The role of deiodinase type 1 polymorphism, rs11206244 (C785T), in clinical management of a sample of Iraqi hypothyroidism patients treated with levothyroxine

Abstract

BackgroundLevothyroxine (LT4) is the drug that is frequently recommended for the treatment of hypothyroidism. Many patients still have symptoms and disease-complaints even after a long time of maintaining treatment with this drug. Deiodinase type1 (DIO1) gene encodes for the DIO1 enzyme that regulates the metabolism of thyroid hormones and LT4 as well. Polymorphisms in this genes could be responsible for altered DIO1 enzymatic activity and accordingly altered response to LT4. MethodsA total of 220 primary hypothyroidism unrelated female patients aged 40 years and above were enrolled in this cross-sectional study. The single nucleotide polymorphism (SNP) rs11206244 (C785T) in the DIO1 gene was detected using tetra primers amplification refractory mutation system polymerase chain reaction (tetra ARMS PCR) technique. The thyroid hormones (thyroxin (T4), triiodothyronine (T3), reverse triiodothyronine (rT3) and diiodothyronine (T2)) and thyroid stimulating hormone (TSH) in addition to some glycemic indices were determined. ResultThe distribution of the rs11206244 (C785T) alleles indicated the prevalence of the C allele, the genotype frequency was106 (48.2%) for CC, 75 (34.1%) for CT and 39 (17.7%) for TT. The patients were divided into three groups according to their detected genotype. Both TSH and rT3 were elevated in the carriers of T allele (p = 0.018 and p = 0.028, respectively). There were no significant differences in the other thyroid hormones (T3, T4 and T2) among the three groups. The glycemic indices were in close limits among the three groups of the patients as well. ConclusionSince the rs11206244 (C785T) SNP of DIO1 gene has no impact on the T3 and T4 hormones levels, this SNP could has no contribution to the therapeutic response to LT4 in our sample of Iraqi hypothyroidism female patients. However, this SNP could be associated with the decreased clearance of rT3 from the body.