One widely studied **continuous health indicator** that can be predicted from gene expression is **Biological Age** (also called **Epigenetic Age** or **Transcriptomic Age**).  

### **Why Biological Age?**
- Unlike chronological age, **biological age** reflects the physiological state of an individual, capturing aging-related changes at the molecular level.
- It can be estimated using **gene expression data**, particularly from transcriptomic or epigenetic markers.
- Studies have developed **transcriptomic age predictors** using machine learning on large-scale gene expression datasets.