rs193922204

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM2PP3PP5_Very_Strong

The NM_000138.5(FBN1):c.4460-8G>A variant causes a splice region, splice polypyrimidine tract, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000186 in 1,613,774 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 2/2 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000014 ( 0 hom. )

Consequence

FBN1
NM_000138.5 splice_region, splice_polypyrimidine_tract, intron

Scores

Splicing: ADA: 0.9994

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:10

Conservation

PhyloP100: 0.547

Variant links:

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 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Pathogenic. Variant got 11 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PP3

Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. No scorers claiming Benign.

PP5

Variant 15-48468542-C-T is Pathogenic according to our data. Variant chr15-48468542-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 36075.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr15-48468542-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
FBN1	NM_000138.5 linkuse as main transcript	c.4460-8G>A		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant		ENST00000316623.10
FBN1	NM_001406716.1 linkuse as main transcript	c.4460-8G>A		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
FBN1	ENST00000316623.10 linkuse as main transcript	c.4460-8G>A		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant		1	NM_000138.5	P1

Frequencies

GnomAD3 genomes

AF:

0.00000658

AC:

AN:

152046

Hom.:

Cov.:

show subpopulations

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:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.00000398

AC:

AN:

250992

Hom.:

AF XY:

0.00000737

AC XY:

AN XY:

135650

show subpopulations

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 SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000137

AC:

AN:

1461728

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

727180

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.0000224

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

8.99e-7

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.00000658

AC:

AN:

152046

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74278

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.00000378

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:10

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Marfan syndrome

Pathogenic:5

Likely pathogenic, criteria provided, single submitter	clinical testing;curation	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Aug 18, 2011	- -
Likely pathogenic, no assertion criteria provided	clinical testing	Center for Medical Genetics Ghent, University of Ghent	Nov 07, 2017	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Aug 07, 2019	The c.4460-8G>A variant in FBN1 has been reported in at least 3 individuals with Marfan syndrome and segregated with disease in 2 affected individuals from 1 family (Loeys 2001, Pepe 2007, Stheneur 2009). It has also been identified in 0.003% (1/34574) of Latino chromosomes by gnomAD (http://gnomad.broadinstitute.org) and is reported in ClinVar (Variation ID: 36075). This variant is located in the 3' splice region. Computational tools and in vitro splicing assays (Pepe 2007) predict a splicing impact, though this information is not predictive enough to determine pathogenicity. 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: PM2, PP3, PS3_Supporting, PS4_Moderate. -
Pathogenic, criteria provided, single submitter	clinical testing	Blueprint Genetics	Nov 13, 2015	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Victorian Clinical Genetics Services, Murdoch Childrens Research Institute	May 26, 2020	Based on the classification scheme VCGS_Germline_v1.1.1, this variant is classified as likely pathogenic. Following criteria are met: 0102 - Loss-of-function is a known mechanism of disease for this gene. (N) 0104 - Dominant negative is a mechanism of disease for this gene. (N) 0107 - This gene is known to be associated with autosomal dominant disease. (N) 0210 - Splice site variant (canonical or non-canonical) proven to affect splicing/expression of the transcript with a known effect on protein structure. This variant has been confirmed by reverse transcriptase PCR (RT-PCR) to activate a cryptic acceptor splice site resulting in an insertion of six intronic nucleotides in exon 36 (c.4459_4460insTTTTAG). The variant results in an in-frame insertion of two amino acids in the protein sequence, p.(Thr1486_Asp1487insValLeu) (PMID: 18087243). (N) 0213 - In-frame insertion in a non-repetitive region that has high conservation. (P) 0251 - Variant is heterozygous. (N) 0302 - Variant is present in gnomAD <0.001 for a dominant condition (1 heterozygote). (P) 0507 - Identified variant type is not compatible with in silico predictions of pathogenicity. In-frame insertion not compatible. (N) 0600 - Variant is located in an annotated domain or motif. The insertion occurs between calcium-binding, EGF-like domain 25 and 26, which are normally adjacent to each other (PDB). (N) 0708 - Comparable variants have conflicting previous evidence for pathogenicity. In-frame insertion variants in this region have been reported as likely pathogenic and as VUS in ClinVar. (N) 0801 - Strong previous evidence of pathogenicity in unrelated individuals. Five likely pathogenic and two pathogenic entries in ClinVar. Previously reported in multiple patients with Marfan syndrome and ectopia lentis (PMID: 18087243, PMID: 11700157, PMID: 19293843) (P) 0905 - No segregation evidence has been identified for this variant. (N) 1007 - No published functional evidence has been identified for this variant. (N) 1208 - Inheritance information for this variant is not currently available. (N) Legend: (P) – Pathogenic, (N) – Neutral, (B) – Benign -

not specified

Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Apr 03, 2017

- -

Familial thoracic aortic aneurysm and aortic dissection

Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Nov 10, 2019

The c.4460-8G>A intronic variant results from a G to A substitution 8 nucleotides upstream from coding exon 36 in the FBN1 gene. This variant was reported in individuals with features of Marfan syndrome (Loeys B et al. Arch. Intern. Med., 2001 Nov;161:2447-54; Loeys B et al. Hum. Mutat., 2004 Aug;24:140-6; Stheneur C et al. Eur. J. Hum. Genet., 2009 Sep;17:1121-8). In one family, this variant segregated with ectopia lentis in 3 relatives and RT-PCR analysis demonstrated an inframe insertion of 6 nucleotides due to use of a cryptic acceptor site (Pepe G et al. Mol. Vis., 2007 Nov;13:2242-7). Using four different splice site prediction tools, this alteration is predicted by ESEFinder, MaxEnt, and HSF to create a new alternate splice acceptor site, but BDGP does not predict the creation of a non-native acceptor site, nor a deleterious effect on splicing; however, direct evidence is unavailable (Desmet FO et al. Nucleic Acids Res. 2009 May;37:e67). Based on data from gnomAD, the A allele has an overall frequency of approximately <0.001% (1/250992). This nucleotide position is well conserved in available vertebrate species. Based on the majority of available evidence to date, this variant is likely to be pathogenic. -

not provided

Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Nov 26, 2021

Not observed at significant frequency in large population cohorts (Lek et al., 2016); This single nucleotide substitution occurs upstream of the natural splice acceptor site in intron 36 and creates a new cryptic splice acceptor site. Two publications independently reported that cDNA sequence analysis demonstrated the result of this variant to be in-frame insertion of 6 nucleotides into the coding sequence (c.4459_4460insTTTTAG) (Loeys et al., 2001; Pepe et al., 2007).; In silico analysis supports a deleterious effect on splicing; This variant is associated with the following publications: (PMID: 19293843, 18087243, 32679894, 11700157) -

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

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Jan 01, 2024

This sequence change falls in intron 36 of the FBN1 gene. It does not directly change the encoded amino acid sequence of the FBN1 protein. This variant is present in population databases (rs193922204, gnomAD 0.003%). This variant has been observed in individual(s) with Marfan syndrome (PMID: 11700157, 19293843; Invitae). This variant is also known as IVS35-8G>A. ClinVar contains an entry for this variant (Variation ID: 36075). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -

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

Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Center for Genomics, Ann and Robert H. Lurie Children's Hospital of Chicago

Nov 11, 2021

FBN1 NM_000138 exon 37 c.4460-8G>A: This variant has been reported in the literature in at least 3 individuals with features or a clinical suspicion of Marfan syndrome, segregating with disease in 2 affected family members (Loeys 2001 PMID:11700157, Pepe 2007 PMID:18087243, Stheneur 2009 PMID:19293843). This variant is present in 1/33572 Latino alleles in the Genome Aggregation Database (http://gnomad.broadinstitute.org/rs193922204). This variant is present in ClinVar, with several labs classifying this variant as pathogenic or likely pathogenic (Variation ID:36075). Evolutionary conservation and computational predictive tools for this variant are limited or unavailable. This variant is an intronic variant with no predicted change in the amino acid sequence but may have an unknown effect on splicing. Additional studies suggest that this variant may activate a cryptic acceptor site and impact the protein (Loeys 2001 PMID:11700157, Pepe 2007 PMID:18087243). However, further studies are needed to understand its impact. In summary, data on this variant is highly suspicious for disease, but requires further evidence for pathogenicity. Therefore, this variant classified as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.66

Cadd

Uncertain

Dann

Benign

0.56

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

0.94

SpliceAI score (max)

1.0

Details are displayed if max score is > 0.2

DS_AG_spliceai

1.0

Position offset: -2

DS_AL_spliceai

0.33

Position offset: -8

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

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over