When Lucía goes down to the park to play, the other children look at her because she doesn't behave like them. Jose, her father, explains helplessly that they had to change her school because her classmates bullied her without the teachers or families doing anything to prevent it. He is also a teacher and understands that the other children look at her when she plays; they are young and have surely never seen a girl like Lucía, who has a very rare disease that only affects 30 children worldwide. However, he does not understand the adults' lack of empathy and wonders why no one protected her at that school.

Misha was born on July 3, 2025. Six days later, on the 9th, his mother, Madona, received a call from Vall d'Hebron University Hospital in Barcelona requesting her admission. The heel prick test performed on her son at the hospital where he was born showed results that were confirmed shortly afterward: severe combined immunodeficiency (SCID). This disease is caused by a disorder of several genes that prevent the development of the immune system, responsible for fighting all kinds of infections. The first response is to isolate the patient. So Madona and her son went to live in a hospital room while they waited for Misha to receive the treatment that would cure him. He had to reach three months of age or weigh five kilos. "I was with him in the hospital the whole time until they were able to perform a transplant. It was very hard, although Dr. Andrea Martín's medical team made everything very easy for us," Madona recalls. Severe combined immunodeficiency (SCID) is one of the many and diverse rare diseases that exist, and this Saturday, February 28th, is the day commemorated. "A disease is considered rare when it affects fewer than one in 2,000 individuals. It's a small part of the population, but precisely for that reason, extra effort must be dedicated to dissemination, so that affected families can have the option of consulting the appropriate referral centers and so that the country's healthcare centers are prepared to care for these patients, with complex conditions that affect..." says a pediatrician and member of the Pediatric Infectious Diseases and Immunodeficiencies Unit (UPIIP) at the Vall d'Hebron University Hospital.

A team from the Centre for Genomic Regulation (CRG) and Harvard Medical School has created an artificial intelligence (AI) model to identify which alterations are most likely to cause ultra-rare diseases, even when these mutations have never been observed in any person in the world. This system should aid in the diagnosis of pathologies that have historically been overlooked and underfunded by laboratories and pharmaceutical companies.

One day, she noticed, to her surprise, how her hand felt like it was going to give way. Then it was her leg. And she started stumbling and falling. "It must be my shoes, they're so worn out," she thought. After all, Carmen Cruïlles had been traveling the world for a year with the same shoes and a backpack. However, the tremors started in Australia. "It's just tiredness," or "It's anxiety," the doctors told her, dismissing it as unimportant. And yet, the unease grew inside her. When she met up with her mother in the Philippines in October to celebrate her 28th birthday, her mother, upon seeing her, told her seriously that she had to return to Barcelona "right away" to get a proper checkup.

Lia will turn three on December 28th. She doesn't walk independently – she crawls a lot, of course – but she's close to it, and although she communicates in her own way – she points and makes herself understood – she still doesn't speak beyond a few words. She's had multiple tests, and she's being monitored by specialists of all kinds, but they still haven't found the disease that explains the causes of this global developmental delay, although they suspect it could be a rare disease of genetic origin, explains her mother, Laura López Crespo, 39.

"No!" answers six-year-old Rosa embarrassedly when her mother, Blanca Flaquer, asks if she wants to say anything to the journalists interviewing her. Immediately afterward, she grabs a toy dog and runs off to show it to her four-year-old sister, Neus. In the hospital playroom, the two of them jump up and down, waiting for the strangers talking to their mother to leave. A few months ago, such a scene seemed unthinkable. Rosa was weak, had great difficulty moving, and her parents had to carry her on their shoulders to perform everyday activities like going to the bathroom. "She spent the entire summer in bed," Blanca recalls.

When Evelyn was born, her parents cried. A scan of the baby confirmed the news they had hoped not to receive: she suffered from spinal muscular atrophy (SMA), the same devastating disease that had already caused the death of their first child, Josephine, at just 15 months old.