A family in Seville is funding research for their son Darío, one of two children in Spain with a rare mitochondrial disease. With no public support, they turn to science and society for hope.
In Seville, the parents of eight-year-old Darío have launched an urgent 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 now at the center of a unique effort to find new treatment options for the condition, known as Mitochondrial DNA Depletion Syndrome type 9 (SUCLG1 gene).
Darío's illness, which has no cure and is documented in just 20 cases worldwide, causes rapid degeneration. Symptoms began before his first birthday, with loss of head control, followed by progressive loss of motor functions and severe complications such as difficulty swallowing and respiratory issues. Most children with this diagnosis do not survive beyond two years due to metabolic acidosis, but Darío has defied expectations.
After finally receiving a diagnosis in 2025, the family realized that no treatment or research existed for this specific mutation in Spain. Refusing to accept inaction, they established the association Un guerrero llamado Darío to raise funds and connect with scientists willing to take on the challenge. Their search led them to the Centro Andaluz de Biología del Desarrollo at the Universidad Pablo de Olavide (UPO) in Seville, where a team led by Professor José Antonio Sánchez Alcázar has been working on precision medicine for rare genetic diseases since 2014.
The UPO team is now conducting laboratory studies using Darío's own cells to test commercially available supplements that might correct the cellular defects caused by his mutation. Encouraged by positive results from a related clinical trial involving 22 children at Hospital Virgen Macarena, the researchers began working with Darío and another affected child, Quim from Menorca, in January. The association has committed to providing €100,000 over two years to support this research, ensuring that lack of funding does not delay progress.
Despite these advances, the family reports feeling isolated from public institutions. They highlight the lack of government investment in rare disease research and the bureaucratic hurdles families face, especially when diagnoses are delayed. The mother, Ana Carrasco, who is also a physiotherapist and active in patient advocacy groups, points to insufficient training among healthcare professionals and the need for more geneticists in public hospitals.
If the laboratory improvements in Darío's cellular energy can be replicated in his body, his quality of life could improve significantly. Although he has a 94% motor disability, his cognitive abilities remain strong, and he communicates using eye-tracking technology on a tablet. The family is also in talks with a research group in San Sebastián exploring gene therapy, but such work would require regulatory approval in Spain.
According to available data, Spain has over 7,000 identified rare diseases, but most receive little or no dedicated research funding. Patient associations often fill the gap, driving initiatives and supporting families. The case of Darío underscores the challenges faced by those affected by ultra-rare conditions and the critical role of community support and scientific collaboration in advancing potential treatments.
