**4. Conclusion**

The achievements in the last two decades in the diagnosis, management and research on rare diseases have been unprecedented. The advancing studies of rare diseases toward genetic causes and effective therapies have been progressing rapidly.

Policies and guidelines concerning rare diseases have been issued in different regions and countries. Life quality of patients with rare diseases has been improving with such advances internationally.

Increases in research funding support have been providing more and more coordination in different disciplines/areas of management to provide the forming of best practice.

Awareness of rare disease has been raising quality of life, and the ensuing impact on patients has been improving, although we are still facing challenges in medical and nonmedical issues.

Challenges from medical and nonmedical issues have been reducing with more knowledge and awareness of rare diseases in the community/society in the healthcare strategies and established in vitro diagnostic and bioinformatics systems.

Further and deep studies on rare diseases across different levels and aspects, including the cell types, tissues and organs, are associated with rare diseases and the interactions between different cell types to explore mysteries.

Rare disease is named historically with the limitation of technologies in the symptomatic era under the condition from clinical data to distinguish from the common diseases, such as nutritional and infectious diseases which were relatively and predominantly higher.

However, it is believed that more rare diseases will be identified and reclassified in the future in the genomic era since we know that "rare disease" is probably not a proper terminology to be used currently to classify such a disease genetic base affecting such a large population worldwide.
