Batten disease is a genetic illness caused by brain cells being unable to probably dispose of waste products. While the disease is rare, children affected by it often develop seizures and blindness and will typically die before their teens. Recently, a group of scientists led by Timothy Yu at Boston Children’s Hospital, attempted to treat a young girl named Mila with this disease. They took a sample of Mila’s blood and read the genetic code stored within her cells. From this information, they were able to determine where the genetic mistake causing the disease was located. The researchers then designed a drug made out of a piece of DNA called an antisense nucleotide. Antisense nucleotides are pieces of DNA that prevent faulty genetic material from actually being used inside a cell, ideally rendering the faulty genetic material harmless.

At Boston Children’s hospital, Mila’s medical team injected this medicine, which they called Milasen, into the fluid surrounding her spinal cord. Small but increasing doses were first given every two weeks, followed by steady maintenance doses every three months. The drug did not appear to cause any significant side effects for Mila. The treatment did succeed in decreasing the number of seizures Mila experienced by 63%. The length of each seizure on average also decreased from almost two minutes to less than one minute. Combined, this meant that she went from experiencing a seizure for almost 4% of the average day, to only 0.6%. Tests of Mila’s development showed that she largely maintained her skill level in a range of social, communication, and personal developmental metrics under the medication regime, although she had been losing these skills rapidly beforehand.

Although Milasen improved Mila’s quality of life, brain imaging shows that it did not stop the loss of brain cells associated with the progression of the disease. It is hard to predict the future course of Mila’s disease. Also, because the drug is based on Mila’s own genetic code, it can’t be applied to other patients with the same disease. The general approach of designing an antisense nucleotide to treat genetic diseases may be generalizable, however. The authors do warn that these kinds of trials are not without risk, since the drug can only be tested on animals and the person for whom it was designed. Therefore, the authors advise that this approach be limited to patients with extremely serious diseases.

Managing Correspondent: Emily Kerr

Press Article: Drug tailored to one girl with brain disease paves way for similar customized treatments

Scientific Article: Patient-Customized Oligonucleotide Therapy for a Rare Genetic Disease

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