## 3 Structure, Scope, and Methodology in Expert System Design for FSGS
### Scope of Support and Operation of System Modules  
The decision support and classification expert system for FSGS is built on a modular, hierarchical structure that systematically addresses the various stages of diagnosis, treatment, and follow-up. Designed with input from clinical guidelines and specialist knowledge, the system aims to ensure adaptability, precision, and ease of use for healthcare professionals. The system integrates a user-friendly graphical interface to assist clinicians in navigating diagnostic and therapeutic pathways. Interactive prompts and visual representations ensure clarity in decision-making (see Figure 1).  
The primary components include:  
* Diagnostic workflow (Diagnosis of FSGS module)--the system identifies essential diagnostic steps, including detailed medical history, laboratory evaluations, imaging, and kidney biopsy when indicated. For cases where a biopsy is required, the system outlines the necessary steps. In addition, it provides recommendations on how to interpret biopsy results to differentiate between primary FSGS, secondary causes, or genetic variants.The system also supports the selection of diagnostic tests tailored to the patient's clinical presentation. Suggested tests include markers for inflammation, kidney function, and proteinuria, alongside specialized investigations for underlying or secondary causes (e.g., viral infections, autoimmune diseases). For suspected genetic predispositions, it highlights indications for genetic testing.
* Therapeutic recommendations (management and treatment module)--treatment is customized based on disease presentation and risk stratification. Conservative management includes lifestyle modifications, nephoprotective measures such as dietary sodium restriction, and pharmacological options like ACE inhibitors or ARBs to control proteinuria and blood pressure. Active treatment is used in progressive or severe cases, where the system proposes induction therapies, such as immunosuppressive agents (e.g., corticosteroids or calcineurin inhibitors), and provides schedules for monitoring treatment effectiveness.
* Outcome monitoring (final classification module)--after initiating treatment, the system evaluates progress using clinical markers and patient-reported outcomes. This step allows for adjustments in management, ensuring treatment aligns with the patient's response and tolerability. The system does not only assess proteinuria reduction but also considers kidney function, albumin levels, and other relevant parameters. Using ML and AI, the FSGS status is determined based on various features from the classes corresponding to the patient's condition.
* Treatment adaptation (treatment continuation module)--when standard therapy fails or produces suboptimal results, the system guides clinicians in modifying or escalating  
Figure 1: Overview of the modules of the expert system.  
treatment. This includes second-line therapies and participation in clinical trials where appropriate.
* Follow-up strategies (FSGS analysis module)--long-term care is a vital component, with the system providing protocols for monitoring remission, detecting relapses, and minimizing complications. Regular laboratory assessments and clinical evaluations are scheduled to maintain optimal kidney function and address any emerging issues promptly.