Genetic Variant NM_001999.4:c.6148A>G (chr5-128300835-T-C) – ACMG Classification: Likely_benign (-6 pts)

Variant summary

Our verdict is Likely benign. Variant got -6 ACMG points: 0P and 6B. BP4_ModerateBS2

The NM_001999.4(FBN2):c.6148A>G(p.Lys2050Glu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000198 in 1,613,932 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000021 ( 0 hom. )

Consequence

FBN2
NM_001999.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:4

Conservation

PhyloP100: 2.67

Variant links:

Genes affected

FBN2 (HGNC:3604): (fibrillin 2) The protein encoded by this gene is a component of connective tissue microfibrils and may be involved in elastic fiber assembly. Mutations in this gene cause congenital contractural arachnodactyly. [provided by RefSeq, Jul 2008]

FBN2 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_benign. Variant got -6 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.17597172).

BS2

High AC in GnomAdExome4 at 31 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
FBN2	NM_001999.4 link	c.6148A>G	p.Lys2050Glu	missense_variant	Exon 48 of 65	ENST00000262464.9	NP_001990.2	P35556-1
FBN2	XM_017009228.3 link	c.5995A>G	p.Lys1999Glu	missense_variant	Exon 47 of 64		XP_016864717.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
FBN2	ENST00000262464.9 link	c.6148A>G	p.Lys2050Glu	missense_variant	Exon 48 of 65	1	NM_001999.4	ENSP00000262464.4	P35556-1
FBN2	ENST00000703783.1 link	n.2932A>G		non_coding_transcript_exon_variant	Exon 23 of 38
FBN2	ENST00000703785.1 link	n.2851A>G		non_coding_transcript_exon_variant	Exon 22 of 27

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152200

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD4 exome

AF:

0.0000212

AC:

AN:

1461732

Hom.:

Cov.:

AF XY:

0.0000193

AC XY:

AN XY:

727180

show subpopulations

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:

0.0000270

Gnomad4 OTH exome

AF:

0.0000166

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152200

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74358

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.00000756

EpiCase

AF:

0.000109

EpiControl

AF:

0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Congenital contractural arachnodactyly

Uncertain:2

Aug 10, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces lysine, which is basic and polar, with glutamic acid, which is acidic and polar, at codon 2050 of the FBN2 protein (p.Lys2050Glu). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with aortic root dilation (Invitae). ClinVar contains an entry for this variant (Variation ID: 213418). 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) performed at Invitae indicates that this missense variant is not expected to disrupt FBN2 protein function with a negative predictive value of 80%. 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. -

Feb 02, 2022

Victorian Clinical Genetics Services, Murdoch Childrens Research Institute

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as VUS-3C. Following criteria are met: 0105 - The mechanism of disease for this gene is not clearly established. However, dominant negative is a likely mechanism of disease (PMID: 31316167). (I) 0107 - This gene is associated with autosomal dominant disease. There are also rare reports of a severe form of congenital contractural arachnodactyly due to biallelic variants (PMID: 33571691). (I) 0115 - Variants in this gene are known to have variable expressivity. Intra- and interfamilial variability is well reported for this gene (PMID: 20301560). (I) 0200 - Variant is predicted to result in a missense amino acid change from lysine to glutamic acid. (I) 0251 - This variant is heterozygous. (I) 0302 - Variant is present in gnomAD (v3) <0.001 for a dominant condition (1 heterozygote, 0 homozygotes). (SP) 0503 - Missense variant consistently predicted to be tolerated by multiple in silico tools or not conserved in placental mammals with a minor amino acid change. (SB) 0600 - Variant is located in the annotated calcium-binding EGF domain (DECIPHER). (I) 0705 - No comparable missense variants have previous evidence for pathogenicity. (I) 0809 - Previous evidence of pathogenicity for this variant is inconclusive. This variant has been reported as VUS twice in ClinVar. (I) 0905 - No published segregation evidence has been identified for this variant. (I) 1007 - No published functional evidence has been identified for this variant. (I) 1208 - Inheritance information for this variant is not currently available in this individual. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -

FBN2-related disorder

Uncertain:1

Jun 28, 2024

PreventionGenetics, part of Exact Sciences

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

The FBN2 c.6148A>G variant is predicted to result in the amino acid substitution p.Lys2050Glu. To our knowledge, this variant has not been reported in the literature or in a large population database, indicating this variant is rare. At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

not provided

Uncertain:1

Nov 06, 2018

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

A variant of uncertain significance has been identified in the FBN2 gene. The K2050E variant has not been published as pathogenic or been reported as benign to our knowledge. This variant is not observed in large population cohorts (Lek et al., 2016). The K2050E variant is a non-conservative amino acid substitution, which is likely to impact secondary protein structure as these residues differ in polarity, charge, size and/or other properties. Nevertheless, in-silico analyses, including protein predictors and evolutionary conservation, support that this variant does not alter protein structure/function. In addition, although the K2050E variant is located within a calcium-binding EGF-like domain of the FBN2 gene, it does not affect a cysteine residue. Cysteine substitutions in the calcium-binding EGF-like domains represent the majority of pathogenic missense changes associated with CCA (Collod-Beroud et al., 2003; Frederic et al., 2009). -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.12

BayesDel_addAF

Benign

-0.017

BayesDel_noAF

Benign

-0.26

CADD

Benign

DANN

Uncertain

0.99

DEOGEN2

Benign

0.20

T;.;T

Eigen

Benign

-0.31

Eigen_PC

Benign

-0.057

FATHMM_MKL

Uncertain

0.92

LIST_S2

Benign

0.76

T;.;.

M_CAP

Benign

0.030

MetaRNN

Benign

0.18

T;T;T

MetaSVM

Benign

-0.66

MutationAssessor

Benign

0.56

N;.;N

PrimateAI

Uncertain

0.53

PROVEAN

Benign

0.0

N;.;N

REVEL

Benign

0.24

Sift

Benign

0.54

T;.;T

Polyphen

0.0010

B;.;B

Vest4

0.30

MutPred

0.47

Loss of methylation at K2050 (P = 0.0143);.;Loss of methylation at K2050 (P = 0.0143);

MVP

0.44

MPC

0.34

ClinPred

0.70

GERP RS

5.5

Varity_R

0.080

gMVP

0.34

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over