CAG Repeats in the Androgen Receptor Polymorphism do not Correlate with Thyrotoxic Periodic Paralysis

Background: Thyrotoxic periodic paralysis (TPP) occurs mostly in males, but no studies have addressed the role of androgen in the disease. Hyperinsulinemia can precipitate acute paralysis in TPP patients. CAG repeats in the androgen receptor (AR), an X-linked gene, correlate with serum insulin levels. Aim: To evaluate whether CAG repeats in the AR gene might predict the susceptibility to TPP in Korean male Graves' patients. Methods: We evaluated CAG repeat length in a series of 33 male TPP patients and 48 control patients by direct sequencing of the PCR product of the AR promoter site. Control patients were male Graves' patients without a history of paralysis. Results: The CAG repeat length varied from 15 to 34 (median of 23). The upper quartile of CAG length was equal to or above 26 repeats (long AR). The distribution of long AR was 0.30 in TPP and 0.15 in control patients, respectively (odds ratio, 2.51; 95% confidence interval, 0.92~6.85; P = 0.09). Conclusion: AR gene polymorphisms may not confer genetic susceptibility to TPP in Korean male patients with Graves' disease. (J Korean Endocr Soc 23:117~122, 2008)