Andorra's Sole CTNNB1 Syndrome Patient Seeks Experimental Treatment

Guillem Mallandrich Feixas is the only person diagnosed with CTNNB1 syndrome in Andorra, a rare genetic disorder with no known cure. His family is pushing for greater support and research funding while planning a trip to Slovenia for an experimental treatment.

Born without apparent issues, Guillem's early months seemed normal. At five months, a routine paediatric check revealed he could not yet hold his head up. His parents, Maria Feixas and Jaume Mallandrich, initially dismissed it, noting their older daughter Ares had developed motor skills slowly. By six months, doctors urged further tests, launching years of medical investigations across Andorra and Catalonia.

Initial assessments at Andorra's Nostra Senyora de Meritxell Hospital pointed to hypotonia in his upper trunk, prompting twice-weekly physiotherapy sessions. The Child Development Unit recommended a second opinion at Barcelona's Sant Joan de Déu Hospital, a neuropaediatrics reference centre. Tests—including blood work, MRI scans, visual studies and specialist exams—came back normal for months, but suspicions of a genetic cause led to a full exome sequencing analysis.

The definitive diagnosis arrived nearly a year later: CTNNB1 syndrome, identified in 2012. Caused by a spontaneous mutation on chromosome 3 affecting the beta-catenin protein, it disrupts neurological development and shortens life expectancy. Globally, only 450 to 500 cases exist, with 40 in Spain, 10 in Catalonia and this sole case in Andorra.

The news brought mixed emotions for the parents. They finally had a name for Guillem's condition but entered the challenging world of rare diseases. Now, he requires constant assistance for basic daily activities that peers manage independently. He cannot sit or move normally and needs school support to join activities. His nursery flagged the need for more resources, leading to the Impuls programme run by the Fundació Privada Nostra Senyora de Meritxell, which provides essential therapeutic and educational aid for early stimulation.

The family praises Andorra's system as relatively effective compared to elsewhere, but stresses the path to help can be arduous. "A child with a rare disease cannot wait months or years for support—the development window does not pause," they said. They often know more about the condition than many healthcare professionals, as no specialists exist for it.

Amid the daily challenges, hope lies in research. The family aims to travel to Slovenia in April for an early-stage experimental treatment targeting CTNNB1 children, which could improve Guillem's quality of life and potentially lead to a cure. They now seek financial and institutional backing to pursue every opportunity for their son.