The Clinical Features And Pathogenesis Of Hypoparathyroidism

Part 1.Clinical characteristics and genetic analysis of childhood-and adolescent-onset hypoparathyroidismIntroductionHypoparathyroidism is a relatively rare endocrine disease characterized by low serum calcium,elevated serum phosphorus and inappropriately normal or low concentrations of parathyroid hormone.Genetic deficiency is a major cause to the childhood-and adolescent-onset hypoparathyroidism.Until now,more than 10 candidate genes had been confirmed to be associated with hypoparathyroidism.Traditional Sanger sequencing is time-consuming and prohibitively labor-consuming for molecular diagnosis of hypoparathyroidism.ObjectiveTo study the clinical characteristics of childhood-and adolescent-onset hypoparathyroidism and to detect the disease-causing gene mutations in the patients by targeted next-generation sequencing(NGS).There were 11 candidate genes(AIRE、AP2S1、CaSR、CLDN16、FAM111A、GATA3、GCMB、PTH、TBCE、TBX1、TRPM6)in the targeted NGS panel.Methods The clinical data of 128 hypoparathyroidism patients with onset before the age of 18 years were collected and analyzed retrospectively.And we developed a targeted NGS platform that could allow detection of hypoparathyroidism candidate genes.Sanger sequencing or qRT-PCR were then performed to confirm the results of NGS.To the novel mutations,functional prediction was conducted by professional software.Results1.Clinical characteristics:Of all the 128 childhood-and adolescent-onset hypoparathyroidism patients,70 were male and 58 were female.The onset age of disease was 10(5-13)years old.And the duration was 6.0(2.3-14.4)years.The predominant features of the childhood-and adolescent-onset hypoparathyroidism were carpopedal spasm(89.3%)and seizures(66.1%).10 patients had deformities or other affected systems,2 cases had the falimily history.At the first visit to our center,the level of calcium and phosphorus was(1.68±0.32)and(2.41±0.62)mmol/l,respectively.PTH concentration was 3.0(3.0-4.2)pg/ml and the 24h urinary calcium was 1.50(0.81-2.84)mmol.Intracranial calcifications were identified in 89.4%of the patients.And 55.4%of the patients had cataract.Duration is an independent predictive factor for intracranial calcification(OR=1.483,P=0.011)and cataract(OR=1.115,P=0.005).All the patients were treated with calcium and vitamin D or its metabolites.Of 44 patients who were diagnosed with epilepsy,antiepileptic drug could be stopped in 39 cases(88.6%).Hypercalciuria was associated with serum calcium(P=0.016).2.Genetic analysis:Targeted NGS were performed in 49 childhood-and adolescent-onset hypoparathyroidism and 12 patients were identified genetic diagnosis(24.5%).Microdeletions of TBX1-COMT gene were found in 5 cases.5 cases were diagnosed with autosomal dominant hypocalcemia with hypercalciuria type 1(ADH1)for the mutations of CaSR gene.Of those,two novel gene mutations were identified[c.649G>T(p.D217Y)and c.349A>G(p.Q117R)].1 patient had a novel GATA3 gene mutation[c.286delT(p.W96Gfs*99)].And,these novel gene mutations were predicted to be deleterious by different softwares and conservation analyses.Another patient were diagnosed with Kenny-Caffey syndrome because of a hot FAM111A gene mutation[(c.1706G>A(p.R569H)].Conclusions1.Carpopedal spasm and seizures were the main manifestations of childhood-and adolescent-onset hypoparathyroidism.Calcium and vitamin D or its metabolites are effective.Monitoring the concentration of serum calcium and urinary calcium is of highly importance for the prevention of hypercalciruia.2.To the childhood-and adolescent-onset hypoparathyroidism patients with early onset age,development deformities or falimily history,genetic hypoparathyroidism is the major cause of the disease.3.Targeted NGS is a fast and accurate method to make molecular diagnosis of hyopoparathyroidism patients.Part 2.Pathogenesis research of Chinese adult-onset non-surgical hypoparathyroidismIntroductionHypoparathyroidism is a relatively rare endocrine disease.There are few studies focusing on the pathogenesis of adult-onset hypoparathyroidism.ObjectiveTo detect the disease-causing gene mutations in adult-onset hypoparathyroidism by targeted next-generation sequencing(NGS).And to explore the role of autoimmune factors in the pathogenesis of the disease by testing the calcium-sensing receptor antibodies.Methods78 patients with adult-onset nonsurgical hypoparathyroidism who were regularly followed at our center and recruited in the research:1.Exploring the suspicious genetic hypoparathyroidism by reviewing the family history,other affected systems and laboratory tests and 17 adult-onset hypoparathyroidism were selected because of hypercalciuria.Targeted NGS was performed in these patients to screen the candidate genes.2.The patients without gene mutation and 75 healthy objects were collected to test the calcium-sensing receptor antibodies by ELISA.Results1.Clinical characteristics:Of all the 78 adult-onset hypoparathyroidism patients,26 were male and 52 were female.The average onset age of disease was(34.4±11.8)years old.The duration was 4.5(1.0-13.0)years and the follow-up was 2.2(1.0-4.8)years.The predominant features of patients were carpopedal spasm(83.3%)and seizures(24.7%).At the first visit to our center,the level of calcium and phosphorus was(1.62±0.28)and(1.94±0.40)mmol/l,respectively.PTH concentration was 3.0(1.0-19.4)pg/ml and the 24h urinary calcium was 1.26(0.37-2.85)mmol.Intracranial calcifications were identified in 63.0%of the patients.And 77.3%of the patients had cataract.2.A novel homozygosis mutation of GCMB gene[c.130G>A(p.G44S)]was identified,which was predicted to be deleterious by Polyphen2 and conservation analyses.3.Comparing with the concentration of calcium-sensing receptor antibodies in healthy objects,the positive rate of calcium-sensing receptor antibodies was higher in the patients.Conclusions1.The genetic defect was only identified in 1 patient(5.9%).In adult-onset nonsurgical hypoparathyroidism without other diagnostic clues,the gene mutation screening as the first choice to clarify the etiology was not recommended.2.The autoimmune factor may play a role in the pathogenesis of adult-onset hypoparathyroidism.