rs1555405028

Variant names:

• chr15-48600139-GT-G
• rs1555405028
• NM_000138.5:c.441delA

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000138.5(FBN1):​c.441delA​(p.Gln147HisfsTer43) variant causes a frameshift, splice region change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 1/1 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 33)
• Consequence: FBN1 NM_000138.5 frameshift, splice_region
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 0.213
• Publications: 0 publications found

Genes affected

FBN1 (HGNC:3603): (fibrillin 1) This gene encodes a member of the fibrillin family of proteins. The encoded preproprotein is proteolytically processed to generate two proteins including the extracellular matrix component fibrillin-1 and the protein hormone asprosin. Fibrillin-1 is an extracellular matrix glycoprotein that serves as a structural component of calcium-binding microfibrils. These microfibrils provide force-bearing structural support in elastic and nonelastic connective tissue throughout the body. Asprosin, secreted by white adipose tissue, has been shown to regulate glucose homeostasis. Mutations in this gene are associated with Marfan syndrome and the related MASS phenotype, as well as ectopia lentis syndrome, Weill-Marchesani syndrome, Shprintzen-Goldberg syndrome and neonatal progeroid syndrome. [provided by RefSeq, Apr 2016]

FBN1 Gene-Disease associations (from GenCC):

• familial thoracic aortic aneurysm and aortic dissection

  Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: ClinGen, Orphanet
• Marfan syndrome

  Inheritance: AD, AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp, ClinGen, G2P, PanelApp Australia, Orphanet, Ambry Genetics
• Acromicric dysplasia

  Inheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, Ambry Genetics
• progeroid and marfanoid aspect-lipodystrophy syndrome

  Inheritance: AD Classification: STRONG, MODERATE, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, Orphanet
• stiff skin syndrome

  Inheritance: AD Classification: STRONG, LIMITED Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
• Weill-Marchesani syndrome 2, dominant

  Inheritance: AD Classification: STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae)
• geleophysic dysplasia

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• isolated ectopia lentis

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• neonatal Marfan syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Weill-Marchesani syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• ectopia lentis 1, isolated, autosomal dominant

  Inheritance: AD Classification: LIMITED Submitted by: G2P
• Shprintzen-Goldberg syndrome

  Inheritance: AD, Unknown Classification: LIMITED, NO_KNOWN Submitted by: ClinGen, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Pathogenic. The variant received 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 15-48600139-GT-G is Pathogenic according to our data. Variant chr15-48600139-GT-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 527202.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
FBN1	NM_000138.5	c.441delA	p.Gln147HisfsTer43	frameshift_variant, splice_region_variant	Exon 5 of 66	ENST00000316623.10	NP_000129.3
FBN1	NM_001406716.1	c.441delA	p.Gln147HisfsTer43	frameshift_variant, splice_region_variant	Exon 4 of 65		NP_001393645.1
FBN1	NM_001406717.1	c.441delA	p.Gln147HisfsTer43	frameshift_variant, splice_region_variant	Exon 5 of 9		NP_001393646.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
FBN1	ENST00000316623.10	c.441delA	p.Gln147HisfsTer43	frameshift_variant, splice_region_variant	Exon 5 of 66	1	NM_000138.5	ENSP00000325527.5
FBN1	ENST00000559133.6	n.441delA		splice_region_variant, non_coding_transcript_exon_variant	Exon 5 of 67	1		ENSP00000453958.2
FBN1	ENST00000537463.6	n.441delA		splice_region_variant, non_coding_transcript_exon_variant	Exon 5 of 31	5		ENSP00000440294.2
FBN1	ENST00000674301.2	n.441delA		splice_region_variant, non_coding_transcript_exon_variant	Exon 5 of 68			ENSP00000501333.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Marfan Syndrome/Loeys-Dietz Syndrome/Familial Thoracic Aortic Aneurysms and Dissections Pathogenic:1

Nov 05, 2018

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: FBN1 c.441delA (p.Gln147HisfsX43) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Truncations downstream of this position have been classified as pathogenic by our laboratory (eg. c.493C>T, p.Arg165X; c.643C>T, p.Arg215X; c.1010dupA, p.Tyr337X). The variant was absent in 245954 control chromosomes (gnomAD). The variant, c.441delA, has been reported in the literature in one individual affected with Marfan Syndrome (Vatti_2017). This report does 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. 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 pathogenic. Based on the evidence outlined above, the variant was classified as likely pathogenic -

Marfan syndrome;C4707243:Familial thoracic aortic aneurysm and aortic dissection Pathogenic:1

Aug 23, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 527202). This variant is also known as c.441delA, p.Gln147*. This premature translational stop signal has been observed in individual(s) with clinical features of Marfan syndrome (PMID: 28941062). This variant is not present in population databases (gnomAD no frequency). This sequence change creates a premature translational stop signal (p.Gln147Hisfs*43) in the FBN1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in FBN1 are known to be pathogenic (PMID: 17657824, 19293843). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		0.21
Mutation Taster		=0/200	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.070		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs1555405028; hg19: chr15-48892336;