Researchers from the University of Exeter and the Royal Devon University Healthcare NHS Foundation Trust followed up on the impact of those diagnosed as part of the DDD study, a collaboration between the NHS and the Wellcome Sanger Institute. This large-scale project, which began over a decade ago, has led to life-changing diagnoses for over 5,500 families across the UK and Ireland and the discovery of 60 new genetic conditions.

The findings, published in Genetics in Medicine Open (14 October), reveal that over a thousand of those diagnosed were able to alter their treatment or undergo further medical testing based on their genetic findings, significantly improving their quality of life.

The Deciphering Developmental Disorders (DDD) study included 13,500 families, recruited from 24 regional genetics services across the UK and Ireland. All the families had children with a severe developmental disorder, which was undiagnosed despite prior testing and likely to be caused by a single genetic change. The Wellcome Sanger Institute sequenced all the genes in the children’s’ and parents’ genomes to look for answers, a search which is still ongoing.

In this new study, researchers analysed outcomes for 4,237 of the families who received a genetic diagnosis, finding 76 per cent (3,214 people) were given condition-specific information or support. A further 28 per cent (1,183 people) of people were able to change treatment or get further medical testing because of their diagnosis. Over 20 per cent (880 people) joined patient support groups, such as Unique to connect with others facing similar challenges.

Additionally, 143 people were able to start, stop or adjust specific therapies, which can have a major impact on quality of life, and even be lifesaving. Researchers expect this number to grow, as new genetic therapies continue to develop.

Caroline Wright, Professor of Genomic Medicine at the University of Exeter and author of the study, said: “Around 1 in 17 people are affected by a rare genetic disorder, the majority of whom are children, and making the right diagnosis is critical to getting the best treatment and care. We now have the technology to make a genetic diagnosis swiftly in around 50 per cent of people affected by rare conditions — but the challenge can be having enough data to understand each condition, as they’re so rare individually. Our study is part of global research giving answers that families need so desperately, to ensure they are on the best management pathway for them. It’s so gratifying to hear stories … where a genetic diagnosis really is life-changing. Our research will lead to more families being diagnosed as early as possible in future.”

Helen Firth, Professor of Clinical Genomics at the University of Cambridge, Honorary Faculty Member at Wellcome Sanger Institute and author of the study, said: “Genomic testing is enabling far more people to receive a molecular genetic diagnosis of their rare disorder. These diagnoses are a launch pad to more tailored management and treatment based on the specific genetic diagnosis. This paper studied the impact of a genetic diagnosis for patients diagnosed by the DDD study. It provides a template for improving care and support following a genetic diagnosis.”

Professor Matthew Hurles, Director of the Wellcome Sanger Institute and lead of the DDD study, said: “It is both deeply gratifying and sobering to understand the impact that our research has had on thousands of DDD families. We can feel proud that through the integration of the nationwide scale of the NHS and being on the cutting edge of new genomic technologies, the UK has been pioneering in the application of new genomic technologies to diagnose rare disorders. However, this study also highlights how much more work is needed to find treatments for the majority of rare disorders. Nevertheless, it is clear that even without a disease-specific therapy being available, participating families can benefit substantially from having a definitive molecular diagnosis for their child’s condition.”

Sarah Wynn, Chief Executive Officer of Unique, which supports families affected by rare genetic disorders and has been involved in the DDD study from the outset, said: “This study has provided so many families with an explanation for their child’s developmental delay, and has also identified numerous genes involved in causing their conditions. Many of these families have waited a long time to get this answer, and they are now able to better understand their child and their needs, enabling access to the appropriate care and support. Families are also understandably desperate for information about how their child may be affected now, and in the future, but for rare conditions such as these, there is often a complete lack of information. A vital output of the DDD project has been the collaboration with Unique to produce much-needed family-friendly patient literature, which benefits not only the project participants, but all those subsequently diagnosed.”

Andrew Gwynne, UK Minister for Public Health and Prevention, said: “Innovative research is vital to increasing our understanding of all illnesses, and saving lives, just like Jaydi’s. Helping people get a final diagnosis faster is one of the key priorities in the UK Rare Diseases Framework and we are continuously committed to making improvements to the health and care system for people living with rare conditions.”