Objective: To systematically investigate PIK3CA mutations in isolated macrodactyly. Methods: Overgrowth tissues from 12 isolated macrodactyly patients who were treated at Department of Hand Surgery, Beijing Jishuitan Hospital from May to August 2017 were collected during operation.There were 6 male and 6 female patients with average age of 4.5 years. DNA was tested for PIK3CA mutation using a targeted Sanger DNA sequencing method.Samples with negative Sanger result were tested with a next generation DNA sequencing(NGS)panel targeting 47 cancer hotspot genes including PIK3CA. Results: By targeted Sanger sequencing, PIK3CA mutations were detected in 9 of the 12 patients, with mutation level ranging from 7% to 27%.The PIK3CA mutations observed were p. His1047Arg, p.His1047Leu, p.Glu545Lys, and p. Glu542Lys.NGS found p. Glu453Lys in one additional patient, allowing the total positive rate to 10/12.All PIK3CA mutations detected in the study were cancer hotspot mutations.Among all tissue types tested, adipose tissue had the highest mutation detection rate(9/9), followed by nerve(10/12) and skin(10/12). Conclusions: A high proportion of isolated macrodactyly patients carry a PIK3CA mutation.Adipose, nerve, and skin are ideal tissue resources for PIK3CA mutation detection.Targeted Sanger sequencing with reflex to NGS represents a cost-effective strategy to test PIK3CA mutations in isolated macrodactyly.
目的： 研究单纯性巨指(趾)患者的PIK3CA基因突变位点。 方法： 前瞻性系统研究2017年5—8月在北京积水潭医院手外科就诊的12例单纯性巨指(趾)患者的临床资料。患者男性6例，女性6例，平均年龄4.5岁。手术中切除单纯性巨指(趾)患者的病变组织，采用改良的Sanger DNA测序方法来检测PIK3CA基因突变。对Sanger测序结果阴性的患者样本采用下一代测序(NGS)。 结果： 12例患者中，9例经Sanger DNA测序检测到PIK3CA基因突变，突变水平在7%～27%。突变的位点包括p.His1047Arg、p.His1047Leu、p.Glu545Lys和p.Glu542Lys。NGS又发现1例携带p.Glu453Lys的患者。12例患者中，PIK3CA基因突变阳性者10例。在收集的病变组织检查中，脂肪组织中突变率最高(9/9)，其次是皮肤和神经组织(5/6)。 结论： PIK3CA基因突变率在单纯性巨指(趾)中极高。受累脂肪、神经及皮肤组织均为理想的基因检测组织来源。Sanger测序目标基因片段可经济适用地检测单纯性巨指(趾)基因突变。.
Keywords: Foot deformities; Hand deformities; Macrodactyly; PIK3CA.