Abstract: Objective　To identify the mutations in the tissue DNA from patients with venous malformations or lymphatic malformations and to conduct genotyping for genetic diagnosis. Methods　Based on the next-generation sequencing, 55 tissues from different patients diagnosed as venous malformations or lymphatic malformations were analyzed. The tissues were sequenced in the exons area and part of the introns area of a customized panel for 2 types of mutations (point mutation and loss/insert of small fragments). Results　All 55 samples from 55 patients were collected and analyzed. Three probably driven mutations including 15 variable sites were identified. The most frequently mutated gene was TEK and PIK3CA. The most frequent variable site of TEK was L914F, and for PIK3CA were E542K and E545K. In patients whose tissues were detected as TEK mutations, 86.67% were venous malformations, and 100% involved venous malformation, while in those whose tissues were detected as PIK3CA mutations, 52.63% were KTS, 21.05% were lymphatic malformations and 94.74% involved lymphatic malformation. According to the genetic results, venous malformations and lymphatic malformations can be classified as TEK type, PIK3CA type, double mutations type, and non-mutation type. Conclusion　Gene mutations can be detected in venous malformations or lymphatic malformations. Venous malformations and lymphatic malformations can be classified as
TEK type, PIK3CA type, double mutations type, and non-mutation type. Gene tests can provide evidence of lesions involving venous malformation or lymphatic malformations.

Key words: Vascular malformation, 　Next-generation sequencing, 　Genotyping, 　Precision medicine