15-48644687-T-C

Variant names:

• chr15-48644687-T-C
• rs193922245
• NM_000138.5:c.83A>G

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 1P and 3B. PP2 BP4_Moderate BP6

The NM_000138.5(FBN1):​c.83A>G​(p.Asn28Ser) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000855 in 1,614,070 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/19 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. N28D) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000046 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000090 (0 hom.)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:6 B:2
• Conservation: PhyloP100: 1.70
• Publications: 7 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 -2 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=0.10846728).
• BP6: Variant 15-48644687-T-C is Benign according to our data. Variant chr15-48644687-T-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 36130.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
FBN1	NM_000138.5	c.83A>G	p.Asn28Ser	missense_variant	Exon 2 of 66	ENST00000316623.10	NP_000129.3
FBN1	NM_001406716.1	c.83A>G	p.Asn28Ser	missense_variant	Exon 1 of 65		NP_001393645.1
FBN1	NM_001406717.1	c.83A>G	p.Asn28Ser	missense_variant	Exon 2 of 9		NP_001393646.1
FBN1	NM_001406718.1	c.83A>G	p.Asn28Ser	missense_variant	Exon 2 of 3		NP_001393647.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
FBN1	ENST00000316623.10	c.83A>G	p.Asn28Ser	missense_variant	Exon 2 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: 0.0000723

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000196

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: 0.0000147

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000477 AC: 12 AN: 251478 AF XY: 0.0000441

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000289

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000791

Gnomad OTH exome AF: 0.000163

GnomAD4 exome AF: 0.0000896 AC: 131 AN: 1461876 Hom.: 0 Cov.: 30 AF XY: 0.0000756 AC XY: 55 AN XY: 727236

African (AFR) AF: 0.0000896 AC: 3 AN: 33480

American (AMR) AF: 0.0000671 AC: 3 AN: 44724

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53406

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

European-Non Finnish (NFE) AF: 0.000112 AC: 125 AN: 1112010

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome AF: 0.0000460 AC: 7 AN: 152194 Hom.: 0 Cov.: 33 AF XY: 0.0000403 AC XY: 3 AN XY: 74356

African (AFR) AF: 0.0000723 AC: 3 AN: 41468

American (AMR) AF: 0.000196 AC: 3 AN: 15292

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 5168

South Asian (SAS) AF: 0.00 AC: 0 AN: 4830

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10626

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 314

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 68024

Other (OTH) AF: 0.00 AC: 0 AN: 2090

Alfa AF: 0.0000646 Hom.: 0

Bravo AF: 0.0000264

ExAC AF: 0.0000659 AC: 8

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:6 Benign:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Familial thoracic aortic aneurysm and aortic dissection Uncertain:2

Feb 08, 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 28 of the FBN1 protein. Computational prediction tool suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). To our knowledge, functional studies have not been performed for this variant. This variant has been reported in an individual affected with sudden unexplained death (PMID: 27930701). This variant has been identified in 13/282862 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. -

Nov 08, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.N28S variant (also known as c.83A>G), located in coding exon 1 of the FBN1 gene, results from an A to G substitution at nucleotide position 83. The asparagine at codon 28 is replaced by serine, an amino acid with highly similar properties. This amino acid position is well conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Based on the available evidence, the clinical significance of this variant remains unclear. -

not provided Uncertain:1 Benign:1

Jul 09, 2024

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

May 19, 2022

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Has been previously reported in a 36 year-old female with sudden unexplained death who also harbored a second cardiogenetic variant in the PKP2 gene (Sanchez et al., 2016).; 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: 27930701, 27906200) -

not specified Uncertain:1

Jul 22, 2024

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.83A>G (p.Asn28Ser) 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 4.8e-05 in 251478 control chromosomes, predominantly at a frequency of 7.9e-05 within the Non-Finnish European subpopulation in the gnomAD database. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.83A>G has been reported in the literature in individuals affected with suddenly death and Marfan syndrome (Sanchez_2016, Groth_2017). These report(s) 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. The following publications have been ascertained in the context of this evaluation (PMID: 27906200, 27930701). ClinVar contains an entry for this variant (Variation ID: 36130). Based on the evidence outlined above, the variant was classified as uncertain significance. -

Marfan syndrome Uncertain:1

Jan 11, 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 28 of the FBN1 protein. Computational prediction tool suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <=0.5, PMID: 27666373). To our knowledge, functional studies have not been performed for this variant. This variant has not been reported in individuals affected with cardiovascular disorders in the literature. This variant has been identified in 13/282862 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. -

Marfan syndrome;C0265287:Acromicric dysplasia;C1858556:MASS syndrome;C1861456:Stiff skin syndrome;C1869115:Weill-Marchesani syndrome 2, dominant;C3280054:Geleophysic dysplasia 2;C3541518:Ectopia lentis 1, isolated, autosomal dominant;C4310796:Progeroid and marfanoid aspect-lipodystrophy syndrome Uncertain:1

Jul 27, 2021

Fulgent Genetics, Fulgent Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

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

Aug 13, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.062
BayesDel_addAF	Benign	-0.21	T
BayesDel_noAF	Benign	-0.35
CADD	Benign	18
DANN	Benign	0.82
DEOGEN2	Benign	0.36	.;T
Eigen	Benign	-0.47
Eigen_PC	Benign	-0.26
FATHMM_MKL	Benign	0.49	N
LIST_S2	Uncertain	0.88	D;D
M_CAP	Benign	0.054	D
MetaRNN	Benign	0.11	T;T
MetaSVM	Benign	-0.96	T
PhyloP100		1.7
PrimateAI	Uncertain	0.52	T
PROVEAN	Benign	-0.40	N;D
REVEL	Benign	0.060
Sift	Benign	0.87	T;D
Sift4G	Benign	0.84	T;T
Vest4		0.23
MutPred		0.37		Gain of glycosylation at N28 (P = 0.035);Gain of glycosylation at N28 (P = 0.035);
MVP		0.60
MPC		0.42
ClinPred		0.034	T
GERP RS		3.8
Mutation Taster		=85/15	polymorphism

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

Other links and lift over

dbSNP: rs193922245; hg19: chr15-48936884;