Analyse The 5' Flanking Of NKCC1 And Renin Gene In Patients With Thyrotoxic Periodic Paralysis

Background and ObjectiveThyrotoxic periodic paralysis (TPP) is a complication of thyrotoxicosis.It manifests as a paralytic episode commonly associated with hypokalaemia.The Asian young males have priorty to suffer this disease.The overall incidence ratio of TPP between males and females is as high as 17-70:1. But Caucasians seldom suffer this disease.The significant differences in gender and dictric indicate that genetic factor plays a central role in pathogenesis of TPR.Although scientists had done lots of studies about TPP, until now the real pathogenesis remains unclear.Five subtypes of sodium-potassium ATPase genes,β2-adrenergic receptor gene and associated genes with Familial hypokalemic periodic paralysis(FHPP) have been studied and no mutations were found associated with TPP.Sodium-potassium-chloride cotransporter1( NKCC1) exit in many tissues and cells membrane including skeletal muscle cells.In the resting conditions,NKCC1 mediates nearly 15% intracelluar shift of serum potassium.When skeletal muscle contracting or stimulated by the catechol NKCC1 mediating intracelluar shift of serum potassium will increased up to 35%.Insulin also can stimulate the NKCC1 in vitro clutivated rat muscle cells.Because the skeletal muscle contains mostly of potassim in vivo,we can deduce that NKCC1 play an important role in regulating potassium equilibrium.What's more,a porption of TPP patients' RASS is activited,and Japanses scientists Kobori has found thyroid hormone can sitimulate the renin gene expression and there is a thyroid hormone reponse element in the 5' flanking region of renin gene.However,he real reason of hypokalemia is that a large amount of excelluar posstium shift into intracelluar fluid,the TPP patients' high level of renin maybe associated with the pathogenesis of TPP.Through the thyroid hormone receptor(TR) thyroid hormone enduces its biochemical function,thyroid hormone regulates genes with promoters that contain multiple thyroid hormone reponse elements(TRE),TRE are bulit from one or more copies of a sequence that macths a consensus motif:5'AGGTCA3'.What's more,the periodic paralysis is closely aossioateed with the patient's thyroid funtion,that meas when hyerthyroidrism,the paralysis usually occoured,when thyroid funtion become normal,the paralysis stops to occour.So Increased NKCC1 gene and renin gene is postulated to contribute to the hypokalaemic paralytic attacks in TPP.The aim of this study was to determine the genetic predisposition to TPP in relation to NKCC1 geneand renin gene.At the same time to conclude the clinical features ,diagnosis,therapy and pathogenesis of TPP.Materials and MethodsA case-control genetic association study was carried out to determine the role of mutation/polymorphism in NKCC1 gene and renin gene in the pathogenesis of TPP.Patients 56 TPP patients were compared to 71 male Graves' disease (GD) patients without TPP and 73 normal controls.First,using the promoter analysis software and gene reponse elements predicting software in the web to find out the promoter and thyroid hormone response element in 5' flanking region of NKCC1 gene and renin gene.Then genomic DNA was extracted from peripheral blood samples.Polymerase chain reactions (PCR) were performed to amplify the NKCC1 gene and renin gene 5' flanking regions. The products of PCR before directly secquenced are need to be purified,then by using the DNAMAN software to analysis the secquence to find out the mutations and singnal nuclcotide polymorphisms(SNP) which are postulated to be associated with TPP occured.Results No mutations were detected in the promoter regions vicinity of the thyroid hormone response element of renin gene in any of the patients or normal controls studied There were no mutations in the 5' flanking region vicinity of the thyroid hormone response element of NKCC1 gene bewteen the three groups of subject.In the study,we found the weight and BMI,the age of onset and the serum thyroid hormones levels between the TPP patients and simple hyperthyrosis patients have find no statistics differences.But the incidence of the ophthalmpathy,thyroid gland goiter ,the typical symptoms of hyperthyroidism of hyperthyrosis patients is hinger than the TPP patients,but the serum potassium level of hyperthyrosis patients is lower than the TPP patients.ConclusionNo pathogenic mutation in NKCC1 gene and renin gene 5' flanking region was found in the Henan Province TPP patients.No association between the polymorphisms of NKCC1 genesand renin gene and TPP could be detected.The pathogenesis of TPP need us to do more studies.