Molecular biology is a merger between biochemistry and genetics that undertakes the study of the molecular fundamentals of metabolism of the genetic material, i.e., replication, the transcription and translation and its manipulation for the benefit of life. Molecular biology is the molecular three-dimensional structural studying approach of biology as reflected on genesis and function to search below the large-scale manifestations of classical biology. The recent merge of molecular biology and computer science developed bioinformatics and computational biology. The study of gene structure and function, i.e., molecular genetics, is amongst the most prominent sub-field of molecular biology. This book highlights the rationale behind most of the related diseases afflicting the nuclear and the mitochondrial genetic systems for specific prevention and/or intervention.