A novel de novo splicing mutation c.1444-2A>T in the TSC2 gene causes exon skipping and premature termination in a patient with tuberous sclerosis syndrome

Preliminary Screening of a Familial Tuberous Sclerosis Complex Pathogenic Gene

Purpose

The aim of this study was to screen the possible pathogenic genes of one family with tuberous sclerosis complexes (TSCs).

Patients and Methods

All family members were examined through detailed clinical evaluations, auxiliary examinations and CT. Then, we selected five members from this TSC family as the test samples. They were analysed by a new exon group sequencing method. Single nucleotide polymorphisms (SNPs) were screened by using databases, such as dbSNP and HAPMAP, and then the candidate genes were selected. Genes were analysed, and finally, the most likely mutation sites were screened. The results were examined by Sanger sequencing.

Results

In this TSC family, we identified c.913+2T>G, a splicing site mutation in the 9th intron region of TSC1. Family members without TSC did not have this mutation.

Conclusion

The mutations in the intron regions cannot be ruled out as a pathogenic factor for TSC.

A second hit somatic (p.R905W) and a novel germline intron-mutation of TSC2 gene is found in intestinal lymphangioleiomyomatosis: a case report with literature review

BACKGROUND

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by hamartomas in multiple organs associated with germline mutations in TSC1 and TSC2, including exonic, intronic, or mosaic mutations. Gastrointestinal (GI) tract Lymphangioleiomyomatosis (LAM) is an extremely rare manifestation of TSC, with few reported cases. Herein, we aimed to determine the driver mutation, pathogenesis, and relationship of germline and somatic mutations of LAM through whole-genome sequencing (WGS) of the tumor and blood samples and whole transcriptome sequencing (WTS) analysis.

CASE PRESENTATION

A nine-year-old girl with a full-blown TSC presented with abdominal masses detected during a routine check-up. Resected intestinal masses were diagnosed as LAM by thorough pathological examination. Interestingly, the LAM presented a somatic TSC2 gene mutation in exon 24 (p.R905W, c.C2713T), and the patient had intron retention by a novel germline mutation in the intron region of TSC2 (chr16:2126489, C > G).

CONCLUSION

Our case suggests that intron retention by a single nucleotide intronic mutation of TSC2 is sufficient to develop severe manifestations of TSC, but the development of LAM requires an additional somatic oncogenic mutation of TSC2.