rs144189837
Variant summary
Our verdict is Uncertain significance. Variant got 0 ACMG points: 4P and 4B. PM1PP2PP3BS2
The NM_000138.5(FBN1):āc.7379A>Gā(p.Lys2460Arg) variant causes a missense change. The variant allele was found at a frequency of 0.000106 in 1,614,072 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).
Frequency
Consequence
NM_000138.5 missense
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Uncertain_significance. Variant got 0 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.0000723 AC: 11AN: 152228Hom.: 0 Cov.: 33
GnomAD3 exomes AF: 0.0000637 AC: 16AN: 251300Hom.: 0 AF XY: 0.0000810 AC XY: 11AN XY: 135820
GnomAD4 exome AF: 0.000109 AC: 160AN: 1461844Hom.: 0 Cov.: 32 AF XY: 0.000100 AC XY: 73AN XY: 727226
GnomAD4 genome AF: 0.0000723 AC: 11AN: 152228Hom.: 0 Cov.: 33 AF XY: 0.0000941 AC XY: 7AN XY: 74378
ClinVar
Submissions by phenotype
not provided Uncertain:7
Has been reported in association with Marfan syndrome in published literature, and frequently referred to as a variant of uncertain significance (PMID: 17627385, 21895641, 24941995, 25644172, 29907982); Reported in cis with FBN1 p.(N542S) in a patient with bicuspid aortic valve, TAAD, and additional connective tissue features who also harbored variants in TGFBR3, NOTCH1, and LTBP1; the FBN1 variants segregated with systemic connective tissue features in his mother, and the TGFBR3 variant segregated with aortic root dilation in his father and siblings (PMID: 30255099); At the protein level, in silico analysis indicates that this missense variant does not alter protein structure/function; At the mRNA level, in silico analysis supports a deleterious effect on splicing; Does not affect a cysteine or calcium-binding residue within an EGF-like domain or a TGF-binding protein domain of the FBN1 gene; cysteine substitutions in the EGF-like domains represent the majority of pathogenic missense changes associated with FBN1-related disorders (PMID: 12938084); This variant is associated with the following publications: (PMID: 24055113, 25812041, 25637381, 24941995, 32123317, 25644172, 21895641, 29907982, 17627385, 34663891, 30255099, 12938084) -
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No ACMG evidence could be applied applied -
Marfan syndrome Uncertain:3
This missense variant replaces lysine with arginine at codon 2460 of the FBN1 protein. Computational prediction suggests that this variant may have deleterious impact on protein structure and function (internally defined REVEL score threshold >= 0.7, PMID: 27666373). Splice site prediction tools suggest that this variant may impact RNA splicing. However, an RNA study showed no abnormal splicing (PMID: 32123317). This variant has been reported in one individual affected with Marfan syndrome or Marfan-like phenotype (PMID: 17627385, 21895641) and in an individual affected with bicuspid aortic valve, a common congenital heart defect with increased prevalence of aortic dilatation/dissection (PMID: 30255099). This variant was also reported in an individual with aortic dissection and suspected hereditary thoracic aortic disease (PMID: 29907982) along with another individual who was affected with non-syndromic heritable thoracic aortic disorder (PMID: 25644172). This variant has also been identified in 20/282708 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -
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Familial thoracic aortic aneurysm and aortic dissection Uncertain:2
The p.K2460R variant (also known as c.7379A>G), located in coding exon 59 of the FBN1 gene, results from an A to G substitution at nucleotide position 7379. The lysine at codon 2460 is replaced by arginine, an amino acid with highly similar properties. This alteration has been reported in individuals from cohorts with Marfan syndrome or Marfan-like features; however, details were limited (Campens L et al. Orphanet J Rare Dis, 2015 Feb;10:9; Howarth R et al. Genet. Test., 2007;11:146-52). This variant was also detected in probands with bicuspid aortic valve, aortic dissection/dilation, and systemic features; however, other variants were also detected (Overwater E et al. Hum Mutat. 2018 09;39(9):1173-1192; Sticchi E et al. Biomed Res Int. 2018 Sep;2018:8386123). This alteration has also been seen in exome cohorts, but cardiovascular history was not provided (Dorschner MO et al. Am. J. Hum. Genet., 2013 Oct;93:631-40; Amendola LM et al. Genome Res., 2015 Mar;25:305-15). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -
This missense variant replaces lysine with arginine at codon 2460 of the FBN1 protein. Computational prediction suggests that this variant may have deleterious impact on protein structure and function (internally defined REVEL score threshold >= 0.7, PMID: 27666373). Splice site prediction tools suggest that this variant may impact RNA splicing. However, an RNA study showed no abnormal splicing (PMID: 32123317). This variant has been reported in one individual affected with Marfan syndrome or Marfan-like phenotype (PMID: 17627385, 21895641) and in an individual affected with bicuspid aortic valve, a common congenital heart defect with increased prevalence of aortic dilatation/dissection (PMID: 30255099). This variant was also reported in an individual with aortic dissection and suspected hereditary thoracic aortic disease (PMID: 29907982) along with another individual who was affected with non-syndromic heritable thoracic aortic disorder (PMID: 25644172). This variant has also been identified in 20/282708 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -
not specified Uncertain:1Benign:1
Variant identified in a genome or exome case(s) and assessed due to predicted null impact of the variant or pathogenic assertions in the literature or databases. Disclaimer: This variant has not undergone full assessment. The following are preliminary notes: Reported in 1 Marfan proband, 4/5 papers in HGMD classify as VUS due to presence in ESP. ClinVar: 2 VUS -
Variant summary: FBN1 c.7379A>G (p.Lys2460Arg) results in a conservative amino acid change in the encoded protein sequence. Three of five in-silico tools predict a damaging effect of the variant on protein function. Normal splicing of this variant was also reported (PMID 32123317). The variant allele was found at a frequency of 6.4e-05 in 251300 control chromosomes, predominantly at a frequency of 0.00013 within the Non-Finnish European subpopulation in the gnomAD database. The observed variant frequency within Non-Finnish European control individuals in the gnomAD database is approximately one fold of the estimated maximal expected allele frequency for a pathogenic variant in FBN1 causing Marfan Syndrome phenotype (0.00011). c.7379A>G has been reported in the literature in individuals affected with Marfan Syndrome and features of Marfan Syndrome, without strong evidence for causality (example, Howarth_2007, Robinson_2012, Overwater_2018). The variant was also not co-segregated with Bicuspid aortic valve, thoracic aortic root & ascending aorta dilatation in an Italian family (Sticchi_2018). These report(s) do not provide unequivocal conclusions about association of the variant with Marfan Syndrome. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 24055113, 17627385, 29907982, 21895641, 30255099, 24941995). ClinVar contains an entry for this variant (Variation ID: 161239). Based on the evidence outlined above, the variant was classified as likely benign. -
FBN1-related disorder Uncertain:1
The FBN1 c.7379A>G variant is predicted to result in the amino acid substitution p.Lys2460Arg. This variant was reported in multiple individuals with Marfan syndrome or related aortopathies (Howarth et al. 2007. PubMed ID: 17627385; Robinson et al. 2012. PubMed ID: 21895641; Campens et al. 2015. PubMed ID: 25644172; Growth et al. 2016. PubMed ID: 25812041). However, this variant was also found to co-occur with other rare variants in genes associated with Marfan syndrome phenotypes (Table S1, Overwater et al. 2018. PubMed ID: 29907982; Sticchi et al. 2018. PubMed ID: 30255099). This variant is reported in 0.015% of alleles in individuals of European (Non-Finnish) descent in gnomAD, which is more common than expected for disease-causing variant. At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -
Marfan syndrome;C4707243:Familial thoracic aortic aneurysm and aortic dissection Uncertain:1
This sequence change replaces lysine, which is basic and polar, with arginine, which is basic and polar, at codon 2460 of the FBN1 protein (p.Lys2460Arg). This variant is present in population databases (rs144189837, gnomAD 0.01%), and has an allele count higher than expected for a pathogenic variant. This missense change has been observed in individual(s) with clinical features of aortic aneurysm and/or clinical features of Marfan syndrome and thoracic aortic disorders (PMID: 17627385, 21895641, 25644172, 29907982, 30255099; internal data). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 161239). Invitae Evidence 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 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. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. 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:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at