Projects

Human Genome – size, composition and human disease
The human genome can be thought of as a very complex recipe book, that contains the complete set of genetic instructions that define our biological makeup. The human genome contains roughly 20,000–21,000 protein-coding genes (‘recipes’), along with vast regulatory regions that help control how and when genes are expressed. The entire genome contains about 3 billion DNA base pairs (‘letters’), equivalent to about 1000 copies of War and Peace. It is divided into 23 pairs of chromosomes (‘chapters’) and despite its immense complexity, the entire genome is written with four letters only: A, T, G and C.
A ‘typo’ in the genome – insertion, deletion or substitution of even a single letter – can mean the difference between a healthy and a sick child!

Types of Gene Therapy

Gene therapy can be broadly divided into in vivo and ex vivo approaches.
In vivo (‘inside a living organism’) gene therapy delivers genetic material directly into a patient’s tissues – often using viral vectors – allowing cells to be modified inside the body.

Ex vivo (‘outside a living organism’) gene therapy involves removing patient cells, genetically modifying them in the laboratory, and then re-introducing them to provide a therapeutic effect.

Based on the mechanism of action, gene therapies can be divided into subsequent strategies:

• Gene augmentation (often referred to as ‘gene addition’) – when a new copy of the gene coding region is delivered to the target cell
• Gene silencing – when an endogenous gene is inactivated, or ‘turned off’
• Gene editing – when specific changes (insertions, deletions or substitutions) are introduced to the endogenous genetic sequence

Each strategy is designed to correct, replace, or modulate faulty genetic pathways, with the aim to

Vector based gene therapy

Vector-based gene therapies use engineered delivery vehicles – most commonly viral vectors – to transport therapeutic genetic material into target cells. These vectors are designed to efficiently enter cells, protect the genetic payload, and enable precise, long-lasting expression of the therapeutic gene. By tailoring vector properties such as tropism, payload capacity, and immunogenicity, vector-based approaches can be optimized for specific tissues, including the central nervous system.

Currently, viral vectors derived from non-pathogenic (‘not causing human disease’) adeno-associated virus (AAV) are the most commonly used vectors for in vivo gene therapies, including those targeting the brain, eye, liver and other clinically relevant targets. As of end of 2025, there are seven approved gene therapies utilising AAV vectors to deliver the therapeutic cargo to the target cells, with AAV2-based Luxturna® (treatment for a genetic type of blindness) and AAV9-based Zolgensma® (treatment for Spinal Muscular Atrophy, SMA) being the prominent exemplars of the impact AAV-based gene therapies can have on the lives of the patients and their families.

Promise of gene therapy

Gene therapy offers significant promise for rare genetic paediatric conditions by addressing the root cause of disease rather than managing symptoms. With the ability to deliver or correct genes in affected tissues early in life, gene therapy has the potential to halt or even reverse progressive disorders that previously had no effective treatment. As vector technologies and delivery methods continue to advance, these therapies offer hope for durable, life-changing outcomes in children with devastating inherited diseases.