15-48412564-C-T

Variant names:

• chr15-48412564-C-T
• rs193922243
• NM_000138.5:c.8226+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.8226+5G>A variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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: 33)
• 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:2
• Conservation: PhyloP100: 0.929

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, max_spliceai. No scorers claiming Uncertain. Scorers claiming Benign: dbscSNV1_RF.
• PP5: Variant 15-48412564-C-T is Pathogenic according to our data. Variant chr15-48412564-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 200129.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.8226+5G>A		splice_region_variant, intron_variant	Intron 65 of 65	ENST00000316623.10	NP_000129.3
FBN1	NM_001406716.1	c.8226+5G>A		splice_region_variant, intron_variant	Intron 64 of 64		NP_001393645.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
FBN1	ENST00000316623.10	c.8226+5G>A		splice_region_variant, intron_variant	Intron 65 of 65	1	NM_000138.5	ENSP00000325527.5

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:1

Nov 11, 2019

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The FBN1 c.8226+5G>A variant (rs193922243) is reported in the literature in an individual affected with Marfan syndrome (Miller 2017). Familial testing of the affected individual did not find the variant in either parent, suggesting a de novo origin in this individual (Miller 2017). This variant is absent from general population databases (Exome Variant Server, Genome Aggregation Database), indicating it is not a common polymorphism. This is an intronic variant in a moderately conserved nucleotide, and computational analyses (Alamut v.2.11) predict that this variant may impact splicing by weakening the nearby canonical donor splice site. Based on available information, this variant is considered to be likely pathogenic. References: Miller KA et al. Diagnostic value of exome and whole genome sequencing in craniosynostosis. J Med Genet. 2017 Apr;54(4):260-268. -

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

Mar 02, 2020

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. Nucleotide substitutions within 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, but this prediction has not been confirmed by published transcriptional studies. This variant has been reported in individuals affected with Marfan syndrome or aortic dilatation, being described as de novo in two of them (PMID: 27884935, Invitae). ClinVar contains an entry for this variant (Variation ID: 200129). This variant is not present in population databases (ExAC no frequency). This sequence change falls in intron 65 of the FBN1 gene. It does not directly change the encoded amino acid sequence of the FBN1 protein, but it affects a nucleotide within the consensus splice site of the intron. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.79
CADD	Benign	16
DANN	Benign	0.65

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Benign	0.67
SpliceAI score (max)		0.59		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.35		Position offset: -6
DS_DL_spliceai		0.59		Position offset: 5

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

Publications

LitVar

Other links and lift over

dbSNP: rs193922243; hg19: chr15-48704761;