Thiopurine Methyltransferase Levels and Azathioprine Outcomes in Thai Patients with Cutaneous Autoimmune Diseases
Issued Date
2026-01-01
Resource Type
eISSN
11787015
Scopus ID
2-s2.0-105037578433
Journal Title
Clinical Cosmetic and Investigational Dermatology
Volume
19
Rights Holder(s)
SCOPUS
Bibliographic Citation
Clinical Cosmetic and Investigational Dermatology Vol.19 (2026)
Suggested Citation
Pureesrisak P., Kwangsukstid O., Kattipathanapong P., Kootiratrakarn T., Sukasem C., Mairiang D., Channakorn W., Phainupong D., Suphannaphong M. Thiopurine Methyltransferase Levels and Azathioprine Outcomes in Thai Patients with Cutaneous Autoimmune Diseases. Clinical Cosmetic and Investigational Dermatology Vol.19 (2026). doi:10.2147/CCID.S596438 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/116632
Title
Thiopurine Methyltransferase Levels and Azathioprine Outcomes in Thai Patients with Cutaneous Autoimmune Diseases
Corresponding Author(s)
Other Contributor(s)
Abstract
Background: Thiopurine methyltransferase (TPMT) is responsible for the inactivation of azathioprine, and is widely used to treat cutaneous autoimmune diseases. TPMT activity is inherited as an autosomal codominant trait and ranges from high to undetectable levels in different individuals. Low TPMT activity may result in a higher risk of adverse effects (AEs), whereas high TPMT activity may result in potential treatment failure. Objective: To assess TPMT levels in patients with cutaneous autoimmune diseases and evaluate the correlation between TPMT levels and AEs of azathioprine and clinical response in patients with pemphigus. Methods: A cross-sectional study was conducted in 300 patients with cutaneous autoimmune diseases. Blood samples were collected to identify TPMT levels by ELISA. In 10 patients with the lowest TPMT levels, subsequent PCR analysis for the TPMT genotype was performed. Results: Among 300 patients, pemphigus vulgaris was diagnosed in 93 (31%), lupus erythematosus in 93 (31%), pemphigus foliaceus in 39 (13%), bullous pemphigoid in 32 (10.7%), systemic sclerosis in 26 (8.7%), and other diseases in 17 (5.6%). The mean TPMT level was 84.9 ± 30.5 mU/mL. Alcohol consumption significantly correlated with lower TPMT levels (p = 0.005). TPMT levels were not correlated with AEs (p = 0.184). The TPMT genotype showed TPMT*1/*1 (wild-type) in all 10 patients with the lowest TPMT levels. In the pemphigus group, the TPMT level did not correlate with clinical response (p = 0.363). Conclusion: Alcohol consumption resulted in lower TPMT levels. TPMT levels did not correlate with clinical response in the pemphigus group and AEs. These findings provide real-world clinical insight in Thai patients, where routine TPMT screening is not universally implemented, highlighting the need for alternative predictors of azathioprine toxicity.