title: Ultra deep sequencing detects a low rate of mosaic mutations in tuberous sclerosis complex.
abstract: Tuberous sclerosis complex (TSC) is an autosomal dominant neurocutaneous syndrome caused by mutations in TSC1 and TSC2. However, 10-15% TSC patients have no mutation identified with conventional molecular diagnostic studies. We used the ultra-deep pyrosequencing technique of 454 Sequencing to search for mosaicism in 38 TSC patients who had no TSC1 or TSC2 mutation identified by conventional methods. Two TSC2 mutations were identified, each at 5.3% read frequency in different patients, consistent with mosaicism. Both mosaic mutations were confirmed by several methods. Five of 38 samples were found to have heterozygous non-mosaic mutations, which had been missed in earlier analyses. Several other possible low-frequency mosaic mutations were identified by deep sequencing, but were discarded as artifacts by secondary studies. The low frequency of detection of mosaic mutations, two (6%) of 33, suggests that the majority of TSC patients who have no mutation identified are not due to mosaicism, but rather other causes, which remain to be determined. These findings indicate the ability of deep sequencing, coupled with secondary confirmatory analyses, to detect low-frequency mosaic mutations.
authors.affiliation: Translational Medicine Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Qin
authors.forename: Piotr
authors.initials: P
authors.lastname: Kozlowski
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Taillon
authors.forename: Pascal
authors.initials: P
authors.lastname: Bouffard
authors.forename: Alison J
authors.initials: AJ
authors.lastname: Holmes
authors.forename: Pasi
authors.initials: P
authors.lastname: Janne
authors.forename: Susana
authors.initials: S
authors.lastname: Camposano
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Thiele
authors.forename: David
authors.initials: D
authors.lastname: Franz
authors.forename: David J
authors.initials: DJ
authors.lastname: Kwiatkowski
mesh_terms: D002851:Chromatography, High Pressure Liquid; D005838:Genotype; D006801:Humans; D013058:Mass Spectrometry; D009030:Mosaicism; D009154:Mutation; D010641:Phenotype; D016133:Polymerase Chain Reaction; D017421:Sequence Analysis / Q000379:methods*; D014402:Tuberous Sclerosis / Q000235:genetics*; D000077004:Tuberous Sclerosis Complex 1 Protein; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins / Q000235:genetics*
chemical_list: C000624650:TSC1 protein, human; C000624653:TSC2 protein, human; D000077004:Tuberous Sclerosis Complex 1 Protein; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins