一例原发性肾性糖尿患者的临床与基因突变分析
Clinical and Genetic Analysis of a Patient with Primary Renal Glucosuria
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摘要:目的 探讨1例原发性肾性糖尿(primary renal glucosuria, PRG)患者的临床表现及其分子生物学基础。方法 详细收集患者的临床资料、生化检查及影像学检查结果, 抽取外周静脉血, 提取基因组DNA, 聚合酶链反应(polymerase chain reaction, PCR)扩增SLC5A2基因的14个外显子及其与内含子的交界区, 测序确定突变情况。结果 患者临床表现、实验室检查和影像学检查符合PRG诊断。基因突变分析显示, 患者SLC5A2基因cDNA序列的第877位腺嘌呤A突变为胸腺嘧啶G(c.877 A>G), 造成第293位氨基酸由丝氨酸改变为半胱氨酸(p.Ser293Cys), 该突变位于SLC5A2的第7外显子。蛋白序列的保守性分析和突变蛋白的功能分析均表明p.Ser293Cys为致病性突变。结论 通过SLC5A2基因突变分析, 从分子遗传学方面证实患者PRG的诊断。临床上血糖正常的患者出现尿糖阳性且无其他近端肾小管功能障碍表现的患者应该考虑到该疾病可能, 基因分析有助于确诊。Abstract:Objective To analyze the clinical manifestations and molecular basis of a patient with primary renal glucosuria (PRG).Methods Clinical features, laboratory data, and imaging results were collected. Genomic DNA was extracted from leukocytes of peripheral blood of the patient. Fourteen exons of the PRG gene and their boundaries with introns were amplified by polymerase chain reaction (PCR). The mutations of the SLC5A2 gene were identified by direct sequencing.Results PRG was diagnosed on the basis of comprehensive consideration of clinical presentations, laboratory test results, and imaging findings. Gene mutation test revealed a nucleotide substitution of guanine for adenine at the position 877 of cDNA sequence of SLC5A2 gene (c.877 A>G), which caused a missense mutation of serine to cysteine at codon 293 (p.Ser293Cys). It occurred at the 7th exon of SLC5A2. Loci conservation analysis and functional prediction of missense mutation of SLC5A2 protein revealed that p.Ser293Cys was a pathogenic mutation.Conclusions SLC5A2 gene mutation analysis confirms the diagnosis of PRG in this patient from the aspect of molecular genetics.It is important to suspect PRG in patients with renal glucosuria and normal blood glucose in the absence of other manifestations ofproximal renal tubular dysfunction.Genetic analysis of SLC5A2 may be helpful to confirm the diagnosis.