Orphanet Journal of Rare Diseases | Two-Decade Population-Based Study of the Epidemiological Characteristics and Natural History of Porphyria in Taiwan

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This study, based on two-decade population data from Taiwan, systematically reveals the epidemiological features of porphyria, showing its incidence and prevalence are lower than in European countries, yet medical resource utilization is significantly higher than the general population, highlighting the importance of early diagnosis.

 

Literature Overview
This article, titled 'Epidemiological characteristics and natural history of porphyria – a twenty-year population-based analysis in Taiwan', published in the Orphanet Journal of Rare Diseases, reviews and summarizes the epidemiological features of porphyria in Taiwan between 2002 and 2022. Using the National Health Insurance Research Database (NHIRD) and rare disease registry data, the study analyzed information on gender, age at diagnosis, medical resource use, and mortality among 126 porphyria patients, revealing unique manifestations and disease burden in the Asian population and providing critical regional data for global porphyria research.

Background Knowledge
Porphyria is a group of rare inherited metabolic disorders caused by reduced activity of any enzyme in the heme biosynthesis pathway, leading to the accumulation of intermediate metabolites and resulting in acute neurovisceral attacks (e.g., acute intermittent porphyria, AIP) or cutaneous photosensitivity. Currently, diagnosis mainly relies on biochemical detection of elevated porphobilinogen (PBG) and delta-aminolevulinic acid (ALA) levels in urine, combined with genetic sequencing and counseling. Due to its rarity, epidemiological data vary significantly across regions, and nationwide studies in Asian populations have been lacking. This study fills that gap by systematically analyzing the incidence, prevalence, mortality, and medical resource utilization of porphyria in Taiwan, offering valuable empirical evidence for rare disease research. It also found that medical resource use is significantly increased among porphyria patients, especially in outpatient departments such as neurology, family medicine, and otolaryngology. Additionally, the mortality rate reached 1543.4 per 100,000, much higher than the general population. Therefore, enhancing awareness among physicians in various departments can aid in early diagnosis and treatment, reducing disease burden.

 

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Research Methods and Experiments
The study utilized the National Health Insurance Research Database (NHIRD) in Taiwan, linked with mortality and rare disease registry databases, to identify 126 patients diagnosed with porphyria between 2002 and 2022. It analyzed their demographic characteristics, annual incidence, prevalence, mortality, outpatient and inpatient department distribution, and frequency of medical visits. Diagnostic criteria included elevated urinary PBG and ALA levels, combined with plasma fluorescence scanning and genetic testing to ensure case accuracy.

Key Findings and Insights

• The annual incidence of porphyria in Taiwan ranged from 0.04 to 0.62 per million, with a prevalence of 5.15 per million in 2022, significantly lower than in European countries.
• 77% of patients were female, with a mean diagnostic age of 35.12 years, a mean follow-up duration of 10.32 years, and a mean age of death at 62.38 years.
• Mortality rate was as high as 1543.4 per 100,000, far exceeding the general population mortality rate of 672.6 per 100,000 in Taiwan.
• Medical resource utilization was significantly elevated, with higher average annual outpatient, emergency, and inpatient visits compared to the general population, particularly in neurology, family medicine, otolaryngology, and pediatrics.
• Most patients experienced non-specific symptoms before diagnosis, such as upper respiratory tract infection, contact dermatitis, and hypertension, suggesting challenges in early recognition.
• The study highlights AIP as the major subtype; however, some cases were classified as unspecified porphyria due to ICD coding limitations, requiring further genetic subtyping.

Significance and Future Directions
This study provides the first large-scale epidemiological data on porphyria in Asia, emphasizing the necessity of early diagnosis and multidisciplinary management. The introduction of RNAi therapeutics such as givosiran offers new treatment options for AIP, and future efforts could integrate neonatal screening and genetic testing to improve diagnostic rates. Additionally, the study suggests that training for primary care physicians should be enhanced to better identify patients with atypical symptoms and reduce misdiagnosis and treatment delay.

 

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Conclusion
This study, for the first time, systematically analyzed the epidemiological characteristics of porphyria using two decades of population-based data from Taiwan, revealing low incidence, high mortality, and substantial medical resource consumption among Asian populations. It underscores the importance of early diagnosis in reducing disease burden and improving patient outcomes. As porphyria patients often present with non-specific symptoms across multiple departments, increasing physician awareness can enhance diagnostic efficiency. Future studies may integrate genetic screening with novel therapeutic strategies such as RNAi therapy to further improve patient management.

 

Wei-Chih Wu, Yun-Hsuan Yeh, Chia-Chun Li, Chung-Hwan Chen, and Chih-Hsing Wu. Epidemiological characteristics and natural history of porphyria – a twenty-year population-based analysis in Taiwan. Orphanet Journal of Rare Diseases.