A case of tuberous sclerosis induced by a somatic mosaic mutation in the TSC2 gene

Abstract

Objective To investigate clinical features and detect mutations in a case of tuberous sclerosis complex (TSC) caused by a somatic mosaic mutation in the TSC2 gene. Methods Peripheral blood samples were obtained from a patient with suspected TSC, his parents, and 200 unrelated healthy controls. Genomic DNA was extracted from these blood samples, polymerase chain reaction (PCR) and next-generation sequencing were performed to amplify all the exons and their flanking sequences of the TSC1 and TSC2 genes followed by DNA sequencing, so as to identify mutations in the TSC1 and TSC2 genes. DNA was also extracted from lesional skin tissues of the patient, and PCR was conducted to amplify the target fragment of the TSC2 gene followed by DNA sequencing. Results The patient clinically presented with facial angiofibroma, depigmented patches on the waist, periungual fibroma and angioleio-myolipoma of the kidney, which were consistent with the diagnosis of TSC. A mutation c.5130_5131insT (p.V1711Cfs*18) was identified in the TSC2 gene in the patient. A higher frequency of the mutation was found in the DNA of the tumor tissue than in that of the peripheral blood. No such a mutation was found in his parents′ DNA, unrelated healthy controls or any public database. Conclusion The somatic mosaic mutation c.5130_5131insT in the TSC2 gene is responsible for the phenotype of TSC in the patient. Key words: Tuberous sclerosis complex; Mosaicism; TSC2 gene