Investigations into the genetic causes of liver disease using molecular genetic technologies

DNA sequencing technologies have developed quickly in the last decade, and new methodologies have moved into clinical practice. These can been used to investigate genetic causes of neonatal cholestasis. Neonatal cholestasis can be life-threatening and has a varied etiology. In chapter 3, a targeted next generation sequencing (tNGS) assay was designed and assessed for suitability for detection of known mutations in genes associated with cholestasis. In chapter 4, this was used to screen over 200 infants presenting with liver disease for mutations in the (ATP8B1), (ABCB11), (ABCB4), (NPC1), (NPC2) and (SLC25A13) genes. Diagnoses were made in 9% and single heterozygous mutations were in 9% of cases. In chapter 5, patients suspected of PFIC-related disease werE tested for mutations in the (ATP8B1), (ABCB11) and (ABCB4) genes. This study uncovered 27 novel sequence variants, including 22 in UK patients, expanding the known mutation spectrum of these disorders. In chapter 6, patients suspected of NPC and were tested for mutations in (NPC1) and (NPC2), or (SLC25A13), respectively. These studies have identified 134 novel NPC mutations and 4 novel CD mutations. Current and future DNA sequencing methods are discussed, as are new diagnostic strategies for genetically heterogeneous conditions like infantile liver disease