the literature (PMID: 24793577). This variant has been identified in 10/282658 chromosomes in the general population by the Genome Aggregation Database (gnomAD). 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. -

not provided Uncertain:1

Nov 03, 2022

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Reported as a variant of uncertain significance in one patient with suspected Marfan syndrome; however, this patient did not meet Ghent criteria (Lerner-Ellis et al., 2014); 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).; In silico analysis supports that this missense variant does not alter protein structure/function; This variant is associated with the following publications: (PMID: 24793577) -

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

Aug 21, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces asparagine, which is neutral and polar, with serine, which is neutral and polar, at codon 2740 of the FBN1 protein (p.Asn2740Ser). This variant is present in population databases (rs193922242, gnomAD 0.005%). This missense change has been observed in individuals with clinical features of thoracic aortic aneurysm and dissection and/or Marfan syndrome (PMID: 24793577; internal data). ClinVar contains an entry for this variant (Variation ID: 36126). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is not expected to disrupt FBN1 protein function with a negative predictive value of 95%. This variant disrupts the p.Asn2740 amino acid residue in FBN1. Other variant(s) that disrupt this residue have been observed in individuals with FBN1-related conditions (PMID: 24793577; internal data), which suggests that this may be a clinically significant amino acid residue. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.063
BayesDel_addAF	Benign	-0.25	T
BayesDel_noAF	Benign	-0.48
CADD	Benign	0.10
DANN	Benign	0.36
Eigen	Benign	-1.6
Eigen_PC	Benign	-1.6
FATHMM_MKL	Benign	0.11	N
LIST_S2	Benign	0.69	T
M_CAP	Uncertain	0.12	D
MetaRNN	Benign	0.036	T
MetaSVM	Benign	-0.88	T
PhyloP100		0.57
PrimateAI	Benign	0.26	T
PROVEAN	Benign	0.22	N
REVEL	Benign	0.12
Sift	Benign	0.75	T
Sift4G	Benign	0.74	T
Vest4		0.16
MutPred		0.21		Gain of phosphorylation at N2740 (P = 0.0137);
MVP		0.63
MPC		0.39
ClinPred		0.016	T
GERP RS		-4.6
Mutation Taster		=97/3	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs193922242; hg19: chr15-48704773; COSMIC: COSV57312659;