Mitochondrial diseases explained

Evening Standard

Mitochondrial diseases are a group of disorders caused by genetic mutations.  In this animation, Nature Video finds out how these diseases arise, and how new techniques can stop them being passed on from mother to child.

Transcript

00:00 [Music]

00:03 Mitochondrial diseases cover a wide range of conditions caused by genetic mutations.

00:09 [Music]

00:11 In the UK alone, they affect thousands.

00:14 [Music]

00:17 Mitochondria are the powerhouses of the cell.

00:20 [Music]

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.

03:02 [Music]

03:22 [Music]

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