Madsen Jens Otto Broby, Sauer Sabrina, Beck Bodo, Johannesen Jesper
Herlev University Hospital, Department of Pediatrics, Herlev Ringvej, Herlev, Denmark.
University Hospital of Cologne, Institute of Human Genetics, Kerpenerstr, Cologne, Germany.
J Clin Res Pediatr Endocrinol. 2018 Mar 1;10(1):83-86. doi: 10.4274/jcrpe.4841. Epub 2017 Sep 6.
Idiopathic infantile hypercalcemia (IIH) was associated with vitamin-D supplementation in the 1950's. Fifty years later, mutations in the CYP241A gene, involved in the degradation of vitamin-D, have been identified as being a part of the etiology. We report a case of a 21-month old girl, initially hospitalized due to excessive consumption of water and behavioral difficulties. Blood tests showed hypercalcemia and borderline high vitamin-D levels. Renal ultrasound revealed medullary nephrocalcinosis. An abnormality in vitamin-D metabolism was suspected and genetic testing was performed. This revealed the patient to be compound heterozygous for a common (p.E143del) and a novel (likely) disease-causing mutation (p.H83D) in the CYP24A1 gene. The hypercalcemia normalized following a calcium depleted diet and discontinuation of vitamin-D supplementation. Increased awareness of the typical symptoms of hypercalcemia, such as anorexia, polydipsia, vomiting and failure to thrive, is of utmost importance in diagnosing IHH early and preventing long-term complications such as nephrocalcinosis. Further identification of as many disease-causing mutations in the CYP24A1 gene as possible can help identification of predisposed individuals in whom vitamin-D supplementation should be reconsidered.
特发性婴儿高钙血症（IIH）在20世纪50年代与维生素D补充剂有关。五十年后，参与维生素D降解的CYP241A基因突变已被确定为病因的一部分。我们报告了一例21个月大的女孩，最初因饮水过量和行为困难住院。血液检查显示高钙血症和临界高维生素D水平。肾脏超声显示髓质肾钙质沉着症。怀疑维生素D代谢异常并进行了基因检测。结果显示该患者在CYP24A1基因中为常见（p.E143del）和新的（可能）致病突变（p.H83D）的复合杂合子。采用低钙饮食并停止补充维生素D后，高钙血症恢复正常。提高对高钙血症典型症状（如厌食、烦渴、呕吐和发育不良）的认识，对于早期诊断IIH和预防肾钙质沉着症等长期并发症至关重要。尽可能多地鉴定CYP24A1基因中的致病突变，有助于识别那些应重新考虑补充维生素D的易感个体。
