Furthermore, NfL serves as potential prognostic marker in various diseases, as it is considered a predictor of disease activity in patients with multiple sclerosis (MS), as an early biomarker of neurological outcomes following cardiac arrest, as well as marker for cognitive worsening in Alzheimer`s disease (AD), frontotemporal dementia (FTD) and parkinson`s disease (PD), and of motor worsening in patients with amyotrophic lateral sclerosis (ALS) and atypical parkinsonian disorders (APDs)7,10. The gene discussed is NEFL; the disease is activated PI3K-delta syndrome.