In Singapore, a two-year-old boy named Teyden has become the only known person in the country to carry a diagnosis of ZTTK syndrome — a rare genetic condition affecting fewer than 400 people worldwide, identified only a decade ago. Caused by a single altered gene that disrupts the brain's developmental instructions, the syndrome touches nearly every dimension of a young child's growth: movement, breath, cognition, and the fragile rhythm of daily life. His parents, who chose to welcome him before they had a name for what he carried, now navigate a path with few maps — finding their footing thro
Singapore Boy's Rare ZTTK Syndrome Diagnosis Highlights Early Intervention Benefits
A 2-year-old boy experiences developmental delays, seizures, and respiratory complications from ZTTK syndrome, requiring intensive physiotherapy and anti-seizure medication management.
We are managing and trying to stay as positive as much as possible.
Mark
Why does early intervention matter so much for a condition this rare? It seems like there's not much medical history to draw from.
Mimi
The thing is, ZTTK affects brain development across multiple systems—motor skills, speech, cognition, breathing. Early physiotherapy and specialized programs can help the brain form new pathways and strengthen what's working. Teyden couldn't sit up on his own before intensive sessions; now he can. That's not a cure, but it's real progress.
Luke
But we should be clear: the source doesn't say that early intervention prevents seizures or changes the underlying genetic condition. It improves function and outcomes, which is significant, but it's not reversing the diagnosis.
Mark
Right. So the seizures—they're a separate problem that needs medication?
Mimi
Yes. About half of ZTTK patients have seizures. Teyden's on anti-seizure drugs, but they didn't prevent all episodes. When he got COVID and a fever, he had another one. That's the scary part—he's vulnerable in ways that go beyond just the developmental delays.
Luke
And here's what I want to flag: we don't know the long-term trajectory. The condition was only identified in 2016. There are 400 known cases worldwide. There's no established natural history, no long-term outcome data. The family is managing day-to-day, but nobody really knows what his teenage years or adulthood will look like.
Mark
That must be terrifying for the parents.
Mimi
It is. But they're also part of a support network now—other families online, therapists, geneticists. They're not alone in it, even though Teyden is the only known case in Singapore.
Luke
The diagnosis itself took time. Symptoms overlap with other conditions. If it hadn't been for the prenatal finding and the genetic testing, would they still be searching for answers?
Mimi
Probably. The source says misdiagnosis and missed diagnosis are common with ZTTK because it's so rare. Standard tests don't catch it. You need genetic sequencing, and you need to think to look for it.
Mark
So the prenatal diagnosis was actually a gift in that sense.
Mimi
In a way, yes. They knew something was different from the start. They had time to prepare, to connect with specialists, to begin intervention early. That head start matters.
O Pulso
- A condition affecting fewer than 400 people globally has quietly arrived in Singapore, carried by a two-year-old boy whose parents had no name for his struggles until genetic testing reached a laboratory in the United States.
- Seizures lasting up to 11 minutes, skin turning blue, and a respiratory system already compromised by ZTTK made a COVID-19 infection the most terrifying chapter yet in Teyden's short life.
- Because ZTTK's symptoms mirror dozens of other neurological conditions, diagnosis remains elusive — roughly 80 percent of rare diseases present with overlapping signs that standard tests are not designed to catch.
- Twice-weekly physiotherapy has transformed a child once described as 'really floppy' into one who can now sit independently, suggesting that early intervention, even without a cure, meaningfully reshapes the trajectory.
- With no local precedent and an uncertain prognosis, Teyden's family has turned to a global Facebook community of ZTTK families, finding in shared experience the guidance that medicine alone cannot yet provide.
In Singapore, a two-year-old boy named Teyden has become the only known person in the country to carry a diagnosis of ZTTK syndrome — a rare genetic condition affecting fewer than 400 people worldwide, identified only a decade ago. Caused by a single altered gene that disrupts the brain's developmental instructions, the syndrome touches nearly every dimension of a young child's growth: movement, breath, cognition, and the fragile rhythm of daily life. His parents, who chose to welcome him before they had a name for what he carried, now navigate a path with few maps — finding their footing through therapy, medication, and the quiet solidarity of families scattered across the world who share the same rare grief and the same rare hope.
Tizane Woo was 20 weeks pregnant when an ultrasound revealed that her son's brain was developing differently — his head smaller than expected, his cerebellum undersized. Amniocentesis confirmed he carried an extra chromosome, inherited from her. When offered the option to terminate, she and her husband said no. He was theirs.
Teyden Hamilton Ho is now two years old. At 15 months, after genetic samples from all three family members were analysed in the United States, he was diagnosed with Zhu-Tokita-Takenouchi-Kim syndrome — ZTTK — a condition named after four researchers who first described it in 2016. It is caused by a single altered gene that acts, as one geneticist explains, like a broken editor: it garbles the instructions that govern how the brain develops. Roughly 400 people worldwide are believed to have it, a figure that reflects both the condition's rarity and how recently medicine learned to recognise it.
For Woo, the diagnosis arrived as a collision — guilt that she had passed the gene to her son, and relief that the uncertainty finally had a name. Physiotherapists guided the family through Teyden's care. He began attending therapy twice a week, working on posture and motor control. By June, a child once described as almost entirely without muscle tone could sit up on his own. He also exhibits a known neurological feature of the syndrome: rhythmic self-stimulation that his parents have learned, carefully, to accommodate rather than suppress.
In late May, Teyden had his first seizure. His parents did not recognise it at first — he was asleep on the ventilator that helps him breathe when he began jerking and his skin turned blue. When a second seizure followed weeks later, they were ready with a camera, capturing 11 minutes of footage for his doctor. He is now on anti-seizure medication, though it has not prevented every episode. A subsequent COVID-19 infection, compounded by his respiratory vulnerabilities, triggered another seizure and became, his mother said, the most frightening moment of his two years.
Teyden has recovered. He attends an early intervention programme in Upper Thomson Road — the youngest student there, and by his mother's account, the loudest. His father describes a boy who loves being part of conversations and babbles with enthusiasm, even without words. The family has found community in a global ZTTK support group, connecting across continents with other parents navigating the same rare and uncertain road. Teyden is the only person in Singapore known to have the condition. 'We do not know what holds for him in the future,' his mother said. 'We are managing and trying to stay as positive as much as possible.'
Tizane Woo was 20 weeks pregnant when her doctor saw something troubling on the ultrasound. Her son's head was smaller than it should have been. The cerebellum—the part of the brain that controls balance and coordination—measured too small. A week later, after amniocentesis, she learned the child carried an extra chromosome, inherited from her. When the doctor asked if she wanted to terminate the pregnancy, she and her husband said no. He was theirs.
Teyden Hamilton Ho is now two years old. At 15 months, after blood samples from all three family members were sent to a laboratory in the United States, he received a diagnosis: Zhu-Tokita-Takenouchi-Kim syndrome, or ZTTK. The condition is named after four researchers who first identified it in 2016. It is caused by a single altered gene on a non-sex chromosome, and it disrupts brain development in ways that cascade through a child's entire nervous system. About 400 people in the world are believed to have it—a number that reflects how recently the disease was recognized and how easily it can be missed.
The SON gene, as geneticist Jeannette Goh explains it, acts like an editor. It reads the instructions that other genes carry, many of them related to how the brain develops. When the SON gene is broken, those instructions become garbled. Children with ZTTK experience intellectual and cognitive delays. They struggle with motor control, breathing, and speech. The condition's symptoms overlap so thoroughly with other neurological disorders that misdiagnosis is common. Genetic counselor Priscella Chia notes that about 80 percent of rare diseases present with vague, overlapping symptoms, and standard medical tests are designed to rule out common conditions, not to pinpoint rare ones. The possibility of ZTTK being missed entirely remains high.
When Teyden was diagnosed, Woo felt a collision of emotions. She carried guilt—she had passed the altered gene to her son. But she also felt relief. After months of uncertainty, they finally had a name for what was happening. Physiotherapists taught her and her husband how to manage his care. Teyden began attending sessions twice a week at a therapy center, working on posture, trunk control, and motor function. By June, after intensive treatment, he could sit up on his own for stretches of time. Before that, he had been what Woo calls "really floppy," with almost no head control. He also exhibits a known neurological feature of ZTTK: he shakes his arms and bangs his head against the back of his high chair. When his parents try to stop him, he cries. They have cushioned the chair, but he seems to understand the softness and strikes harder.
At the end of May, Teyden began having seizures—a symptom that affects between 50 and 55 percent of ZTTK patients. His parents did not recognize the first one. He was asleep on his BiPAP machine, a non-invasive ventilator that helps him breathe. He began jerking. Foam came from his mouth. His skin turned blue. They called an ambulance. When a second seizure occurred weeks later, they were ready with a camera and captured 11 minutes of footage to show his doctor. Teyden is now on anti-seizure medication, but the drugs have not prevented all episodes. When he contracted COVID-19 and developed a fever, another seizure followed. For a child with respiratory vulnerabilities, COVID-19 posed a significantly higher risk of severe illness or breathing complications. "It was the scariest point of the two years of his life," Woo said.
Teyden has recovered. He plays with the family's two pets and attends an early intervention program at a center in Upper Thomson Road, where he is the youngest student and, his mother notes with a laugh, the loudest. His father, Ho Jun Han, a 27-year-old data centre operator, says the boy loves being part of conversations and babbles constantly, though he cannot yet form words. The family has joined a Facebook support group for ZTTK based in the United States. Teyden is the only person in Singapore known to have the condition. Through the online group, his parents have connected with other families navigating the same diagnosis, sharing strategies and offering each other support across continents. "We do not know what holds for him in the future because this condition is super rare," Woo said. "We are managing and trying to stay as positive as much as possible."
Citações Notáveis
The gene acts like an editor for other genes and helps the body to read other gene instructions and many of these other genes are related to brain development.— Geneticist Jeannette Goh, explaining how the SON gene functions
About 80 per cent of rare diseases present with vague, overlapping symptoms. Standard medical tests usually rule out common conditions rather than pinpoint a rare one.— Genetic counselor Priscella Chia, on why ZTTK is often missed or misdiagnosed
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