rs762400500

Positions:

• chr15-48644631-C-A
• chr15-48644631-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP2

The NM_000138.5(FBN1):​c.139G>T​(p.Gly47Cys) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. 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. G47S) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 33)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.89

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 5 ACMG points.

• PM1: In a region_of_interest Fibrillin unique N-terminal (FUN) domain (size 36) in uniprot entity FBN1_HUMAN there are 30 pathogenic changes around while only 5 benign (86%) in NM_000138.5
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, FBN1

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
FBN1	NM_000138.5	c.139G>T	p.Gly47Cys	missense_variant	2/66	ENST00000316623.10
FBN1	NM_001406716.1	c.139G>T	p.Gly47Cys	missense_variant	1/65
FBN1	NM_001406717.1	c.139G>T	p.Gly47Cys	missense_variant	2/9
FBN1	NM_001406718.1	c.139G>T	p.Gly47Cys	missense_variant	2/3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
FBN1	ENST00000316623.10	c.139G>T	p.Gly47Cys	missense_variant	2/66	1	NM_000138.5	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Aug 11, 2023

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on FBN1 protein function. ClinVar contains an entry for this variant (Variation ID: 457160). This variant has not been reported in the literature in individuals affected with FBN1-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glycine, which is neutral and non-polar, with cysteine, which is neutral and slightly polar, at codon 47 of the FBN1 protein (p.Gly47Cys). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.58
BayesDel_addAF	Pathogenic	0.26	D
BayesDel_noAF	Uncertain	0.13
CADD	Pathogenic	29
DANN	Uncertain	0.98
Eigen	Uncertain	0.60
Eigen_PC	Uncertain	0.58
FATHMM_MKL	Uncertain	0.76	D
LIST_S2	Benign	0.85	T;D
M_CAP	Uncertain	0.25	D
MetaRNN	Uncertain	0.67	D;D
MetaSVM	Uncertain	0.27	D
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.68	T
PROVEAN	Benign	-1.3	N;D
REVEL	Uncertain	0.46
Sift	Benign	0.063	T;D
Sift4G	Benign	0.075	T;D
Vest4		0.57
MutPred		0.50		Loss of MoRF binding (P = 0.0933);Loss of MoRF binding (P = 0.0933);
MVP		0.91
MPC		1.4
ClinPred		0.83	D
GERP RS		4.6

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: rs762400500; hg19: chr15-48936828;