15-48474293-CACAG-C

Variant names:

• chr15-48474293-CACAG-C
• rs1555397655
• NM_000138.5:c.4168_4171delCTGT

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.4168_4171delCTGT​(p.Leu1390AlafsTer22) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. L1390L) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 32)
• Consequence: FBN1 NM_000138.5 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 9.05
• Publications: 1 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 15-48474293-CACAG-C is Pathogenic according to our data. Variant chr15-48474293-CACAG-C is described in ClinVar as Pathogenic. ClinVar VariationId is 517371.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000138.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	FBN1	NM_000138.5	MANE Select	c.4168_4171delCTGT	p.Leu1390AlafsTer22	frameshift	Exon 34 of 66	NP_000129.3
	FBN1	NM_001406716.1		c.4168_4171delCTGT	p.Leu1390AlafsTer22	frameshift	Exon 33 of 65	NP_001393645.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	FBN1	ENST00000316623.10	TSL:1 MANE Select	c.4168_4171delCTGT	p.Leu1390AlafsTer22	frameshift	Exon 34 of 66	ENSP00000325527.5
	FBN1	ENST00000559133.6	TSL:1	n.4168_4171delCTGT		non_coding_transcript_exon	Exon 34 of 67	ENSP00000453958.2
	FBN1	ENST00000537463.6	TSL:5	n.840_843delCTGT		non_coding_transcript_exon	Exon 9 of 31	ENSP00000440294.2

Frequencies

GnomAD3 genomes Cov.: 32

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Marfan syndrome Pathogenic:2

Mar 01, 2021

Centre of Medical Genetics, University of Antwerp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: research

PM2, PVS1, PP4

Jul 27, 2017

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.Leu1390fs variant in FBN1 has been reported in one Chinese individual with clinical features of Marfan syndrome, segregated with disease in one affected r elative (Wang 2013) and was absent from large population studies, though the abi lity of these studies to accurately detect indels may be limited. This variant i s predicted to cause a frameshift, which alters the protein?s amino acid sequenc e beginning at position 1930 and leads to a premature termination codon 22 amino acids downstream. This alteration is then predicted to lead to a truncated or a bsent protein. Heterozygous loss of function of the FBN1 gene is an established disease mechanism in Marfan syndrome. In summary, this variant meets criteria to be classified as pathogenic for Marfan syndrome in an autosomal dominant manner based upon the predicted impact to the protein and absence in controls.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		9.0
Mutation Taster		=0/200	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		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: rs1555397655; hg19: chr15-48766490;