'Diagnostic Anomaly' is a Health And Me Series, where we dive deep into some of the rarest of rare diseases. Here, we trace such diseases and what causes them. We also try to bring case studies around the same.Before biologist Silvana Santos set foot in Serrinha dos Pintos, a remote Brazilian town tucked into the mountains of Rio Grande do Norte, families had long lived with unanswered questions. As BBC reports, the children there were losing the ability to walk, often before reaching adulthood. No one knew why—until Santos arrived more than two decades ago and uncovered a genetic mystery that would put the town on the global medical map.A Name for the NamelessWith fewer than 5,000 residents, Serrinha dos Pintos had long operated as a close-knit, self-contained community. But beneath the surface of everyday life was a recurring pattern: a growing number of children unable to walk, gradually losing strength in their limbs. When Santos, a geneticist from São Paulo, arrived for what was meant to be a short holiday, she didn’t just see a town—she saw a puzzle.That puzzle led her to discover and name Spoan syndrome, as BBC reports, a previously unidentified genetic disorder that weakens the nervous system and affects motor control. It only develops when both parents carry the mutated gene, a scenario made more likely in Serrinha due to a high rate of intermarriage within extended families.The Town Where Family Ties Run DeepIn Serrinha, it’s common for cousins to marry—a reflection of the town’s geographic isolation and cultural traditions. Santos’s early studies found that more than 30% of couples in the town were related, and a significant number of these unions had produced at least one child with a disability.Worldwide, cousin marriages are not uncommon, but they come with higher genetic risks. In Brazil, such marriages account for only 1–4% of unions, compared to over 50% in countries like Pakistan. While most children born to cousin couples are healthy, the chance of recessive genetic disorders, like Spoan, doubles to about 5–6% per pregnancy.From Diagnosis to Global DiscoverySantos’s investigation didn’t end with just a diagnosis. What began as a three-month field visit evolved into years of research. She drove thousands of kilometres, collected DNA samples door-to-door, and documented family trees over coffee and conversation. Her work culminated in a groundbreaking 2005 study that identified Spoan syndrome and traced its genetic roots.The syndrome, she found, was caused by the loss of a tiny fragment of a chromosome, triggering a malfunction in brain cells. While local legends pinned the condition on a randy ancestor named Maximiano, genetic evidence suggests the mutation arrived over 500 years ago with European settlers—most likely Sephardic Jews or Moors fleeing the Inquisition.To date, 83 cases have been confirmed globally—including two in Egypt—strengthening the theory of a shared Iberian ancestry.Changing the Conversation Around DisabilitySantos’s discovery didn’t just change medical records; it reshaped local attitudes. Once dismissed with slurs like “crippled,” residents with Spoan are now recognised by name, their condition understood with empathy and scientific clarity. Many have received motorised wheelchairs and occupational therapy, improving not just mobility but also dignity.For Inés, whose two sons are among the oldest living Spoan patients in the town, the transformation is bittersweet. “We love our children the same,” she says, “but we suffer for them.” By age 50, most Spoan patients require full-time care.A Way To Go AheadWhile a cure for Spoan remains distant, education and awareness are proving powerful tools. Santos is now part of a major government-backed initiative to genetically screen 5,000 couples for risk of recessive diseases. The goal isn’t to discourage cousin marriages, but to provide informed choices for families like Larissa and Saulo—who only discovered they were distantly related after months of dating.Santos, now a university professor, continues to lead a genetics education centre and remains deeply involved in outreach in Brazil’s northeast. She may no longer live in Serrinha, but to locals, she’s more than a scientist.“She’s family,” says Inés.