Defects in nuclear DNA account for approximately 75-80% of paediatric Mitochondrial Disease, but it is estimated that only a tiny proportion of these cases actually have a confirmed genetic diagnosis.
There are believed to be over 1000 nuclear genes involved in mitochondrial function, but to date only around 300 of these have been linked to disease, making genetic diagnosis of nuclear DNA disease a huge challenge.
The NHS genetic testing service currently only screens for about 4% of these known genes which leaves a very high proportion of families with no answers. Genetic diagnosis can be invaluable when assessing risk to other family members, for future family planning and in some cases, it can even help direct treatment.
Exome sequencing is a technique which can look at 1000's of genes at the same time, and is much more efficient than standard single gene testing. Unfortunately there is currently no NHS provision for exome sequencing.
In 2012, Lily and the team at Guy's & St Thomas' set about trying to change this. They planned and developed a detailed genetic testing pathway and with the support of Newcastle University they started recruiting families in early 2014.
The aim of our Lily exome sequencing project would be to sequence 100 patients with nuclear mitochondrial defects, giving families a genetic diagnosis for their Mitochondrial Disease and hopefully, in the process, discover new disease causing genes to help improve the understanding of this condition.
This ambitious project would accept samples from all over the country via the 3 major centres of excellence in Mitochondrial Disease (Newcastle, Oxford and London).
You can read more about our exome sequencing project below:
To date we have screened 202 families and provided definite, or highly likely answers in 73% of these cases.
Before our study, families often had to wait years to get a genetic diagnosis for their child, and even then, the success rate was low, with maybe only 20% receiving the genetic diagnosis they had hoped for.
Unfortunately, a minority of our families still do not receive a genetic diagnosis from initial screening, so further investigation work is required. Lily funds 2 specialist mitochondrial disease researchers at Newcastle to undertake follow up work on these cases, to ensure all our families (even those with very rare forms of disease) have the best opportunity to get a genetic diagnosis.
Lily funding has already identified 34 novel mutations linked to mitochondrial function which were not previously known to cause disease, so our work is greatly advancing the understanding of Mitochondrial Disease, as well as helping give answers to individual families.
Our project is the first country wide collaboration of its kind for Mitochondrial Disease diagnostics in the UK, and we will continue to fund this valuable testing for families, until an equivalent NHS service is in place.
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