FBN1

Chr 15AD

fibrillin 1

Structural component of the 10-12 nm diameter microfibrils of the extracellular matrix, which conveys both structural and regulatory properties to load-bearing connective tissues (PubMed:15062093, PubMed:1860873). Fibrillin-1-containing microfibrils provide long-term force bearing structural support (PubMed:27026396). In tissues such as the lung, blood vessels and skin, microfibrils form the periphery of the elastic fiber, acting as a scaffold for the deposition of elastin (PubMed:27026396). In addition, microfibrils can occur as elastin-independent networks in tissues such as the ciliary zonule, tendon, cornea and glomerulus where they provide tensile strength and have anchoring roles (PubMed:27026396). Fibrillin-1 also plays a key role in tissue homeostasis through specific interactions with growth factors, such as the bone morphogenetic proteins (BMPs), growth and differentiation factors (GDFs) and latent transforming growth factor-beta-binding proteins (LTBPs), cell-surface integrins and other extracellular matrix protein and proteoglycan components (PubMed:27026396). Regulates osteoblast maturation by controlling TGF-beta bioavailability and calibrating TGF-beta and BMP levels, respectively (By similarity). Negatively regulates osteoclastogenesis by binding and sequestering an osteoclast differentiation and activation factor TNFSF11 (PubMed:24039232). This leads to disruption of TNFSF11-induced Ca(2+) signaling and impairment of TNFSF11-mediated nuclear translocation and activation of transcription factor NFATC1 which regulates genes important for osteoclast differentiation and function (PubMed:24039232). Mediates cell adhesion via its binding to cell surface receptors integrins ITGAV:ITGB3 and ITGA5:ITGB1 (PubMed:12807887, PubMed:17158881). Binds heparin and this interaction has an important role in the assembly of microfibrils (PubMed:11461921)

Primary Disease Associations & Inheritance

Acromicric dysplasiaMIM #102370
AD
Ectopia lentis, familialMIM #129600
AD
Geleophysic dysplasia 2MIM #614185
AD
Marfan lipodystrophy syndromeMIM #616914
AD
Marfan syndromeMIM #154700
AD
MASS syndromeMIM #604308
AD
Stiff skin syndromeMIM #184900
AD
Weill-Marchesani syndrome 2, dominantMIM #608328
AD
UniProtEctopia lentis 1, isolated, autosomal dominant
UniProtOverlap connective tissue disease
UniProtMarfanoid-progeroid-lipodystrophy syndrome
0
ClinVar variants
0
Pathogenic / LP
1.00
pLI score· haploinsufficient
8
Active trials
Clinical SummaryFBN1
Population Constraint (gnomAD)
Highly constrained gene — heterozygous loss-of-function variants are very rare in the population (pLI 1.00). One damaged copy is likely sufficient to cause disease.
💊
Clinical Trials
8 active or recruiting trials — potential therapeutic options may be available
Some data sources returned errors (2)

ncbi: Error: NCBI fetch failed: 429 https://eutils.ncbi.nlm.nih.gov/entrez/eutils/esearch.fcgi

clinvarCount: Error: NCBI fetch failed: 429 https://eutils.ncbi.nlm.nih.gov/entrez/eutils/esearch.fcgi

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

Dual constrained — LoF & missense intolerant
LoF Constraint?LOEUF (Loss-of-function Observed/Expected Upper bound Fraction) is the upper bound of the 90% CI for LoF OE — the preferred gnomAD v4 metric. Lower = more intolerant to LoF. LOEUF < 0.35 = highly constrained.
0.05LOEUF
pLI 1.000
Z-score 11.46
OE 0.02 (0.010.05)
Highly constrained

Among the most LoF-intolerant genes (~top 3%)

Missense Constraint?Missense Z-score: standard deviations fewer missense variants observed vs. expected. Z > 3.09 (p < 0.001) = gene does not tolerate missense variation. OE missense < 0.6 is also considered constrained.
5.06Z-score
OE missense 0.64 (0.610.68)
1038 obs / 1609.8 exp
Constrained

Extremely missense-constrained (top ~0.01%)

Observed / Expected Ratios?Shaded band = 90% confidence interval. Vertical tick = point estimate. Grey threshold line = gnomAD constraint cutoff for that variant class.
LoF OE?Ratio of observed to expected LoF variants. Upper CI bound (LOEUF) ≤ 0.35 = strong LoF constraint signal.0.02 (0.010.05)
00.351.4
Missense OE?Ratio of observed to expected missense variants. OE ≤ 0.6 = fewer missense variants than expected by chance.0.64 (0.610.68)
00.61.4
Synonymous OE?Control metric — synonymous variants are largely neutral and expected near OE = 1.0. Significant deviation may indicate annotation issues.0.99
01.21.6
LoF obs/exp: 3 / 158.8Missense obs/exp: 1038 / 1609.8Syn Z: 0.22

ClinVar Variant Classifications

0 submitted variants in ClinVar

Protein Context — Lollipop Plot

FBN1 · protein map & ClinVar variants

Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.

Gene2Phenotype Curations

FBN1-related isolated ectopia lentis

limited
ADUndeterminedAltered Gene Product Structure
EyeSkin
G2P ↗
missense variantinframe deletioninframe insertion

FBN1-related Weill-Marchesani syndrome

strong
ADUndeterminedAltered Gene Product Structure
Dev. DisordersEyeSkinSkeletal
G2P ↗
missense variantinframe deletioninframe insertion

FBN1-related Marfan syndrome (biallelic)

definitive
ARLoss Of FunctionAbsent Gene Product, Altered Gene Product Structure
Dev. DisordersEyeSkinSkeletal
G2P ↗
splice region variantframeshift variantmissense variant

FBN1-related Marfan syndrome (monoallelic)

definitive
ADLoss Of FunctionAbsent Gene Product, Altered Gene Product Structure
Dev. DisordersEyeSkinSkeletal
G2P ↗

Gene2Phenotype curations · DECIPHER consortium patient cohort (public variants) · deciphergenomics.org

OMIM — Genotype-Phenotype Relationships

1 OMIM entry

FIBRILLIN 1; FBN1
MIM #134797 · *

Acromicric dysplasia

MIM #102370

Molecular basis of disorder known

Autosomal dominant

Ectopia lentis, familial

MIM #129600

Molecular basis of disorder known

Autosomal dominant

Geleophysic dysplasia 2

MIM #614185

Molecular basis of disorder known

Autosomal dominant

Marfan lipodystrophy syndrome

MIM #616914

Molecular basis of disorder known

Autosomal dominant

Marfan syndrome

MIM #154700

Molecular basis of disorder known

Autosomal dominant

MASS syndrome

MIM #604308

Molecular basis of disorder known

Autosomal dominant

Stiff skin syndrome

MIM #184900

Molecular basis of disorder known

Autosomal dominant

Weill-Marchesani syndrome 2, dominant

MIM #608328

Molecular basis of disorder known

Autosomal dominant

Clinical Trials

Active and recruiting trials from ClinicalTrials.gov

Cardiomyopathy, HypertrophicCardiomyopathy, DilatedCardiomyopathy Restrictive

National Network for Cardiovascular Genomics: Advancing Cardiovascular Healthcare for Hereditary Diseases in Brazil's Unified Health System Through a Multicenter Registry

RECRUITING
NCT06546137Hospital do CoracaoStarted 2025-04-30
whole genome sequencing
Rare DiseasesThoracic Aortic Aneurysm (TAA)Marfan Syndrome

Fibroblasts and Thoracic Aortic Aneurysms: in Vitro Characterization in With Marfan Syndrome and Genetic Aortic Diseases

ENROLLING BY INVITATION
NCT06786754IRCCS Policlinico S. DonatoStarted 2025-06-17
AortopathiesThoracic Aortic AneurysmAortic Valve Disease

Pathogenetic Basis of Aortopathy and Aortic Valve Disease

ACTIVE NOT RECRUITING
NCT03440697Yale UniversityStarted 2015-12-10
Marfan SyndromeMarfan's Syndrome With Cardiovascular Manifestations

Transcriptomic Study of Adult Population With Marfan Syndrome

RECRUITING
NCT05700175IRCCS Policlinico S. DonatoStarted 2021-11-02
Transcriptomic, epigenetic and proteomic analysis
Lipodystrophy (Genetic or Acquired, Non HIV)

The LD Lync Study - Natural History Study of Lipodystrophy Syndromes

RECRUITING
NCT03087253University of MichiganStarted 2018-02-27
Obstetric PainCesarean SectionPostoperative Pain

The Relationship Between Preoperative Serum Asprosin Level and Postoperative Analgesic Consumption in Patients Undergoing Caesarean Section

NOT YET RECRUITING
NCT06304246Firat UniversityStarted 2024-03-01
Measurement Pain ThresholdMeasurement of Serum Asprosin
Acute Aortic DissectionThoracic Aortic Aneurysm

Genetic Architecture of Acute Aortic Syndromes and Aortic Aneurysm.

RECRUITING
NCT06353607University Hospital, Basel, SwitzerlandStarted 2024-04-08
Creation of an Italian Network of Biobanks of Rare Diseases

ScATtEred Rare Disease Biobanks: a Model of Sample/Data Collection With susTainablE and Shared Criteria

RECRUITING
NCT06782230IRCCS Policlinico S. DonatoStarted 2024-08-31