15-48437763-C-G

Variant names:

• chr15-48437763-C-G
• NM_000138.5:c.6313+5G>C

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_000138.5(FBN1):​c.6313+5G>C 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. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: FBN1 NM_000138.5 splice_region, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.27

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 Likely_pathogenic. Variant got 6 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, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
FBN1	NM_000138.5	c.6313+5G>C		splice_region_variant, intron_variant	Intron 51 of 65	ENST00000316623.10	NP_000129.3
FBN1	NM_001406716.1	c.6313+5G>C		splice_region_variant, intron_variant	Intron 50 of 64		NP_001393645.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
FBN1	ENST00000316623.10	c.6313+5G>C		splice_region_variant, intron_variant	Intron 51 of 65	1	NM_000138.5	ENSP00000325527.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Marfan syndrome Uncertain:1

Jul 20, 2021

Genetics and Molecular Pathology, SA Pathology

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This is a de novo variant in this patient (parental studies for this variant performed). RNA studies previously performed on DNA from this patient - classified as a VUS variant: The RNA studies findings confirm that this variant effect aberrant splicing, however quantitative estimates indicates the aberrant transcript (FBN1:r.6313_6314ins57) is present at the limit of detection of the assay (~10%) (ie. wildtype FBN1:r.= : aberrant FBN1:r.6313_6314ins57 transcript ratio of appx 90:10 from the total mRNA. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.40
CADD	Benign	16
DANN	Benign	0.86

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.84		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.84		Position offset: 5

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

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr15-48729960;