FBXL20

Chr 17

F-box and leucine rich repeat protein 20

Also known as: Fbl2, Fbl20

NCBI Gene: 84961 ENSG00000108306 UniProt: Q96IG2

Members of the F-box protein family, such as FBXL20, are characterized by an approximately 40-amino acid F-box motif. SCF complexes, formed by SKP1 (MIM 601434), cullin (see CUL1; MIM 603134), and F-box proteins, act as protein-ubiquitin ligases. F-box proteins interact with SKP1 through the F box, and they interact with ubiquitination targets through other protein interaction domains (Jin et al., 2004 [PubMed 15520277]).[supplied by OMIM, Mar 2008]

Active trials

Pathogenic / LP

ClinVar variants

Pubs (1 yr)

3.1

Missense Z· constrained

0.26

LOEUF· LoF intolerant

Clinical Summary— FBXL20

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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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ClinVar Variants

8 Pathogenic / Likely Pathogenic· 33 VUS of 43 total submissions

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Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

gnomAD

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.

0.26LOEUF

pLI 0.997

Z-score 4.59

OE 0.10 (0.04–0.26)

Highly constrained

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

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.

3.12Z-score

OE missense 0.43 (0.36–0.51)

101 obs / 236.1 exp

Constrained

Highly missense-constrained (top ~0.1%)

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.0.10 (0.04–0.26)

0≤0.351.4

Missense OE?Ratio of observed to expected missense variants. OE ≤ 0.6 = fewer missense variants than expected by chance.0.43 (0.36–0.51)

0≤0.61.4

Synonymous OE?Control metric — synonymous variants are largely neutral and expected near OE = 1.0. Significant deviation may indicate annotation issues.0.97

0≤1.21.6

LoF obs/exp: 3 / 30.2Missense obs/exp: 101 / 236.1Syn Z: 0.24