Diverse Genetic Aetiologies and Clinical Outcomes of Paediatric Hypoparathyroidism

Ja Hye Kim; Young-Lim Shin; Seung Yang; Chong Kun Cheon; Ja Hyang Cho; Beom Hee Lee; Gu-Hwan Kim; Jin Ok Lee; Eul Joo Seo; Jin-Ho Choi; Han-Wook Yoo

Disclosures

Clin Endocrinol. 2015;83(6):790-796. 

In This Article

Methods

Study Subjects and Clinical Measurements

Our current retrospective study included 37 patients (23 males, 14 females) with primary hypoparathyroidism who were diagnosed prior to 18 years of age between 1989 and 2013. Clinical features and biochemical findings, including presenting symptoms, medications, adverse events, serum total calcium, ionized calcium, phosphorus and creatinine levels, were analysed retrospectively. Intact PTH levels were measured using an immunoradiometric assay kit (Total Intact PTH Kit, IBL International GMBH, Hamburg, Germany). The diagnosis of hypoparathyroidism was made based on biochemical findings of serum calcium levels below the reference range with low or inappropriately normal PTH levels.[2] The normal range for intact PTH was 1–6·5 pmol/l, and overt hypoparathyroidism was defined as a PTH level below 1 pmol/l with hypocalcaemia.[8] Renal ultrasonography was performed on 26 patients, and brain computed tomography scans were carried out on 15 patients.

Cytogenetic and Molecular Analyses to Identify the Aetiology of Hypoparathyroidism

Chromosome 22q11.2 microdeletion syndrome was confirmed by fluorescence in situ hybridization (FISH) analysis using peripheral blood lymphocytes. FISH analysis was performed using commercially available FISH probes manufactured by Vysis (Downers Grove, IL, USA). FISH probes targeted the DiGeorge syndrome critical region (TUPLE1) and a 22q terminal probe (ARSA) that binds to 22q13 was used as a control probe. Molecular analysis was performed on selected patients with a clinical suspicion of a monogenic hypoparathyroidism disorder after obtaining informed consent. Genomic DNA was extracted from peripheral blood leucocytes using a Gentra Puregene Blood Kit (Qiagen, Hilden, Germany). All coding exons and exon/intron boundaries of the GATA3,AIRE,TBCE,FAM111A and mitochondrial genes were amplified by polymerase chain reaction (PCR). PCR products were directly sequenced using an ABI3130x1 Genetic Analyser (Applied Biosystems, Foster City, CA, USA).

Statistical Analyses

Data are presented as the mean ± standard deviation. Statistical analyses were performed using SPSS for Windows version 21.0 (SPSS, Chicago, IL, USA). Categorical variables were analysed using the Mann–Whitney U-test. Associations between clinical symptoms at presentation and overt hypoparathyroidism were analysed with Fisher's exact test. P-values <0·05 were considered statistically significant.

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