ClinVar Genomic variation as it relates to human health

NM_000138.5 c.2956G>A is a missense variant in FBN1 predicted to cause a substitution of an alanine by a threonine at amino acid 986 (p.Ala986Thr). This variant has been identified in numerous individuals with diagnoses or suspicion of Marfan syndrome in both the published literature and internal databases (PP4; PMIDs: 24793577, 26410935, 27582083, 28679693, 28387797; Bichat, Mayo, UZG, UZA); however, in at least 3 of these cases, another pathogenic variant in FBN1 was also present (BP2; Bichat). This variant has been previously reported in ClinVar as likely benign or benign by more than 20 laboratories (Variation ID: 36060). It is present in gnomAD v2.1.1 at a frequency of 0.19% (245/129170 alleles) in the European sub-population (BA1; https://gnomad.broadinstitute.org/). Computational prediction tools and conservation analysis are unclear about a predicted impact of this variant. In summary, this variant meets criteria to be classified as benign for Marfan syndrome based on the ACMG/AMP criteria applied, as specified by the ClinGen FBN1 VCEP: BA1, BP2, PP4. The pathogenic evidence code PP4 was not considered to be in conflict with this conclusion.

p.Ala986Thr in exon 25 of FBN1: This variant is not expected to have clinical si gnificance because it has been identified in 0.198% (134/67678) of non-Finnish E uropean chromosomes by the Exome Aggregation Consortium (ExAC, http://exac.broad institute.org; dbSNP rs112287730). This variant has been reported in 5 individua ls with clinical features of Marfan syndrom and/or connective tissue disorder, b ut was also identified in 2 unaffected relatives from two families (Rommel 2002, Frederic 2009, Aboni 2013, Lerner-Ellis 2014).

This variant is associated with the following publications: (PMID: 16220557, 24793577, 12402346, 19370756, 27582083, 26410935, 28387797, 23608731, 28679693)

FBN1 NM_000138.4 exon 25 p.Ala986Thr (c.2956G>A): This variant has been reported in the literature in at least 4 individuals with features of connective tissues disorders (Lerner-Ellis 2014 PMID:24793577, Arnaud 2017 PMID:27582083, Cousin 2017 PMID:28679693, Girdauskas 2017 PMID:28387797). However, this variant is also present in 0.1% (20/10474) of Finnish alleles in the Genome Aggregation Database (https://gnomad.broadinstitute.org/variant/15-48489977-C-T?dataset=gnomad_r3) and is present in ClinVar, with several labs classifying this variant as benign or likely benign (Variation ID:36060). Evolutionary conservation and computational predictive tools suggest that this variant may not impact the protein. In summary, data on this variant suggests that this variant does not cause disease, but requires further evidence. Therefore this variant is classified as likely benign.

This alteration is classified as 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.

FBN1: BS1

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign.

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign.

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign.

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign.

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign.

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases did not allow this variant to be ruled in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance.

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign.

This variant is classified as likely benign based on ACMG/AMP sequence variant interpretation guidelines (Richards et al. 2015 PMID: 25741868, with internal and published modifications).