PDF(Pubmed)
Abstract：
Carbonic anhydrase II deficiency is an extremely rare inborn error of metabolism that constitutes a triad osteopetrosis, renal tubular acidosis and intracerebral calcification. Unlike other subtypes of osteopetrosis, the presence of developmental delay and relative infrequency of skeletal fractures may not be a typical signs of symptoms indolent trajectory. This case report demonstrates a 11-year-old boy who had a bilateral midshaft tibial fracture despite low mechanism of injury. He was found to have severe respiratory distress with hypokalemia shortly after arriving to the emergency department venous blood gas (VBG) showed moderate metabolic acidosis. Potassium was corrected but he persistently had low potassium level despite frequent corrections. He was then started on sodium bicarbonate boluses. Whole exome sequencing (WES) was sent, and result was consistent with autosomal recessive osteopetrosis type III with renal tubular acidosis (RTA) evident by pathologic variant on CA2 gene confirming the diagnosis of carbonic anhydrase II (CA II) deficiency consistent with the unique Arabic mutation. Conversely, low mechanism of fracture injury in the context of severe form of fracture type should raise the concern of (CA II) deficiency especially in a pediatric patient who show no signs of developmental of cognitive delay.
摘要：
碳酸酐酶II缺乏是一种极其罕见的先天性代谢错误，构成三联体骨硬化，肾小管酸中毒和脑内钙化。与其他骨硬化亚型不同，发育迟缓和骨骼骨折的相对频率的存在可能不是症状惰性轨迹的典型迹象。此病例报告显示，一名11岁男孩尽管受伤机制较低，但双侧胫骨中段骨折。到达急诊科后不久，发现他患有严重的呼吸窘迫伴低钾血症静脉血气（VBG），表现为中度代谢性酸中毒。钾得到了纠正，但尽管经常纠正，他的钾水平仍然很低。然后他开始服用碳酸氢钠。发送了全外显子组测序（WES），结果与常染色体隐性遗传性骨质疏松III型伴肾小管酸中毒（RTA）一致，CA2基因的病理变异证实了碳酸酐酶II（CAII）缺乏症的诊断与独特的阿拉伯突变一致。相反，在严重骨折类型的背景下，骨折损伤的低机制应引起（CAII）缺乏的关注，尤其是在没有认知延迟发展迹象的儿科患者中。
