Protein tyrosine phosphatase non-receptor type 22 (PTPN22) gene R620W variant and sporadic idiopathic hypoparathyroidism in Asian Indians.

Recently, a gain of function variant C1858T of the lymphoid-specific protein tyrosine phosphatase non-receptor (LYP, PTPN22) gene has been reported to be associated with several autoimmune disorders including Graves' disease, type 1 diabetes, rheumatoid arthritis and vitiligo. The present study was carried out in 80 patients with sporadic idiopathic hypoparathyroidism (SIH) [43 males and 37 females, mean +/- SD age and duration of symptoms 32.5 +/- 14.1 years and 6.7 +/- 7.2 years (range 1 day to 35 years), respectively] and 193 healthy controls (male : female ratio 91:102, mean +/- SD age, 43.1 +/- 11.6 years) to assess association of 1858T allele with the disease. Polymerase chain reaction-restriction fragment length polymorphism analysis was performed to genotype C1858T variant. The frequency of occurrence of 1858T allele was 4/160 (2.5%) in SIH and 5/386 (1.3%) in the control alleles (odds ratio 1.95, 95% CI 0.51-7.37). Thus, the present study reveals that 1858T allele is rare (1.3%) in Asian Indians. The trend of higher prevalence of 1858T allele in patients with SIH needs to be studied further in other population with higher rate of the allele to support the autoimmune basis of the disease.