Exploring_the_landscape_of_somatic_mutations_in_normal_tissue_GI_TPS___WGS

The aim of this project is to investigate somatic mutations, including rates of mutations and signatures, and clonal dynamics in normal (non-cancerous) human tissues from the gastrointestinal tract. The project will involve the study of normal tissues from healthy individuals and those with specific candidate diseases. We are utilising laser capture microscopy to identify and isolate specific cell populations which are then subjected to whole genome sequencing to estimate mutational burdens and begin to understand clonal structures across the normal tissues.

Type: Other
Archiver: European Genome-Phenome Archive (EGA)

2 Datasets

Click on a Dataset ID in the table below to learn more, and to find out who to contact about access to these data

Dataset ID	Description	Technology	Samples
EGAD00001008092	Lynch Syndrome (LS) is an autosomal dominant disease conferring a high risk of colorectal cancer due to germline heterozygous mutations in a DNA mismatch repair (MMR) gene. Although cancers in LS patients show elevated somatic mutation burdens, information on mutation rates in normal tissues and understanding of the trajectory from normal to cancer cell is limited. Here we whole-genome sequenced 152 crypts from normal and neoplastic epithelial tissues from LS patients. In normal tissues the repertoire of mutational processes and mutation rates were similar to those found in wild type individuals. A morphologically normal colonic crypt with an increased mutation burden and mutational signatures consistent with MMR deficiency was identified, which may represent a very early stage of LS pathogenesis. Phylogenetic tress of tumour crypts indicated that the most recent ancestor cell of each tumour was already MMR deficient and had experienced multiple clonal evolution cycles. This study demonstrates the genomic stability of epithelial cells with heterozygous germline MMR gene mutations and highlights important differences in the pathogenesis of LS from other colorectal cancer predisposition syndromes.	Illumina NovaSeq 6000	161
EGAD00001008764	The single base substitution mutational signatures SBS2 and SBS13, likely caused by APOBEC cytosine deaminases, are common in many human cancer types. However, the stimulus activating APOBEC mutagenesis is unknown and understanding of when it occurs in the progression from normal to cancer cell is limited. Here, as part of a wider survey of human tissues, we whole genome sequenced 342 microdissected normal epithelial crypts from the small intestines of 39 individuals. SBS2/13 mutations were present in 17% normal small intestine crypts and were likely due to APOBEC3A activity. Localised clusters of SBS2/13 mutations (kataegis) were also commonly found. APOBEC mutation burdens were variable between individuals and between crypts from the same individual. Crypts with SBS2/13 often had immediate crypt neighbours without SBS2/13, suggesting that the underlying cause of SBS2/13 is cell-intrinsic rather than a widely distributed microenvironmental exposure, or needs to be permitted by cell-intrinsic conditions. APOBEC mutagenesis occurred throughout the human lifespan, including in young children, and was episodic with a small number of episodes occurring during the life history of a single cell. The results indicate that APOBEC mutagenesis is more common in the small intestine epithelium than in many other cell types, and is an episodic process in vivo initiated or permitted by cell intrinsic factors.	HiSeq X Ten Illumina NovaSeq 6000	408

Exploring_the_landscape_of_somatic_mutations_in_normal_tissue___GI___TPS___WGS

Exploring_the_landscape_of_somatic_mutations_in_normal_tissue_GI_TPS___WGS