International School on Rare Diseases

Module 2 – Rare Diseases: Concepts & Systems (7 topics):
Introduction: 
This module introduces the core scientific, clinical, and systemic dimensions of rare diseases, providing the bridge between the public-health foundations of Module 1 and the One Health framework explored in Module 3. It offers a structured overview of how rare diseases are defined, diagnosed, managed, and supported across health-care systems, with emphasis on genetics, clinical pathways, therapeutic development, and patient experience.
Through this module, participants gain the analytical and practical competencies needed to understand rare diseases as complex, multi-layered conditions shaped by biology, care structures, societal factors, and policy environments.

8. Lecture/Module 2- Topic 1: Rare Disease Landscape: Introduction to the fundamental conceptual structure of rare diseases at the population level:
– Global definitions and classification of rare diseases, including variation across regions.
– Prevalence characteristics and why low prevalence creates unique public-health challenges.
– Epidemiological barriers, such as incomplete registries, underdiagnosis, and difficulty tracking incidence and prevalence.
– Data scenario” and the added value of data sharing in a FAIR ecosystem
– The Diagnostic Odyssey as a defining feature of rare conditions, including average time-to-diagnosis, common misdiagnosis patterns, and family/system burden.
– Stigma and Rare Diseases
– The landscape’s implications for policy, surveillance, and research priorities.

9. Lecture/Module 2- Topic 2: Clinical Genetics & Diagnostics: It covers the scientific and clinical tools needed to identify rare diseases:
– Overview of clinical genetics: Mendelian frameworks, inheritance patterns, penetrance, expressivity.
– Genomics in rare disease diagnosis, including whole-exome sequencing (WES), whole-genome sequencing (WGS), targeted panels, and RNA-based testing.
– Emerging diagnostic technologies, such as next-generation sequencing, methylation profiling, metabolomics, and bioinformatics.
– Ethical considerations in testing, including uncertain variants (VUS), incidental findings, consent, family testing, and genetic counseling.
– Integration of genetic diagnosis with clinical and imaging data to reduce diagnostic delays.

10. Lecture/Module 2-Topic 3: Care Access & Therapies: Focusing on the delivery side of rare-disease care:
– Navigation of healthcare systems, including referral pathways and the difficulty reaching specialists.
– Importance of Centers of Excellence and multidisciplinary teams (neurology, genetics, rehabilitation, metabolic disease, etc.).
– Overview of therapeutic approaches, including standard care, emerging biologics, gene therapy, enzyme replacement therapy, and individualized interventions.
– Geographic, socioeconomic, and systemic barriers to accessing care.
– Role of telemedicine and digital health tools in bridging access gaps. 

11. Lecture/Module 2-Topic 4: Clinical Trials & Orphan Drugs
This covers the research and regulatory pathway for treatments:
– Principles of designing clinical trials for small populations, including adaptive designs, natural history comparators, Bayesian modeling, and decentralized trials.
– Recruitment challenges and strategies in very small patient populations.
– Orphan drug development pathways, including incentives, regulatory frameworks (FDA/EMA), and accelerated approval mechanisms.
– Manufacturing and scale challenges specific to ultra-rare diseases.
– Ethical issues specific to trial participation in children and progressive neurodegenerative disorders.

12. Lecture/Module 2-Topic 5: Patient Experience & Advocacy: Explains the human experience of living with a rare condition:
– Quality-of-life (QoL) assessment in rare diseases (functional burden, emotional impact, caregiver strain).
– Tools and frameworks for measuring QoL across disease trajectories.
– The role of advocacy organizations, including education, fundraising, research facilitation, and policy impact.
– Patient empowerment and shared decision-making in care planning.
– The evolution of patient-partnered research, registries, and advisory boards.

13. Lecture/Module 2-Topic 6: Natural History & Disease Burden: Very important session outline explicitly explains the importance; this topic emerges naturally:
– Understanding the natural history of rare diseases: onset, progression, complications, lifespan, functional decline.
– Role of natural history in trial design, biomarker validation, and treatment development.
– Measuring disease burden across clinical, emotional, socioeconomic, and public-health dimensions. Burden of Disease Studies
– Importance of registries and longitudinal cohort studies, often created with strong patient-advocacy involvement.

14. Lecture/Module 2-Topic 7: Health Economics and RD Policy: This final topic addresses the system-wide implications of rare-disease care:
– Economic challenges of diagnosing rare diseases (e.g., cost of sequencing, specialist access).
– Cost-effectiveness and reimbursement for high-cost treatments (including gene therapies).
– Policy and legislative frameworks affecting rare-disease care (national plans, orphan drug acts, newborn screening expansion).
– Equity issues: global variation in access to diagnostics, treatments, and PEP (post exposure prophylaxis) for infections.
– Sustainability considerations for public-health systems.

Expected Outcomes
Upon completion of the module, participants are expected to:
a. Describe and understand the global rare-disease landscape and its public-health implications.
b. Apply principles of clinical genetics and advanced diagnostics to rare-disease evaluation.
c. Evaluate models of care delivery and therapeutic approaches for rare-disease patients.
d. Understand the limitations and modifications in the design, feasibility, and regulatory framework of rare-disease clinical trials.
e. Incorporate patient experience, advocacy perspectives, and real-world evidence into rare-disease management.
f. Interpret natural-history data, disease burden, and economic/policy factors influencing rare-disease systems.

Potential cases for discussion Module 2:
Case A — Juvenile GM1 Gangliosidosis (Childhood Onset)

Summary: Progressive neurodegenerative lysosomal storage disorder caused by beta-galactosidase deficiency due to pathogenic variants in GLB1. Typical onset in early childhood (often 3–5 years) with clumsiness, ataxia, dysarthria, learning difficulties, and later cognitive plateau or regression. MRI often shows cerebellar and mild cerebral atrophy with white-matter changes. Diagnosis is established by markedly reduced beta-galactosidase activity on leukocyte enzyme assay and confirmatory GLB1 sequencing. Emerging approaches include AAV9-mediated gene therapy delivering a functional GLB1 gene. Multidisciplinary supportive care (speech, occupational, physical therapy) is essential.
Teaching Points: Diagnostic odyssey; genotype–phenotype correlation; ethics and regulatory considerations for pediatric gene therapy; measuring functional outcomes.
Integration Lens: Access pathways to advanced diagnostics and trials; role of family advocacy.

Case B — Adult-Onset Mitochondrial Disease (MELAS)

Summary: Mitochondrial disease commonly involving m.3243A>G in MT-TL1. Presents in adolescence or adulthood with stroke-like episodes, seizures, hearing loss, headaches, diabetes, short stature, and possible lactic acidosis. Diagnosis uses mtDNA sequencing and occasionally muscle biopsy (ragged-red fibers). Management is supportive and multidisciplinary; some protocols use arginine or citrulline to mitigate stroke-like episodes.
Teaching Points: Maternal inheritance and heteroplasmy; registry-based natural history; coordination through centers of excellence; equity in access to genomics.
Integration Lens: Longitudinal burden measurement; cross-sector data sharing; adult care navigation.