rs1445085747

Variant names:

• chr15-48508577-C-T
• rs1445085747
• NM_000138.5:c.1837+5G>A

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PM2 PP3_Moderate PP5_Very_Strong

The NM_000138.5(FBN1):​c.1837+5G>A variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,406 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: FBN1 NM_000138.5 splice_region, intron
• Scores: Splicing: ADA: 0.9998
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:9 U:1
• Conservation: PhyloP100: 2.40

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 Pathogenic. Variant got 12 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. Scorers claiming Benign: max_spliceai.
• PP5: Variant 15-48508577-C-T is Pathogenic according to our data. Variant chr15-48508577-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 527158.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
FBN1	NM_000138.5	c.1837+5G>A		splice_region_variant, intron_variant	Intron 15 of 65	ENST00000316623.10	NP_000129.3
FBN1	NM_001406716.1	c.1837+5G>A		splice_region_variant, intron_variant	Intron 14 of 64		NP_001393645.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
FBN1	ENST00000316623.10	c.1837+5G>A		splice_region_variant, intron_variant	Intron 15 of 65	1	NM_000138.5	ENSP00000325527.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251316 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135826

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

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: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461406 Hom.: 0 Cov.: 32 AF XY: 0.00000275 AC XY: 2 AN XY: 727024

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

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: 9.00e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:9 Uncertain:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Marfan syndrome Pathogenic:2 Uncertain:1

Sep 18, 2024

All of Us Research Program, National Institutes of Health

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.1837+5G>A splice site variant in FBN1 gene, that encodes for fibrillin 1, is located in intron 15. Computational prediction tools predict that the c.1837+5G>A variant may significantly impact normal splicing (Splice AI score donor gain: 0.83, -61bp). This variant likely leads to inclusion of 66bp intronic sequence resulting in an in-frame insertion of twenty-two amino acids (PMID: 26787436, 28468757). This variant has been reported in at least ten individualas affected with Marfan syndrome (MFS) (PMID: 25652356, 26787436, 28468757). In addition, this variant has been reported in two individuals affected with ectopia lentis (PMID: 14695540, 28642162), and in one individual who fulfilled the Ghent clinical criteria of MFS (PMID: 19839986). This variant is rare (2/1613632 chromosomes; 0.0001239%) in the general population database, gnomAD (v4.1.0) and interpreted as likely pathogenic/pathogenic by multiple submitters in the ClinVar database (ID: 527158). Therefore, the c.1837+5G>A variant in the FBN1 gene is classified as likely pathogenic. -

Nov 07, 2017

Center for Medical Genetics Ghent, University of Ghent

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Mar 01, 2021

Centre of Medical Genetics, University of Antwerp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: research

PM2, PS1, PP4 -

Familial thoracic aortic aneurysm and aortic dissection Pathogenic:2

Feb 01, 2023

Color Diagnostics, LLC DBA Color Health

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant causes a G to A nucleotide substitution at the +5 position of intron 15 of the FBN1 gene. Splice site prediction tools predict that this variant may have a significant impact on RNA splicing. To our knowledge, RNA studies have not been reported for this variant. This variant has been reported in two individuals affected with Marfan syndrome and in an individual suspected of having Marfan syndrome (PMID: 9399842, 19839986, 25652356). This variant has also been reported in another two individuals affected with ectopia lentis (PMID: 14695540, 28642162). This variant has been identified in 1/251316 chromosomes in the general population by the Genome Aggregation Database (gnomAD). Based on the available evidence, this variant is classified as Likely Pathogenic. -

Oct 30, 2024

Ambry Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.1837+5G>A intronic variant results from a G to A substitution 5 nucleotides after coding exon 14 in the FBN1 gene. This alteration has been detected in one individual with a clinical diagnosis of Marfan syndrome as well as in two individuals with ectopia lentis, one of whom also had skeletal manifestations (Biggin A et al. Hum. Mutat., 2004 Jan;23:99; Hung CC et al. Ann. Hum. Genet., 2009 Nov;73:559-67; Overwater E et al. Eur J Med Genet, 2017 Sep;60:465-473). This nucleotide position is well conserved in available vertebrate species. In silico splice site analysis predicts that this alteration may weaken the native splice donor site and will result in the creation or strengthening of a novel splice donor site. This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). Based on the majority of available evidence to date, this variant is likely to be pathogenic. -

not provided Pathogenic:2

Apr 02, 2024

Mayo Clinic Laboratories, Mayo Clinic

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

PP3, PP4, PM2, PS3_supporting, PS4 -

Jul 16, 2024

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis predicts this variant may weaken or destroy the splice donor site in intron 15 and may cause abnormal gene splicing; however, in the absence of functional mRNA studies, the physiological consequence of this variant cannot be precisely determined; This variant is associated with the following publications: (PMID: 9399842, 14695540, 19839986, 28642162, 10612827, 35058154) -

Marfan Syndrome/Loeys-Dietz Syndrome/Familial Thoracic Aortic Aneurysms and Dissections Pathogenic:1

Jan 23, 2023

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

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: FBN1 c.1837+5G>A alters a nucleotide located close to a canonical splice site and therefore could affect mRNA splicing, leading to a significantly altered protein sequence. Several computational tools predict a significant impact on normal splicing: One predict the variant abolishes a 5' splicing donor site. Two predict the variant weakens a 5' donor site. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 4e-06 in 251316 control chromosomes. c.1837+5G>A has been reported in the literature in multiple individuals affected with Marfan Syndrome (Franken_2016, Franken_2017) and other related phenotypes: Dural Ectasia (Hung_2009) and Ectopia Lentis (Biggin_2004, Overwater_2017). These data indicate that the variant is very likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Six clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation and classified as VUS (n=1), Likely Pathogenic (n=4) and Pathogenic (n=1). Based on the evidence outlined above, the variant was classified as pathogenic. -

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

Dec 24, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change falls in intron 15 of the FBN1 gene. It does not directly change the encoded amino acid sequence of the FBN1 protein. It affects a nucleotide within the consensus splice site. This variant is present in population databases (no rsID available, gnomAD 0.003%). This variant has been observed in individuals with Marfan syndrome (PMID: 10612827, 14695540, 19839986, 28642162). ClinVar contains an entry for this variant (Variation ID: 527158). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). 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

Jul 03, 2021

Fulgent Genetics, Fulgent Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.43
CADD	Benign	21
DANN	Benign	0.77

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.78
SpliceAI score (max)		0.060		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: rs1445085747; hg19: chr15-48800774;