rs763759308
Variant summary
Our verdict is Uncertain significance. The variant received 3 ACMG points: 4P and 1B. PM1PP2PP3BP6
The NM_000138.5(FBN1):c.7559C>T(p.Thr2520Met) variant causes a missense change. The variant allele was found at a frequency of 0.000046 in 1,609,154 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). Synonymous variant affecting the same amino acid position (i.e. T2520T) has been classified as Likely benign.
Frequency
Consequence
NM_000138.5 missense
Scores
Clinical Significance
Conservation
Publications
- familial thoracic aortic aneurysm and aortic dissectionInheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: ClinGen, Orphanet
- Marfan syndromeInheritance: AD, AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp, ClinGen, G2P, PanelApp Australia, Orphanet, Ambry Genetics
- Acromicric dysplasiaInheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, Ambry Genetics
- progeroid and marfanoid aspect-lipodystrophy syndromeInheritance: AD Classification: STRONG, MODERATE, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, Orphanet
- stiff skin syndromeInheritance: AD Classification: STRONG, LIMITED Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
- Weill-Marchesani syndrome 2, dominantInheritance: AD Classification: STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae)
- geleophysic dysplasiaInheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
- isolated ectopia lentisInheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
- neonatal Marfan syndromeInheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
- Weill-Marchesani syndromeInheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
- ectopia lentis 1, isolated, autosomal dominantInheritance: AD Classification: LIMITED Submitted by: G2P
- Shprintzen-Goldberg syndromeInheritance: AD, Unknown Classification: LIMITED, NO_KNOWN Submitted by: ClinGen, Labcorp Genetics (formerly Invitae)
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ACMG classification
Our verdict: Uncertain_significance. The variant received 3 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.0000131 AC: 2AN: 152200Hom.: 0 Cov.: 33 show subpopulations
GnomAD2 exomes AF: 0.0000438 AC: 11AN: 251244 AF XY: 0.0000221 show subpopulations
GnomAD4 exome AF: 0.0000494 AC: 72AN: 1456954Hom.: 0 Cov.: 31 AF XY: 0.0000469 AC XY: 34AN XY: 725040 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.0000131 AC: 2AN: 152200Hom.: 0 Cov.: 33 AF XY: 0.0000135 AC XY: 1AN XY: 74338 show subpopulations
Age Distribution
ClinVar
Submissions by phenotype
Familial thoracic aortic aneurysm and aortic dissection Uncertain:1Benign:1
This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -
This missense variant replaces threonine with methionine at codon 2520 of the FBN1 protein. Computational prediction tool is inconclusive regarding the impact of this variant on protein structure and function. To our knowledge, functional studies have not been performed for this variant. This variant has been reported in individuals affected with Marfan syndrome (PMID: 17657824, 25053872, 34957211) and thoracic aortic aneurysm or dissection (PMID: 34150014, 34498425), as well as in an individual with Marfan syndrome-related cardiovascular phenotype (PMID: 31211626). It has been shown that this variant did not segregate with disease in several individuals across two families (PMID: 34498425, 34957211). This variant has been observed in an individual affected with ectopia lentis, who also carried a pathogenic truncation variant in the same gene (PMID: 28941062). This variant has also been identified in 12/282648 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. -
Marfan syndrome Uncertain:1
This missense variant replaces threonine with methionine at codon 2520 of the FBN1 protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). To our knowledge, functional studies have not been performed for this variant. This variant has been reported in individuals affected with Marfan syndrome (PMID: 17657824, 25053872, 34957211) and thoracic aortic aneurysm or dissection (PMID: 34150014, 34498425), as well as in an individual with Marfan syndrome-related cardiovascular phenotype (PMID: 31211626). The variant has been reported to lack segregation with phenotypes in two of the families (PMID: 34498425, 34957211). This variant has been observed in an individual with ectopia lentis, who also carried a pathogenic truncation variant in the same gene (PMID: 28941062). This variant has also been identified in 12/282648 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. -
Weill-Marchesani syndrome 2, dominant Uncertain:1
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Marfan syndrome;C4707243:Familial thoracic aortic aneurysm and aortic dissection Uncertain:1
This sequence change replaces threonine, which is neutral and polar, with methionine, which is neutral and non-polar, at codon 2520 of the FBN1 protein (p.Thr2520Met). This variant is present in population databases (rs763759308, gnomAD 0.03%). This missense change has been observed in individuals with clinical features of Marfan syndrome and/or clinical features of Marfan syndrome/FBN1-related conditions (PMID: 17657824, 25053872, 28941062, 31211626, 34150014, 37337769). ClinVar contains an entry for this variant (Variation ID: 495649). 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) indicates that this missense variant is expected to disrupt FBN1 protein function with a positive predictive value of 95%. 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. -
not specified Benign:1
Variant summary: FBN1 c.7559C>T (p.Thr2520Met) results in a non-conservative amino acid change located in the EGF-like calcium-binding domain (IPR001881) of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 4.4e-05 in 251404 control chromosomes. This frequency is not significantly higher than expected for a pathogenic variant in FBN1 causing Marfan Syndrome (4.4e-05 vs 0.00011), allowing no conclusion about variant significance. c.7559C>T has been reported in the literature in individuals with non-classical features Marfan Syndrome (Comeglio_2007, Vatti_2017, Li_2014). These report(s) do not provide unequivocal conclusions about association of the variant with Marfan Syndrome. Co-occurrences with an identical pathogenic variant in the FBN1 gene have been reported in the literature (Vatti_2017) and in our internal testing (FBN1 c.6940_6943dupTACA, p.Thr2315IlefsX4), providing supporting evidence for a benign role. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. One clinical diagnostic laboratory has submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation and classified the variant as uncertain significance. Based on the evidence outlined above, the variant was re-classified as likely benign. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at