00:00 [Music]
00:03 Mitochondrial diseases cover a wide range of conditions caused by genetic mutations.
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00:11 In the UK alone, they affect thousands.
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00:17 Mitochondria are the powerhouses of the cell.
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00:21 They use a process called oxidative phosphorylation to generate energy.
00:25 [Music]
00:27 But a mitochondrion is a complex piece of machinery, and a lot can go wrong.
00:32 It takes around 1,500 proteins for mitochondria to function,
00:37 and problems with many of these can lead to disease.
00:40 [Music]
00:43 The cell's nuclear DNA creates all but 13 of these proteins.
00:48 The rest are coded for by the DNA in the mitochondria themselves.
00:53 And mutations in either can cause problems.
00:56 [Music]
00:57 A cell has just one nucleus and many mitochondria.
01:02 All the cell's mitochondria contain their own DNA.
01:06 If a mutation affects mitochondrial DNA, some might be healthy, others defective.
01:13 And different cells can have different numbers of defective mitochondria inside them.
01:19 That means that some cells may be less affected than others.
01:22 [Music]
01:24 The diseases caused by damaged mitochondria can also be varied.
01:29 They can affect any organ or tissue, and they can appear at different times throughout life.
01:34 [Music]
01:39 For example, Leigh syndrome is the most common type to develop in childhood.
01:44 It can affect patients in a number of ways, including loss of skills,
01:48 epilepsy, and problems with muscle function.
01:52 Mutations in over 75 genes in both nuclear and mitochondrial DNA can lead to this syndrome.
02:00 So what can be done to tackle mitochondrial diseases like Leigh syndrome?
02:05 Treating patients is difficult, but in some cases the disease can be stopped before it's passed on.
02:13 Mitochondria are inherited from their mother.
02:17 If the mutation is in the mitochondrial DNA, this inheritance can be blocked.
02:24 One approach is to combine the nuclear DNA from an affected egg cell
02:28 with healthy mitochondria from another woman.
02:32 The embryo would then have nuclear DNA from the original mother and father,
02:37 and mitochondrial DNA from the egg cell donor.
02:41 This has led some to call such potential infants "three-parent babies."
02:47 This technique is still very new, but it has recently been approved in the UK.
02:53 It may be a controversial approach,
02:56 but techniques like these could finally help combat these devastating diseases.
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