According to a study published in the Journal of Cellular and Molecular Medicine, the drug Lamivudine could palliate some symptoms of people with Down syndrome such as hyperactivity, poor memory, attention problems or speech difficulties.
The study, carried out by the Centre for Genomic Regulation (CRG) and the IrsiCaixa AIDS Research Institute, states that the antiretroviral, which is used in the treatment of Human Immunodeficiency Virus (HIV) infection, increased the cognitive ability in a mouse model.
This research has been carried out with a sample of Ts65Dn mice, which is the most studied animal model of Down syndrome to date. Segmentally trisomic Ts65Dn mice provide a postnatal model for Down syndrome. Cesium irradiation is used to produce a reciprocal translocation in its genome, which has some similarities to trisomy 21 in humans.
For four months, one group of a sample of these trisomic mice (all young adults) was treated with lamivudine dissolved in water and the other received only water. And subsequently, they were subjected to various behavioral experiments designed to test locomotor activity, recognition memory and anxiety.
“The study is very interesting because it has addressed a new possibility of treatment for Down syndrome,” says Casto Rivadulla, a neuroscientist at the Center for Advanced Scientific Research and professor of Physiology at the University of La Coruña. “It’s not going to cure Down syndrome, but it can alleviate some of the symptoms.”
“The first step has already been taken. Now we have to make the leap from the mouse to the patient”, adds Rivadulla. “There is still a lot of work to be done. But it has shown the possibility of reversing very complex cognitive alterations, such as object recognition memory, when animals are treated with the reverse transcriptase inhibitor.
“The first step has already been taken. Now we have to make the leap from the mouse to the patient”, adds Rivadulla. “There is still a lot of work to be done. But research has shown the possibility of reversing very complex cognitive alterations, such as object recognition memory, when animals are treated with the reverse transcriptase inhibitor.
It has also shown a new possible therapeutic target, not only for Down syndrome, but also for other neurodegenerative pathologies that must be explored, such as Alzheimer’s, thus opening new lines of work”, indicates the neuroscientist.
A genetic disorder
Down syndrome, also called trisomy 21, is a genetic disorder that includes certain congenital malformations, learning disabilities and facial features. A child with Down syndrome may also have heart, vision and hearing problems.
It is one of the most common congenital genetic malformations, affecting approximately 1 in 800 babies and 35,000 people in Spain. People with this syndrome also have an increased risk of Alzheimer’s disease because chromosome 21, which is triplicated, contains the genes for a protein that is especially relevant for this disease.
This protein, known as amyloid precursor protein (APP), has the ability to accumulate in the brain generating protein aggregates that cause altered brain function. The presentation of these protein aggregates is common in most adult individuals over 40 years with Down syndrome.
When Jérôme Lejeune, an eminent geneticist of the last century, discovered trisomy 21 as the genetic cause of Down syndrome, he aspired to find treatments that could improve those affected by the syndrome.
On many occasions, he expressed his radical opposition to his discovery being used to eliminate fetuses affected by this syndrome, through prenatal or preimplantation genetic diagnosis. Today, unfortunately, more than 90% of those affected are aborted.
The advance we are dealing with today is a step in the direction marked by Lejeune. However, the limitations of the present work, which uses mice in which a genetic translocation that partially reproduces trisomy in humans has been artificially induced, should be pointed out.
But the differences continue to be enormous, as well as the correct evaluation of the changes produced after the treatment, which means that we must be cautious in the weighted assessment of the expectations of this trial. New studies, on models closer to humans, will be necessary to confirm the advances that are now indicated.
Any progress in this direction should be applauded because it contributes to trying to improve the quality of life of those affected, instead of aborting them, which is what is currently being done mostly.
Cristina Castillo and Julio Tudela
Bioethics Observatory – Institute of Life Sciences
Catholic University of Valencia