Objective: The purpose of this study was to investigate the relationship between genotypes and clinical phenotypes of primary distal renal tubular acidosis (dRTA) in children. Methods: Clinical information, genetic testing information and follow-up data (until March 2021) of children with dRTA from Children's Hospital of Chongqing Medical University (from January 2010 to December 2020) were analyzed retrospectively. According to different pathogenic genes, patients were divided into SLC4A1 gene and ATP6V0A4+ATP6V1B1 gene groups. Age at onset, clinical manifestations and laboratory findings were compared. Self-comparisons of height standard deviation score (HtSDS), weight standard deviation score (WtSDS), blood pH and serum potassium before and after treatment were tested. T-test, Fisher's exact test and rank sum test were used to analyze among groups. Results: Among 27 children with dRTA (16 boys and 11 girls), the age of onset was 33.4 (10.0, 36.0) months.There were 22 patients (81%) with SLC4A1 gene variation, 3 patients (11%) with ATP6V1B1 gene variation and 2 patients (8%) with ATP6V0A4 gene variation. Totally 22 patients (81%) with renal calcium deposition, 19 patients (70%) hypokalemia, 18 patients (67%) short stature, 16 patients (59%) malnutrition, 16 patients (59%) rickets, and 15 patients (56%) polydipsia and polyuria. Noteworthily, the genotyping results indicated that the age at onset in SLC4A1 gene group was older than that in ATP6V0A4+ATP6V1B1 gene group, with a statistically significant difference (27.3 (12.0, 36.0) vs. 8.2 (2.5, 15.0) months, H=6.33, P=0.012). However, there were no significant differences in clinical manifestations or laboratory test results (all P>0.05). Furthermore, the course of disease was 3.9 (1.3, 6.0) years and the follow-up period was 3.1 (1.0, 4.5) years in 27 patients. In addition, there were no significant differences in recovery rate of clinical manifestations and last laboratory findings between SLC4A1 gene group and ATP6V0A4+ATP6V1B1 gene group (all P>0.05). HtSDS and WtSDS of those patients significantly increased after treatment (-3.2±1.9 vs. -2.1±1.1, -2.5±1.5 vs. 0±1.9, t=-2.94, -5.44, both P<0.01). Serum K+ and blood pH were restored eventually ((3.2±0.5) vs. (4.0±0.5) mmol/L, 7.27±0.07 vs. 7.37±0.07, t=-4.92, -5.25, both P<0.01). Totally 14 patients had normalized serum potassium, 12 patients had normalized blood pH, but only 4 patients had normalized serum bicarbonate concentration and normal base excess. Conclusions: The age of onset of patients who had SLC4A1 gene mutation was older than that of patients with ATP6V0A4 gene and ATP6V1B1 gene mutations. However, there was no obvious correlation between the condition and prognosis of the dRTA patients and pathogenic genes. Early diagnosis, early treatment, regular follow-up and timely adjustment of the dosage of medication can significantly improve the prognosis of dRTA in children. Serum bicarbonate concentration and actual base excess might not be the necessory indicators to assess clinical recovery.
目的： 分析原发性远端肾小管酸中毒（dRTA）患儿的临床特点及基因型和临床表型的关系。 方法： 回顾性分析重庆医科大学附属儿童医院2010年1月至2020年12月诊断的27例dRTA患儿的一般情况、临床表现、实验室检查、基因检测及随访（截至2021年3月）等临床资料。根据致病基因不同分为SLC4A1基因组和ATP6V0A4+ATP6V1B1基因组，比较不同基因型组患儿起病年龄、临床表现和实验室检查结果。同时比较患儿治疗前后身高标准差积分、体重标准差积分和血pH值、血钾浓度等。组间比较采用t检验、Fisher确切概率法、秩和检验。 结果： 27例dRTA患儿中男16例、女11例，起病年龄33.4（10.0，36.0）月龄。22例（81%）SLC4A1基因变异，3例（11%）ATP6V1B1基因变异，2例（8%）ATP6V0A4基因变异。22例（81%）患儿有肾脏钙质沉积，19例（70%）有低钾表现，18例（67%）有身材矮小，16例（59%）有营养不良，16例（59%）有佝偻病，15例（56%）有多饮、多尿等临床表现。SLC4A1基因组患儿起病年龄大于ATP6V0A4+ATP6V1B1基因组［27.3（12.0，36.0）比8.2（2.5，15.0）月龄，H=6.33，P=0.012］，临床表现、实验室检查结果差异均无统计学意义（均P>0.05）。27例患儿病程3.9（1.3，6.0）年、随访3.1（1.0，4.5）年。SLC4A1基因组和ATP6V0A4+ATP6V1B1基因组临床表现恢复率及末次实验室检查结果差异均无统计学意义（均P>0.05）。治疗后患儿身高标准差积分、体重标准差积分均较治疗前升高（-3.2±1.9比-2.1±1.1、-2.5±1.5比0±1.9，t=-2.94、-5.44，均P<0.01）。血钾及pH值均较治疗前上升［（3.2±0.5）比（4.0±0.5）mmol/L、7.27±0.07比7.37±0.07，t=-4.92、-5.25，均P<0.01］。14例患儿血钾恢复正常，12例血pH值恢复正常，仅4例血清碳酸氢根浓度、实际碱剩余恢复正常。 结论： SLC4A1基因变异的dRTA患儿起病年龄晚于ATP6V0A4和（或）ATP6V1B1基因变异患儿，病情及预后与致病基因无相关性。早诊断、早治疗、规律随访、及时调整用药可改善患儿预后，提高患儿生存质量。血清碳酸氢根浓度、实际碱剩余可能不是评估临床恢复的必备指标。.