rs397515777

Positions:

• chr15-48495489-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 5P and 1B. PM1 PM2 PP2 BP4

The NM_000138.5(FBN1):​c.2519C>T​(p.Pro840Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,678 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/18 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P840Q) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.97

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 Uncertain_significance. Variant got 4 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 8 uncertain in NM_000138.5
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, FBN1
• BP4: Computational evidence support a benign effect (MetaRNN=0.3412615).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
FBN1	NM_000138.5	c.2519C>T	p.Pro840Leu	missense_variant	21/66	ENST00000316623.10
FBN1	NM_001406716.1	c.2519C>T	p.Pro840Leu	missense_variant	20/65

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
FBN1	ENST00000316623.10	c.2519C>T	p.Pro840Leu	missense_variant	21/66	1	NM_000138.5	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461678 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727144

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: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Mar 26, 2012

The Pro840Leu variant (FBN1) has not been reported in the literature nor previou sly identified by our laboratory. This amino acid residue is not conserved acro ss mammals (orangutan has an alanine at this position) suggesting a change at th is position could be tolerated and computational analyses (biochemical amino aci d properties, conservation, AlignGVGD, PolyPhen2, and SIFT) do not provide stron g support for or against an impact to the protein. However, this information is not predictive enough to rule out pathogenicity. Therefore, additional informat ion is needed to fully assess the clinical significance of the Pro840Leu variant . -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.10
BayesDel_addAF	Benign	-0.065	T
BayesDel_noAF	Benign	-0.33
CADD	Benign	23
DANN	Uncertain	0.99
Eigen	Benign	-0.086
Eigen_PC	Benign	0.13
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Uncertain	0.88	D
M_CAP	Benign	0.028	D
MetaRNN	Benign	0.34	T
MetaSVM	Benign	-0.40	T
MutationTaster	Benign	1.0	D
PrimateAI	Benign	0.45	T
PROVEAN	Uncertain	-2.7	D
REVEL	Uncertain	0.32
Sift	Uncertain	0.015	D
Sift4G	Benign	0.075	T
Vest4		0.41
MutPred		0.48		Loss of disorder (P = 0.0381);
MVP		0.61
MPC		1.1
ClinPred		0.59	D
GERP RS		5.9

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		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: rs397515777; hg19: chr15-48787686;