Recent years have seen rapid progress in biological treatments for genetic diseases, as well as conditions like type 1 diabetes that lack an obvious genetic component. The authors sought to explain why this progress has emerged at this particular moment. The best way to illustrate this is by showcasing a wide range of therapies targeting diverse diseases. This progress has been driven by technological advances in genetically modified CAR-T and CAR-NK cells (e.g., using CRISPR or transgenes), which have led to significant improvements in cancer therapy. A key trend now is the emergence of “off-the-shelf” approaches aimed at generating cellular therapies compatible with a range of recipients by mitigating alloreactivity and immune rejection. Different diseases impose distinct biological and logistical limitations; thus, treatment of each patient requires an appropriate strategy. Emerging advances include the modification of therapeutic cells, either ex vivo or in vivo. Current options for transgene delivery mainly comprise lipid nanoparticles (LNPs), adeno-associated virus (AAV) vectors, and lentiviral vectors. Researchers also focus on selecting suitable promoters for specific expression in selected cell types. Altogether, these advances have led to remarkable progress in treating various diseases in recent years. This publication discusses the development of biological therapies, with particular emphasis on cell and gene therapies, illustrated by viable examples across various disorders. It covers implemented solutions for several types of cancer, as well as selected hereditary diseases and syndromes, including Huntington’s disease, carbamoyl phosphate synthetase 1 (CPS1) deficiency, hemiplegia, epidermolysis bullosa, chronic granulomatous disease, and congenital deafness. Emerging applications in heart diseases and diabetes are also summarized, along with therapeutic strategies involving tRNA gene editing. Although numerous strategies exist, only the most representative, practical, and up-to-date examples are emphasized.