Investigating How Childhood Tumours and Congenital Disease Develop

Cancers and some congenital anomalies are caused by changes (mutations) in the genetic code (DNA) of cells. The use of Next Generation Sequencing (NGS) has enabled the study of the genetic changes that underpin these diseases, genome wide and at base pair resolution. A key question about the molecular pathogenesis of a range of childhood tumours and congenital anomalies that remains unanswered is the order in which the different mutations arise. To define the order in which mutations arise, the investigators will need to reconstruct the life history of individual tumours / anomalies. This can be achieved by segregating the major clone ('ancestral' cell) from sub-clones or by studying multiple areas from the same lesion. Although this approach allows timing of mutations to some degree, in childhood tumours and congenital lesions this approach is fundamentally limited by the inability to define embryonic mutations. The basis of the limitation is that the lesions in question is conventionally compared to the patient's germline (the genetic information they have from birth). In such a comparison embryonic mutations will be misclassified as either germline or somatic (acquired). To overcome this limitation one would have to compare the lesion to the parental germline. Thus, here this study proposes to perform the first NGS study of childhood tumours and congenital anomalies, focusing on defining the embryonic pathogenesis. A unique feature of this study will be that lesions will be compared to the parental germline to define embryonic mutations. A focus of the analysis will be to define order in which mutations arise.