5-128338114-C-T

Variant names:

• chr5-128338114-C-T
• rs1554123065
• NM_001999.4:c.3481G>A

Variant summary

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

The NM_001999.4(FBN2):​c.3481G>A​(p.Glu1161Lys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: FBN2 NM_001999.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:4
• Conservation: PhyloP100: 7.91

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 Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.992

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
FBN2	NM_001999.4	c.3481G>A	p.Glu1161Lys	missense_variant	Exon 27 of 65	ENST00000262464.9	NP_001990.2
FBN2	XM_017009228.3	c.3328G>A	p.Glu1110Lys	missense_variant	Exon 26 of 64		XP_016864717.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
FBN2	ENST00000262464.9	c.3481G>A	p.Glu1161Lys	missense_variant	Exon 27 of 65	1	NM_001999.4	ENSP00000262464.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1461668 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727118

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:4

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:2

Nov 10, 2022

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Identified in a patient with tall stature, arachnodactyly, camptodactyly, scoliosis, pectus deformity, myopia, and beaked nose but it is unknown whether this individual was screened for variants in other genes associated with this phenotype (Callewaert et al., 2009); Identified in an individual with pes planus, pectus abnormality, facial features, elbow hyperextensibility, high myopia, mild aortic dilatation, severe lumbar scoliosis, wrist and thumb sign, high-arched palate, and marfanoid habitus who also harbored a variant in the FBN1 gene (Najafi et al., 2020); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; In silico analysis is inconclusive as to whether the variant alters gene splicing. In the absence of RNA/functional studies, the actual effect of this sequence change is unknown.; Although located in a calcium-binding EGF-like domain of the FBN2 gene, it does not substitute or introduce a cysteine residue (Callewaert et al., 2009; Frederic et al., 2009); Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 19006240, 18767143, 31506931) -

Nov 01, 2019

CeGaT Center for Human Genetics Tuebingen

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Congenital contractural arachnodactyly;C4015286:Macular degeneration, early-onset Uncertain:2

Oct 31, 2018

Fulgent Genetics, Fulgent Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Mar 30, 2021

Center for Genomics, Ann and Robert H. Lurie Children's Hospital of Chicago

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

FBN2 NM_001999.3 exon27 p.Glu1161Lys (c.3481G>A): This variant has been reported in the literature in 1 individual with congenital contractural arachnodactyly, segregating with disease in 4 affected family members (Callewaert 2009 PMID:19006240). Additionally, this variant is not present in large control databases. This variant is present in ClinVar (Variation ID: 458759). Evolutionary consevation and computational predictive tools suggest that this variant may impact the protein. In summary, data on this variant is insufficient for disease classification. Therefore, the clinical significance of this variant is uncertain. -

Congenital contractural arachnodactyly Pathogenic:1

Oct 24, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glutamic acid, which is acidic and polar, with lysine, which is basic and polar, at codon 1161 of the FBN2 protein (p.Glu1161Lys). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with autosomal dominant congenital contractural arachnodactyly (PMID: 19006240, 31506931). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 458759). 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 expected to disrupt FBN2 protein function. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.94
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.58
CADD	Pathogenic	28
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.89	D;.;D;D;D
Eigen	Pathogenic	0.99
Eigen_PC	Pathogenic	0.90
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D;.;.;D;D
M_CAP	Pathogenic	0.74	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.3	M;.;M;.;.
PrimateAI	Pathogenic	0.90	D
PROVEAN	Uncertain	-3.7	D;.;D;D;D
REVEL	Pathogenic	0.97
Sift	Pathogenic	0.0	D;.;D;D;D
Sift4G	Pathogenic	0.0	.;.;.;D;D
Polyphen		1.0	D;.;D;.;D
Vest4		0.95
MutPred		0.96		Gain of methylation at E1161 (P = 0.0017);.;Gain of methylation at E1161 (P = 0.0017);.;.;
MVP		0.96
MPC		0.91
ClinPred		1.0	D
GERP RS		4.9
Varity_R		0.96
gMVP		0.96

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.28		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.28		Position offset: 8

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

Publications

LitVar

Other links and lift over

dbSNP: rs1554123065; hg19: chr5-127673806; COSMIC: COSV52493156;