What happens in Batten disease, exactly?

What is it?

Batten disease is a very rare, fatal, hereditary neurodegenerative disorder. The symptoms begin in childhood, and they include vision problems, seizures, changes in personality and behavior, and problems with learning. Over time the symptoms worsen, and eventually the patient becomes blind, bedridden, demented, and dies. While there is a less severe form of the disorder that onsets in adulthood and progresses slower, the vast majority of affected children  die before the age of 12.

Batten disease affects about 2 to 4 children born alive in 100 000.

What causes it?

Batten disease is caused by a genetic mutation. The disorder is inherited recessively, which means that you need a copy of the faulty gene from both your mother and your father. This means that healthy parents could both carry the mutation, and each of their children would have a roughly 25% chance of getting the disorder, a 50% chance of carrying one faulty gene but not being affected themselves, and a 25% chance of having two healthy genes.

What happens during it?

Lysosomes are little vesicles inside our cells that break down things like useless or faulty cell organelles or molecules. If something they can’t process ends inside them, they store it. This is what happens in Batten disease – substances called lipopigments, aggregates made up of fats and proteins, start accumulating inside the lysosomes. This starts slowly affecting the functioning of the cell. This happens in many parts of the body but is particularly harmful to the nervous system. There are many genetic mutations that can lead to Batten disease and in many of them the purpose of the faulty protein is not known. In those where it is known, however, the protein plays a part in breaking other proteins down. This is probably why the disorder is recessive – even if a person has one faulty gene, they still have one healthy one that produces the protein in question. Appropriate breaking down still takes place, even if it’s less efficient than in completely healthy people. If a person has two faulty genes, none of the protein is produced. Whatever the protein is supposed to break down stays stored inside the lysosomes because there simply isn’t anything around to do the job.

How can it be treated?

Unfortunately there is no cure for Batten disease. Treatment focuses on alleviating the symptoms of the affected, and because each case is presented as a slightly different set of symptoms, the treatment is also altered individually. Even though the people who suffer from Batten disease and the people who love them are currently forced to face a horrible tragedy, the development of gene technology gives a reason to hope that some day we may find an effective cure.

 

 

Sources: http://www.ninds.nih.gov/disorders/batten/detail_batten.htm, https://en.wikipedia.org/wiki/Batten_disease

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