NM_000138.5:c.4937G>A

Variant names:

• chr15-48465573-C-T
• rs397515814
• NM_000138.5:c.4937G>A

Variant summary

Our verdict is Pathogenic. The variant received 19 ACMG points: 19P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_000138.5(FBN1):​c.4937G>A​(p.Cys1646Tyr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. C1646S) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 7.91
• 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 19 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 13 uncertain in NM_000138.5
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr15-48465574-A-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 1163970.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP2: Missense variant in the FBN1 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 1311 curated pathogenic missense variants (we use a threshold of 10). The gene has 112 curated benign missense variants. Gene score misZ: 5.0644 (above the threshold of 3.09). Trascript score misZ: 8.1787 (above the threshold of 3.09). GenCC associations: The gene is linked to Marfan syndrome, Weill-Marchesani syndrome 2, dominant, progeroid and marfanoid aspect-lipodystrophy syndrome, geleophysic dysplasia, Shprintzen-Goldberg syndrome, stiff skin syndrome, familial thoracic aortic aneurysm and aortic dissection, isolated ectopia lentis, ectopia lentis 1, isolated, autosomal dominant, Acromicric dysplasia, neonatal Marfan syndrome, Weill-Marchesani syndrome.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.991
• PP5: Variant 15-48465573-C-T is Pathogenic according to our data. Variant chr15-48465573-C-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 42372.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.4937G>A	p.Cys1646Tyr	missense_variant	Exon 40 of 66	ENST00000316623.10	NP_000129.3
FBN1	NM_001406716.1	c.4937G>A	p.Cys1646Tyr	missense_variant	Exon 39 of 65		NP_001393645.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
FBN1	ENST00000316623.10	c.4937G>A	p.Cys1646Tyr	missense_variant	Exon 40 of 66	1	NM_000138.5	ENSP00000325527.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Marfan syndrome Pathogenic:1

Mar 01, 2008

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Pathogenic:1

Dec 01, 2017

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The C1646Y pathogenic variant in the FBN1 gene has been reported in an adolescent male who fulfilled Ghent criteria for Marfan syndrome (Lerner-Ellis et al., 2014). Moreover, C1646Y appeared to be de novo in this affected male upon negative testing of both parents, although non-paternity was not ruled out (Lerner-Ellis et al., 2014). The C1646Y variant is a non-conservative amino acid substitution, which is likely to impact secondary protein structure as these residues differ in polarity, charge, size and/or other properties. In-silico analyses, including protein predictors and evolutionary conservation, support a deleterious effect. Furthermore, the C1646Y variant affects a Cysteine residue within a calcium-binding EGF-like domain of the FBN1 gene, which may affect disulfide bonding and is predicted to alter the structure and function of the protein. Cysteine substitutions in the calcium-binding EGF-like domains represent the majority of pathogenic missense changes associated with Marfan syndrome (Collod-Beroud et al., 2003). Finally, the C1646Y variant is not observed in large population cohorts (Lek et al., 2016), -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.60
CADD	Pathogenic	33
DANN	Uncertain	1.0
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Pathogenic	0.98	D
M_CAP	Pathogenic	0.96	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	0.97	D
PhyloP100		7.9
PrimateAI	Pathogenic	0.92	D
PROVEAN	Pathogenic	-9.5	D
REVEL	Pathogenic	0.94
Sift	Pathogenic	0.0	D
Sift4G	Uncertain	0.016	D
Vest4		0.97
MutPred		0.85		Gain of phosphorylation at C1646 (P = 0.0207);
MVP		0.99
MPC		1.9
ClinPred		1.0	D
GERP RS		6.2
Mutation Taster		=0/100	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.29		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.29		Position offset: 3

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

Other links and lift over

dbSNP: rs397515814; hg19: chr15-48757770;