The Dixons are in the early stages of their rare disease journey. After whole genome sequencing, their two children were recently found to have the same ultra-rare gene mutation. Turning their grief into action, they are driving research through their charity, Cure DHDDS, in the hope of finding a treatment

By Mel Dixon

A genetic diagnosis

28 November is a day we will always remember. After 14 months of waiting, we finally got the call from our geneticist telling us that two of our beautiful children had a DHDDS genetic mutation, a single spelling mistake in their DNA.

This mutation, they went, on was ultra-rare and seemed to have both neurodevelopmental and, in many cases, neurodegenerative consequences.

Our two children had had symptoms such as mild learning difficulties, reduced balance dyspraxia and tremor since birth. Most people with these mutations also have seizures. Treatment we were told would be symptomatic, and understanding of this disease was in its infancy, as this gene was only decided to be disease-causing (pathogenic) in 2021. At the time there were only 59 confirmed cases worldwide.

We were told that as our children’s mutation is so rare, we will need to help find the cure or treatment. Not the words we expected to hear, but words I now realise are familiar to many of the rare disease community. This is where our rare disease journey really began.

Cure DHDDS

Since February we have grown our DHDDS community of patients and researchers. We have founded a charity—Cure DHDDS—and built a website. We have contacted every scientist that has ever written a paper on DHDDS with neurological symptoms. The silver lining here being that this task was not too onerous as the gene was only recently discovered to be pathogenic. However, this also confirmed just how few scientists knew about us. Those that did get back to us, though, offered us kindness and hope.

Our children’s condition causes a metabolic disorder, which is believed to sit on the intersection of lysosomal storage diseases and congenital disorders of glycosylation (or CDGs for short). As knowledge about our gene is still in its infancy, scientists are still deciding and disagreeing on how to categorise us. We have started to build and bring together a robust and international scientific advisory board, who have shared their theories as to a possible cause of degeneration in DHDDS patients.

Armed with this information our scientific team has shared their expertise with American biotec Perlara, who will soon start working on our mutations in their yeast models, with the hope of expediting treatment screening through their accelerated programmes. We have also found out that CHU Sainte-Justine research centre in Canada is studying our mutation, and is ready to start screening for treatments in their models if we can help with funding.

The promise of RNA (ribonucleic acid ) or ASO (antisense oligonucleotides) therapies dangles tantalisingly close but as ours is a newly found disease, and this is a young industry, it is currently heartbreakingly out of reach.

When you are dealing with a neurodegenerative disorder, time is of the essence, so we are doing all we can to speed up processes, which obviously comes at a cost. When not speaking with scientists or other patients we are busy fundraising in the hope of initially raising money for a suitable repurposed drug.

Turning grief into action

I was—and it turns out quite rightly—terrified of what whole genome sequencing would tell us. But our children’s mutation has given us opportunities, despite it being newly discovered. We are no longer looking at trialling medications to fix symptoms as they arise, but looking at medications that treat the cause.

 We know that we are still in the early stages of our journey but in turning our grief at diagnosis into action we can help drive research. We are driven in a way that I could never imagine. We need to be able to look our children in the eye knowing that we have done everything within our power to help them in their battle against this rare disease. And we firmly believe we can have a positive impact not just on our children’s future but for all those suffering from these mutations.

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