FBN2

Chr 5AD

fibrillin 2

Also known as: CCA, DA9, EOMD

The protein is a component of connective tissue microfibrils and functions in elastic fiber assembly. Mutations cause congenital contractural arachnodactyly and early-onset macular degeneration through an autosomal dominant inheritance pattern. The gene is extremely intolerant to loss-of-function mutations, indicating that pathogenic variants likely act through dominant-negative or gain-of-function mechanisms rather than haploinsufficiency.

GeneReviewsOMIMResearchSummary from RefSeq, OMIM, UniProt
DNmechanismADLOEUF 0.202 OMIM phenotypes
Clinical SummaryFBN2
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Gene-Disease Validity (ClinGen)
congenital contractural arachnodactyly · ADDefinitive

Definitive — sufficient evidence for diagnostic panels

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.
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Clinical Trials
1 active or recruiting trial — potential therapeutic options may be available
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GeneReview available — FBN2
Authoritative clinical overview · Recommended first read
Open GeneReview ↗

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

LoF intolerant — likely haploinsufficient
LoF Constraint
0.20LOEUF
pLI 1.000
Z-score 9.83
OE 0.14 (0.100.20)
Highly constrained

Highly LoF-intolerant (top ~10% of genes)

Missense Constraint
1.55Z-score
OE missense 0.89 (0.850.93)
1456 obs / 1632.1 exp
Tolerant

Mild missense constraint

Observed / Expected Ratios
LoF OE0.14 (0.100.20)
00.351.4
Missense OE0.89 (0.850.93)
00.61.4
Synonymous OE1.06
01.21.6
LoF obs/exp: 22 / 153.4Missense obs/exp: 1456 / 1632.1Syn Z: -1.07
Curated Mechanism (G2P)Gene2Phenotype (DDG2P) ↗
definitiveFBN2-related congenital contractural arachnodactylyDNAD
DN
0.4487th %ile
GOF
0.5171th %ile
LOF
0.61top 25%

The highest-scoring mechanism for this gene is loss-of-function (haploinsufficiency).

LOF1 literature citation · LOEUF 0.20

Note: In-silico variant effect predictors (SIFT, PolyPhen, REVEL, CADD) may underestimate pathogenicity of missense variants in genes with GOF or DN mechanisms. Consider functional evidence and clinical context.

Literature Evidence

LOFHaploinsufficiency for FBN2 accounts for the digital and auricular features.PMID:25195018

Predictions from Badonyi M, Marsh JA. PLoS ONE. 2024;19(8):e0307312. Mechanism ranking also informed by gnomAD constraint, ClinVar, and ClinGen data.

ClinVar Variant Classifications

0 submitted variants in ClinVar

Protein Context — Lollipop Plot

FBN2 · protein map & ClinVar variants

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

3D Protein StructureAlphaFold
Clinical Literature
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