rs923812426

Positions:

• chr5-128393157-C-G
• chr5-128393157-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_001999.4(FBN2):​c.1443G>C​(p.Gln481His) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,728 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: FBN2 NM_001999.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: -0.0120

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.17634365).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
FBN2	NM_001999.4	c.1443G>C	p.Gln481His	missense_variant	10/65	ENST00000262464.9	NP_001990.2
FBN2	XM_017009228.3	c.1290G>C	p.Gln430His	missense_variant	9/64		XP_016864717.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
FBN2	ENST00000262464.9	c.1443G>C	p.Gln481His	missense_variant	10/65	1	NM_001999.4	ENSP00000262464.4
FBN2	ENST00000508989.5	c.1344G>C	p.Gln448His	missense_variant	9/33	2		ENSP00000425596.1
FBN2	ENST00000703787.1	n.1150G>C		non_coding_transcript_exon_variant	9/10

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461728 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727170

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: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Jun 25, 2019

Has not been previously published as pathogenic or benign to our knowledge; Not observed in large population cohorts (Lek et al., 2016); In silico analysis, which includes protein predictors and evolutionary conservation, supports that this variant does not alter protein structure/function; Does not affect a cysteine residue within a calcium-binding EGF-like domain of the FBN2 gene; cysteine substitutions in the calcium-binding EGF-like domains represent the majority of pathogenic missense changes associated with FBN2-related disorders (Collod-Beroud et al., 2003; Frederic et al., 2009). -

Congenital contractural arachnodactyly Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Nov 03, 2020

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) performed at Invitae indicates that this missense variant is not expected to disrupt FBN2 protein function. This variant has not been reported in the literature in individuals with FBN2-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces glutamine with histidine at codon 481 of the FBN2 protein (p.Gln481His). The glutamine residue is highly conserved and there is a small physicochemical difference between glutamine and histidine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.12
BayesDel_addAF	Benign	0.0030	T
BayesDel_noAF	Benign	-0.23
CADD	Benign	7.5
DANN	Benign	0.93
DEOGEN2	Benign	0.23	T;.;T;T
Eigen	Benign	-0.98
Eigen_PC	Benign	-0.85
FATHMM_MKL	Uncertain	0.83	D
LIST_S2	Benign	0.85	D;.;.;T
M_CAP	Benign	0.056	D
MetaRNN	Benign	0.18	T;T;T;T
MetaSVM	Benign	-0.86	T
MutationAssessor	Benign	0.90	L;.;L;.
PrimateAI	Uncertain	0.60	T
PROVEAN	Benign	-1.5	N;.;N;N
REVEL	Benign	0.27
Sift	Benign	0.036	D;.;D;T
Sift4G	Benign	0.15	.;.;.;T
Polyphen		0.12	B;.;B;B
Vest4		0.35
MutPred		0.65		Loss of disorder (P = 0.2076);.;Loss of disorder (P = 0.2076);.;
MVP		0.58
MPC		0.51
ClinPred		0.13	T
GERP RS		1.3
Varity_R		0.050
gMVP		0.40

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: rs923812426; hg19: chr5-127728850;