Features include always present findings: Gait ataxia, Failure to thrive, Overactive reflexes (hyperreflexia), and Axial hypotonia and others; and common findings: Bilateral tonic-clonic seizure, Crouch gait, Delayed CNS myelination, and Moderate intellectual disability and others.

FZR1 encodes fizzy and cell division cycle 20 related 1 (496 aa). Substrate-specific adapter for the anaphase promoting complex/cyclosome (APC/C) E3 ubiquitin-protein ligase complex. Highest expression in Brain Cerebellum (72.5 TPM) and Testis (70.1 TPM).

Developmental and epileptic encephalopathy 109 is associated with mutations in the FZR1 gene on chromosome 19.

The FZR1 protein participates in APC/C:Cdh1-mediated degradation of Skp2 and CDKN1A (p21) prevents association of Cyclin A:Cdk2 with Cdh1 pathways.

FZR1 is classified as a druggable target (Dna Repair category) with score 0.0.

Genetic testing for FZR1 is available. Testing is considered confirmatory for diagnosis.

Biomarker and diagnostic research for developmental and epileptic encephalopathy 109 has been reported in the published literature.

Phenotype severity distribution: 12 always present features, 16 common features.

No clinical trials have been registered for developmental and epileptic encephalopathy 109.

10 publications have been identified in PubMed for developmental and epileptic encephalopathy 109. Research spans Case Report / Case Series (30%), Basic Science / Preclinical (30%), and Epidemiology / Natural History (30%).