Giulia Granki and Vitor Tavares
BBC Brazil
Silvana Santos still remembers her neighbors in the small town she visited 20 years ago, where many children had lost the ability to move.
The daughter of a man named Lolo near the entrance to the town, Režane at the end of the road, Marquinhos after the gas station, Paulinja by the school.
In Serinha dos Pintos, a remote town in northeastern Brazil with fewer than 5.000 inhabitants, biologist and geneticist Silvana Santos identified a previously unknown genetic disease and named it - spastic paraplegia-optic atrophy-neuropathy (SPANISH).
This disease, caused by a genetic mutation, affects the nervous system and gradually weakens the body.
It occurs only when a child inherits a mutated gene from both parents.
In her study, Santos described this disease as special for the first time in the world.
Thanks to this and her subsequent work, she was included in the BBC's list of the 100 most influential women in the world for 2024.
Before her arrival, the families had no explanation for the illness their children had contracted.
Today, locals are openly talking about SPOAN disease and genetics.
"She gave us a diagnosis we never had."
"After the research, help started to arrive - people, financial support, wheelchairs," says Marquinhos, one of the sufferers.
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Serinja dos Pintos: A world unto itself
On the street where she lived in São Paulo, the largest and richest city in Brazil, she had neighbors who were members of an extended family originally from Serinha.
Many of them were relatives in some lineage who were married to each other.
"There are a lot of people there who can't walk, but no one knows why," the Santos said of their hometown.
A neighbor's daughter, Zirlandia, had a serious illness.
Even as a child, her eyes moved uncontrollably, and over time she lost strength in her limbs and ended up in a wheelchair.
She needed help with even the simplest daily activities.
After years of research, Santos and her team concluded that these were symptoms of a previously unreported genetic disorder - SPOAN.
They later found 82 more cases worldwide.
At the request of her neighbors, Silvana Santos visited Serinha dos Pintos during her vacation.
He describes arriving there as "entering a special world," not only because of the lush nature and mountain views, but also because of the striking social phenomenon.
The more she walked and talked to the locals, the more surprised she was by the number of marriages between cousins.
Due to Serinja's isolation and very few settlers, a large number of residents are related, so marriages between relatives are much more likely than in other places.
Many couples didn't even know they were related until they got married.
Others knew, but believed that such marriages were more durable and provided stronger family support.
Marriages between cousins are relatively common in the world.
It is estimated that they account for about 10 percent of all marriages, and experts state that most children from such marriages are completely healthy.
However, the risk of transmitting harmful genetic mutations is increased in such marriages.
"If a couple is not related, the chance that their child will have a rare genetic disorder or disability is about two to three percent."
"In marriages between people who are related, this risk increases to five to six percent per pregnancy," explains geneticist Luzivan Costa Reis from the University of Rio Grande do Sul, in the Brazilian state of Rio Grande do Sul.
Later research showed that more than 30 percent of couples in Serinja were related, and a third of them had at least one child with a disability.
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The long road to diagnosis
Santos decided to find a medical diagnosis for the people of Serinha and began planning an extensive genetic research that required multiple visits and ultimately a move to the area.
During the first years of her research, she drove the 2.000 kilometers from São Paulo to Serinha many times.
She visited homes, took DNA samples, had coffee with locals, and listened to family stories, trying to find the mutation that causes the disease.
What was supposed to be three months of field work turned into years of effort and dedication.
In 2005, the team published a study that confirmed the existence of SPOAN disease in the interior of Brazil.
Dr. Santos' team discovered that the mutation occurs due to the loss of a small fragment of the chromosome, causing the gene to overproduce a key protein in brain cells.
"They say it comes from Maximian, the womanizer in our family," says farmer Lolo, whose daughter Režana has SPOAN.
Lolo, now 83 years old, married his cousin and never left Serinja.
He still keeps livestock, while his family takes care of his daughter Režana, who is unable to perform basic life activities.
However, the genetic mutation that causes SPOAN is much older than the legend of “old Maximian”.
It probably arrived more than 500 years ago, along with the first European settlers to northeastern Brazil.
"Genetic sequence analysis shows a strong European ancestry in the patients, which is consistent with historical evidence of the presence of Portuguese, Dutch and Sephardic Jews in the region," says Santos.
This theory was supported by the discovery of two cases of SPOAN disease in Egypt, and further research showed that Egyptian patients also have European ancestry, suggesting a common source in the Iberian Peninsula.
"It was most likely brought by related Sephardic Jews or Moors fleeing the Inquisition," explains Santos.
He believes there are still undetected cases around the world, especially in Portugal.
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Understanding risk
Although there has been no major progress in finding a cure so far, patient monitoring has brought about certain changes.
Režane remembers that they used to be called "cripples", and today they simply say that someone has SPOAN.
Wheelchairs not only gave sufferers greater independence, but also helped prevent deformities.
Previously, many who had this disease could only lie in bed or on the floor.
As the disease progresses, physical abilities deteriorate with age, and by around fifty, almost all patients become completely dependent on others.
This is also the case with the Ines children, who are among the oldest in Serinja.
Chiquinho, 59, can no longer speak, while Marquinhos, 46, has very limited communication skills.
"It's hard to have a 'special' child."
"We love them the same, but we suffer because of them," says Ines, who is married to a second cousin.
Larisa Queiroz, 25, niece of Chiquinho and Marquinhos, also married a distant cousin.
She and her husband Saulo discovered they had a common ancestor only after months of searching.
"In Serinha dos Pintos, after all, we are all relatives. We are related to everyone," says Larisa.
Couples like Larissa and Saul are the focus of a new study in which Santos is also participating.
The project, supported by the Brazilian Ministry of Health, envisages genetic screening of 5.000 couples to identify recessive genes associated with serious diseases.
"The goal is not to prevent marriages between cousins, but for couples to understand the genetic risks they can pass on to their offspring," says Santos.
Today, as a university professor, she runs a genetic education center and works to expand testing in northeastern Brazil.
Although he no longer lives in Serinha dos Pintos, Santos says that every time he visits, he feels like he's coming home.
"Silvana is like a family member to us," says Ines.
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