chr15-48437919-T-C

Variant names:

• chr15-48437919-T-C
• rs794728244
• NM_000138.5:c.6164-2A>G

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1_Moderate PM2 PP5_Very_Strong

The NM_000138.5(FBN1):​c.6164-2A>G variant causes a splice acceptor, intron change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: FBN1 NM_000138.5 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 8.02

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.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.01740947 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 15-48437919-T-C is Pathogenic according to our data. Variant chr15-48437919-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 373085.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.6164-2A>G		splice_acceptor_variant, intron_variant	Intron 50 of 65	ENST00000316623.10	NP_000129.3
FBN1	NM_001406716.1	c.6164-2A>G		splice_acceptor_variant, intron_variant	Intron 49 of 64		NP_001393645.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
FBN1	ENST00000316623.10	c.6164-2A>G		splice_acceptor_variant, intron_variant	Intron 50 of 65	1	NM_000138.5	ENSP00000325527.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:1

Nov 09, 2016

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Although the c.6164-2 A>G variant has not been reported as a pathogenic variant or as a benign variant to ourknowledge, it destroys the canonical splice acceptor site in intron 50 and is predicted to cause abnormal genesplicing. This variant is predicted to lead to either an abnormal message that is subject to nonsense-mediated mRNAdecay, or to an abnormal protein product if the message is used for protein translation. Other downstream splice sitevariants in the FBN1 gene and a different pathogenic splice site variant affecting the same nucleotide (c.6164-2 A>T)have been reported in HGMD or at GeneDx in association with Marfan syndrome (Stenson et al., 2014). Furthermore,the c.6164-2 A>G variant was not observed in approximately 6,500 individuals of European and African Americanancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in thesepopulations.In summary, c.6164-2 A>G in the FBN1 gene is interpreted as a pathogenic variant. -

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

Oct 01, 2016

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects an acceptor splice site in intron 50 of the FBN1 gene. It is expected to disrupt RNA splicing and likely results in an absent or disrupted protein product. This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a FBN1-related disease. In summary, donor and acceptor splice site variants are typically loss-of-function (PMID: 16199547), and loss-of-function variants in FBN1 are known to be pathogenic (PMID: 17657824, 19293843). However, without additional functional and/or genetic data, this variant has been classified as Likely Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.32
CADD	Pathogenic	30
DANN	Uncertain	1.0
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.97
FATHMM_MKL	Pathogenic	1.0	D
GERP RS		5.4

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.95
SpliceAI score (max)		0.96		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.96		Position offset: -2

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

Publications

LitVar

Other links and lift over

dbSNP: rs794728244; hg19: chr15-48730116;