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Carmen was only three months old when, on Three Kings Day 2021, she was admitted to the hospital with seizures, nodding, heavy breathing and blinking. The prognosis was atrocious: “He has six months to live.” Javier Silva, his father, remembers the emptiness of the room, the vertigo, the pain that prevented him from thinking and moving. But Carmen has clung to life and has survived three years. Her desire has led her parents to not stop fighting, to deny the omen and look for a modicum of hope throughout the world. And they have found it in Ángel Carracedo, director of the Galician Public Foundation for Xenomics Medicine, and in the Center for Research in Molecular Medicine and Chronic Diseases (CIMUS). They have found out that the origin of the disease that keeps Carmen with a 94% disability is a strange mutation and they have opened up two treatment possibilities: genetic editing and messenger RNA. Carmen and millions of people whose lives have been cut short due to an error in the information on which life is built depend on these alternatives.
The little girl lives in Benalmádena (Málaga) with her parents, Javier, 51, and Laura Bergillos, 38. Since the first diagnosis, epileptic and developmental encephalopathy with malignant migratory focal seizures, known as “infant malignant epilepsy”, They have poured themselves into it. “We set up the hospital at home and I learned to be my daughter’s nurse,” recalls Laura, fresh from a stimulation therapy session that she replicates daily. The little girl’s maternal grandparents are part of the permanent care team.
Carmen cannot control her muscles and barely manages to keep her head up for a few seconds. Her arms and legs are those of her parents and grandparents and a stander, a device similar to a high chair that allows her to remain upright. She eats through a gastric button due to dysphagia (difficulty or absolute impossibility of swallowing) and she cannot speak either. But she sketches smiles that flood the house, a home full of light and color that exudes what, according to Javier, is the main treatment: “affection.”
With this medicine, two daily antiepileptics and a new ketogenic diet (high in fat, low in carbohydrates and moderate in proteins) complementary and temporary due to its long-term side effects, Carmen’s seizures have been reduced to one a day (“she arrived to suffer 50 every 24 hours,” recalls Laura) and shows timid functional progress. But the solution is more complex, attacking the original cause, the error in the genetic coding of GABRB3, which prevented normal development from the embryonic phase.
Carracedo is one of the most influential geneticists in the world, professor at the University of Santiago de Compostela (he is passionate about teaching) and co-director of the Networked Biomedical Research Center for Rare Diseases (Ciberer). When he learned Carmen’s story he did not hesitate to throw himself into the case. “It is a spectacular family in every sense: fighters and brave people who dedicate their lives to the girl,” he highlights.
“The mutation in Carmen’s GABRB3 gene makes it non-functional and generates a series of problems: not only epilepsy, but also hypotonia. [debilidad muscular], neurosis and neurodevelopment,” explains Carracedo. Only about 20,000 genes code for proteins, 1% of the total human genome. Many are genes for synapses, for neuronal connections, and this is one of them.
“Carmen’s mutation is unique, but there are other people with mutations in this gene. It is a rare, ultra-rare disease, if only the frequency in the population is analyzed, but together they account for 8% of all diseases. It is not trivial. There are many people who have absolutely similar problems with other genes,” adds Carracedo.
This is one of the keys to this race against the clock undertaken by everyone around the little girl. In Spain, according to the Spanish Federation of Rare Diseases (FEDER), three million people suffer from them (400 million in the world) and the diagnosis is delayed between four and 10 years. Juan Carrión, president of FEDER, estimates that “more than 70% have a genetic origin and two out of three appear in childhood.” Hence, the door that has been opened for Carmen in terms of the diagnosis protocol and possible treatment is also open for thousands of people.
But the strategy is complex. In a very basic way, a genetic therapy consists of identifying the gene and the mutation causing the problem, eliminating that defective part of the chain and replacing it with a correct part so that it works again thanks to the technique known as CRISPR, developed by Emmanuelle Charpentier and Jennifer Doudna based on the research of the Spanish microbiologist Francis Mojica and awarded the Nobel Prize in 2020. In the case of Carmen, it is much more complicated.
The team led by University of Santiago de Compostela (USC) researcher Catarina Allegue at the Center for Research in Molecular Medicine and Chronic Diseases analyzed the complete exome (part of the genome made up of exons, the coding parts of genes) to arrive at to GABRB3, whose mutation was already described as pathogenic.
Given the impossibility of reaching the precise point in Carmen’s brain, tissue or pluripotent stem cells from the blood are used, those with the capacity to form all the cells in the body. These show a map of the little girl’s neurons and, compared to control models, point out the specific mutation.
The same cells make it possible to reconstruct an organoid, a tissue similar to that of Carmen’s brain. “This gives us much more global information because we do not have the neurons separately, but rather we have all the groups that interact with each other,” explains Allegue.
This complex model has been fundamental because it has provided a key to one of the treatment strategies. “We found that, in the case of Carmen, the GABRB3 gene is expressed very little, both in the organoid and in the control organ. [el modelo de cómo debería ser], from the first stages of development. After 15, 30 or 45 days, very little or practically nothing is expressed. “We deduce that it is a gene that acts early in embryonic development, but then is no longer needed.”
In this way, the research hypothesis is that the damage in Carmen occurred at an initial stage and that, given the almost null expression of the gene after these primary phases of development, modifying GABRB3 could be useless. “Even if we send a CRISPR to try to repair that mutation, if that gene is no longer being expressed, if it is no longer producing proteins because it is no longer needed, we are not going to reverse anything,” summarizes the researcher.
The discovery forces us to rethink the strategy. The target is not only the original gene but also those that it should have influenced in the first embryonic phases. “Genes interact with each other in pathways and in them we can identify another gene on which we can act and that could be a potential therapeutic target,” details Allegue. To find out the mechanisms that must be modified, and based on the brain organoid, they have already begun a study of Carmen’s proteome, the complete set of proteins that generate the coding genes to overexpress those affected by the original GABRB3 dysfunction.
Another of the complexities of this unexplored scientific and vital adventure is how to bring the genetic modifications to the exact location of the brain. In this sense, they are testing in the organoid with lipid nanoparticles developed by a company that emerged from the USC and with adeno-associated compounds generated by a group from Navarra. This last vehicle is a virus specific to the target tissue (brain in Carmen’s case) that acts as a messenger to carry the repaired part and the tools to replace the damaged one. For each of the systems they already have candidates with promising results.
In parallel, the Galician team investigates the possibility of a treatment based on messenger RNA, which allowed the development of the vaccine against covid. RNA, from the genetic information in DNA, generates proteins that perform critical functions in the body. The objective is to design a ribonucleic acid with the precise instructions so that Carmen’s cells make the proteins she needs.
In this complex crusade, time is against us and resources are scarce. Genetic and RNA therapies are today the only solutions for Carmen and other similar diseases. Its treatment can establish, for the first time in the world, a guide with which to face pathologies of similar origin. There is no alternative and no time to waste. Media, financing and cases are needed that serve as a mirror for Carmen’s pathology and provide data to complete the investigations.
Laura has played a fundamental role in this regard. She has contacted half the world in search of similar cases and does not stop investigating any progress in this field on her own. He has established a social network of parents with similar problems and has become involved with Cure Gaba, an NGO created in the United States to promote research and study of diseases and effective treatments for genetic disorders that affect Gaba, the general term for the affected neurotransmitter. due to mutations.
From the activity of this entity has arisen the collaboration with a Danish group that already experiments with mice. Their results are decisive in accelerating the tests and approving Carmen’s therapy, which will not be ready for at least six months.
But the objective is firm. There is no rest for all parties involved, although no one can guarantee the results. It will be the first time that it is applied in a case like Carmen’s, but the results obtained will be useful not only for her, but for all those who suffer from the ailments of an error in genetic coding. “I am satisfied that she can hug me,” says Javier.
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