九例PKHD1基因突变患者的表型分析

Phenotype analysis of 9 cases with mutations in PKHD1 gene

目的总结9例PKHD1基因突变患者的临床特征，进一步提高对该基因突变所致表型谱的认识。方法收集2011年1月至2016年12月期间于复旦大学附属儿科医院泌尿系统疾病诊治中心收治的9例PKHD1基因突变患者的临床资料，包括病史特点、相关实验室检查、影像学和家族史等资料。9例患者采用外显子捕获的方法对4000种人类单基因病的相关致病基因（例1～4）或全外显子（例5～9）进行高通量测序，按照高通量测序变异筛查流程进行测序数据分析，发现9例患者均存在PKHD1基因变异，未发现。肾单位肾痨等疾病致病基因的突变。利用文献检索、相关国际数据以及生物信息学对PKHD1基因变异进行分析，确定每一变异位点为报道的致病性突变或预测为有害性突变。Sanger法对PKHD1基因突变结果进行验证，在家系中进行突变分析，并进行相关文献复习。结果9例患者中，男性5例，女性4例，平均发病年龄2．6岁（0．5-5．2岁）。肾脏B超提示，9例患儿肾脏均有囊肿形成，其中6例双肾脏体积增大，1例肾脏大小正常，1例慢性肾脏病5期双侧肾萎缩；2例血管受累，表现为肾动脉狭窄；1例肺部受累，表现为左侧主支气管局灶狭窄；1例有膀胱输尿管反流。9例PKHD1基因突变者中，3例为纯合突变，6例为复合杂合突变，无义突变1个，移码突变1个，错义突变15个。2例有3个杂合突变，2例有c．5935C〉T突变，另2例有c．5869G〉A突变，其他患者有各不相同的突变。共发现lO个新的突变位点。结论PKHD1基因突变的患者不仅肾脏体积可不增大，甚至可以萎缩。。肾动脉狭窄、膀胱输尿管反流、支气管狭窄均是首次在PKHD1基因突变患者中报道。PKHD1基因无热点突变，新发现的13．274C〉T、c．9059T〉C、c．8996delG、c．281C〉T、c．10424T〉A、c．7092T〉G、c．4949T〉C、c．5869G〉A、c．6197A〉G和c．1877A〉G突变进一步丰富了PKHD1基因突变谱。

Objective To summarize the clinical features of 9 cases with mutations in PKHD1 gene for a better understanding of its phenotype. Methods Clinical data of nine cases with mutations in PKHD1 gene were summarized from January 2011 to December 2016 in our center, including clinical manifestations, laboratory findings, imaging data and family investigation. Next generation sequencing was used to screen 4000 genes in case 1 to 4 and whole exons in case 5 to 9. Significant variants detected by next generation sequencing were confirmed by conventional Sanger sequencing. Segregation analysis was performed using parental DNA samples. Relevant literature was reviewed. Results Among these 9 cases, 5 are male, 4 are female. The average age of onset was 2.6 years old （ranging from 0.5-5.2 years）. Renal ultrasound revealed that all 9 cases had cysts in bilateral kidney, 7 cases with enlarged kidney, 1 case with normal size kidney, 1 case with normal size kidney,and 1 case with bilateral renal atrophy. Two cases with renal artery stenosis, 1 case with focal narrowing in left main branch and 1 case with vesico-ureteral reflux were found. Among the 9 cases, 3 cases had homozygous mutations, and 6 cases had compound heterozygous mutations, including 1 nonsense mutation, 1 frameshift mutation and 15 missense mutations. There were 2 cases with 3 heterozygous mutations, 2 c.5935C 〉 T mutations and 2 cases with C. 5869G 〉 A mutations. A total of 10 new mutations were identified. Conclusion Patients with mutations in the PKHD1 gene had normal size kidney, or even atrophic kidney. Renal artery stenosis, vesicoureteral reflux and bronchial stenosis were all first reported in patients with mutations in PKHD1 gene. The novel mutations, c.274C 〉 T, c.9059T 〉 C, c.8996delG, c.2g 1C 〉 T, c. 10424T 〉 A, c.7092T 〉 G, c.4949T 〉 C, c.5869G 〉 A, c.6197A 〉 G and c.1877A 〉 G further expanded the mutation spectrum of PKHD1 gene.