rs202219940

Positions:

• chr5-128344387-G-A

Variant summary

Our verdict is Likely benign. Variant got -3 ACMG points: 2P and 5B. PP2 PP3 BS1_Supporting BS2

The NM_001999.4(FBN2):​c.3341C>T​(p.Thr1114Met) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000861 in 1,613,818 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: 𝑓 0.00013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000081 (0 hom.)
• Consequence: FBN2 NM_001999.4 missense, splice_region
• Scores: Splicing: ADA: 0.9991
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:4
• Conservation: PhyloP100: 9.88

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_benign. Variant got -3 ACMG points.

• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), FBN2. . Gene score misZ 1.5491 (greater than the threshold 3.09). Trascript score misZ 3.2752 (greater than threshold 3.09). GenCC has associacion of gene with familial thoracic aortic aneurysm and aortic dissection, carpal tunnel syndrome, macular degeneration, early-onset, congenital contractural arachnodactyly.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.801
• BS1: Variant frequency is greater than expected in population amr. gnomad4_exome allele frequency = 0.0000814 (119/1461656) while in subpopulation AMR AF= 0.000402 (18/44724). AF 95% confidence interval is 0.000259. There are 0 homozygotes in gnomad4_exome. There are 64 alleles in male gnomad4_exome subpopulation. Median coverage is 31. This position pass quality control queck. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting
• BS2: High AC in GnomAd4 at 20 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
FBN2	NM_001999.4	c.3341C>T	p.Thr1114Met	missense_variant, splice_region_variant	25/65	ENST00000262464.9	NP_001990.2
FBN2	XM_017009228.3	c.3188C>T	p.Thr1063Met	missense_variant, splice_region_variant	24/64		XP_016864717.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
FBN2	ENST00000262464.9	c.3341C>T	p.Thr1114Met	missense_variant, splice_region_variant	25/65	1	NM_001999.4	ENSP00000262464.4
FBN2	ENST00000508989.5	c.3242C>T	p.Thr1081Met	missense_variant, splice_region_variant	24/33	2		ENSP00000425596.1

Frequencies

GnomAD3 genomes AF: 0.000131 AC: 20 AN: 152162 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.000121

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00144

Gnomad EAS AF: 0.000192

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000132

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.000127 AC: 32 AN: 251384 Hom.: 0 AF XY: 0.000147 AC XY: 20 AN XY: 135856

Gnomad AFR exome AF: 0.0000615

Gnomad AMR exome AF: 0.000463

Gnomad ASJ exome AF: 0.000198

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.000163

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000528

Gnomad OTH exome AF: 0.000326

GnomAD4 exome AF: 0.0000814 AC: 119 AN: 1461656 Hom.: 0 Cov.: 31 AF XY: 0.0000880 AC XY: 64 AN XY: 727146

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.000402

Gnomad4 ASJ exome AF: 0.000651

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.000185

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000594

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome AF: 0.000131 AC: 20 AN: 152162 Hom.: 0 Cov.: 32 AF XY: 0.000108 AC XY: 8 AN XY: 74332

Gnomad4 AFR AF: 0.000121

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00144

Gnomad4 EAS AF: 0.000192

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000132

Gnomad4 OTH AF: 0.00

Alfa AF: 0.000164 Hom.: 0

Bravo AF: 0.000136

ExAC AF: 0.000115 AC: 14

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:2

Uncertain significance, criteria provided, single submitter	not provided	Breakthrough Genomics, Breakthrough Genomics	-	- -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	May 09, 2024	Has not been previously published as pathogenic or benign to our knowledge; In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Although located in a calcium-binding EGF-like domain of the FBN2 gene, it does not substitute or introduce a cysteine residue (PMID: 18767143, 19006240); This variant is associated with the following publications: (PMID: 18767143, 19006240) -

Congenital contractural arachnodactyly Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 13, 2018	This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -
Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Aug 16, 2023	This sequence change replaces threonine, which is neutral and polar, with methionine, which is neutral and non-polar, at codon 1114 of the FBN2 protein (p.Thr1114Met). This variant is present in population databases (rs202219940, gnomAD 0.05%), and has an allele count higher than expected for a pathogenic variant. This variant has not been reported in the literature in individuals affected with FBN2-related conditions. ClinVar contains an entry for this variant (Variation ID: 213306). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.25
BayesDel_addAF	Uncertain	0.065	T
BayesDel_noAF	Pathogenic	0.20
CADD	Pathogenic	34
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.76	D;.;D;D
Eigen	Pathogenic	0.70
Eigen_PC	Uncertain	0.65
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Benign	0.80	T;.;.;T
M_CAP	Uncertain	0.096	D
MetaRNN	Pathogenic	0.80	D;D;D;D
MetaSVM	Uncertain	0.52	D
MutationAssessor	Uncertain	2.3	M;.;M;.
PrimateAI	Uncertain	0.74	T
PROVEAN	Uncertain	-4.3	D;.;D;D
REVEL	Pathogenic	0.72
Sift	Uncertain	0.0030	D;.;D;D
Sift4G	Uncertain	0.051	.;.;.;T
Polyphen		1.0	D;.;D;D
Vest4		0.87
MVP		0.82
MPC		0.87
ClinPred		0.65	D
GERP RS		4.3
Varity_R		0.35
gMVP		0.64

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.78
SpliceAI score (max)		0.010		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: rs202219940; hg19: chr5-127680079; COSMIC: COSV52497338;