In Seville, the parents of eight-year-old Darío have launched a campaign to fund research into a rare mitochondrial disease that affects only two children in Spain. After years of uncertainty and repeated warnings from doctors about their son's prognosis, the family is seeking new treatment options for the condition, identified as mitochondrial DNA depletion syndrome type 9, associated with the SUCLG1 gene.
The syndrome involves abnormally low levels of mitochondrial DNA, which can impair a cell’s ability to produce energy. This group of diseases is linked to mutations in nuclear genes that maintain mitochondrial DNA copy numbers, rather than mutations in mitochondrial DNA itself. Local coverage has described the condition as affecting about 20 people worldwide. Darío’s symptoms began before his first birthday, with loss of head control followed by progressive loss of motor function and complications including difficulty swallowing and respiratory problems. Many children with this diagnosis face a severe prognosis, including risks associated with metabolic acidosis. Darío has lived beyond the early childhood period described as typical in that account.
After receiving a diagnosis in 2025, the family established the association Un Guerrero llamado Darío to raise funds and connect with researchers. Their efforts brought them to the Centro Andaluz de Biología del Desarrollo at the Universidad Pablo de Olavide (UPO), where researcher and professor José Antonio Sánchez Alcázar leads a team working on mitochondrial diseases and potential therapeutic approaches through Proyecto MITOCURE. The research aims to investigate possible alternatives; it is not an established cure for Darío’s specific mutation. Current care for the syndrome remains supportive, focused on symptoms and individual complications.
Laboratory studies using Darío’s cells are assessing whether commercially available supplements might address cellular defects associated with his mutation. Any laboratory findings are a research step, not proof that a treatment will work in a patient. The family has committed €100,000 over two years to support the work. Their fundraising campaign has also been linked to community events in Tomares, including the XII Carrera Popular Solidaria Ciudad de Tomares, organized by the Ayuntamiento de Tomares and Club Maratón Tomares. Organizers expected hundreds of runners and support from around 20 companies and institutions. Proceeds were designated for the association and its work to improve quality of life and support mitochondrial-disease research.
Diario de Sevilla has covered Darío’s case, while elDiario.es reported on the Tomares race and its fundraising purpose. The event was presented as a way to raise awareness and support research, not as funding for an approved therapy. The family says it feels isolated from public institutions and points to the difficulties families can face when diagnoses are delayed. Darío’s mother, Ana Carrasco, is a physiotherapist active in patient advocacy groups. She has raised concerns about healthcare professionals’ training and the need for more geneticists in public hospitals.
Darío has a 94% motor disability, while his cognitive abilities remain strong. He communicates using eye-tracking technology on a tablet. The family is also in talks with a research group in San Sebastián about gene therapy, an approach that would require regulatory review before any clinical use. Reporting on the campaign has not established regulatory approval or a confirmed treatment for Darío’s specific SUCLG1 mutation.
Spain has more than 7,000 identified rare diseases, and patient associations often help families handle care while supporting research and awareness. For mitochondrial DNA depletion syndromes, the scientific challenge is to understand how disrupted mitochondrial DNA maintenance affects cellular energy production and whether potential approaches can safely improve patients’ outcomes. Darío’s campaign brings that research effort together with family advocacy and community fundraising as the search for a treatment continues.
