The use of new genetic technologies in patient approach: a mini-review of the literature
Mini-Review, 140 - 146Tag this article
The clarification of the molecular basis of diseases allows the discovery of new treatment strategies, both in terms of chirurgical, pharmacological, biological, cellular, and genetic therapies. Thus, good use of genetic diagnosis can positively impact the life of the patient and his relatives. DNA sequencing technologies, in use since the early 1970s, have brought about a dramatic change on the scenario of genetic diseases thanks to the advent of Next Generation Sequencing (NGS) over the past 15 years. The application of these new sequencing strategies by a system-wide, unbiased approach allows to identify all DNA variants in the genome simultaneously, thus marking the transition from the Mendelian era to the genomic era. The sequencing of the whole set of protein-coding genes (Whole Exome Sequencing, WES), formally demonstrated that single gene disorders are the exception more than the rule. Indeed, the same embryogenetic defect is frequently associated with variants in many different genes, each sufficient to prevent proper embryonic development. The WES approach also highlighted examples of pleiotropy, showing that variants in the same gene can be associated with apparently unrelated diseases, thus increasing our understanding of the underlying pathogenetic processes, and implicitly, their treatment and prevention. Furthermore, the WES investigation is also highlighting the role of modifier genes even in diseases whose molecular bases were considered definitively elucidated, and both WES and WGS (Whole Genome Sequencing, including non-coding sequences) are clarifying the role of common variants, which in association with rare allelic variants, partly explain the diseases characterized by incomplete penetrance. Equally important for understanding the molecular basis of the disease are the emerging studies related to highresolution CpG profiling based on NGS. These investigations allow the fine mapping of those epigenetic signals that are determinant in the expression / silencing of tissue- specific genes, not to mention the numerous driver and passenger genes crucial to cancer deveolopment.
KEY WORDS: next-generation sequencing; mendelian disorders; variable expressivity; genetic heterogeneity.