Unlocking the Mystery: A Rare Genetic Discovery Rewrites a Family’s Understanding of Autism

HOUSTON, TX – For years, Jennifer and Dr. Peter Johnson harbored a persistent, nagging suspicion: the autism diagnosis given to their son, Owen, didn’t quite capture the full spectrum of his evolving symptoms. What began as typical toddler developmental delays had morphed into something more complex, pushing them to seek deeper answers in the labyrinth of genetic science. Their quest, born of parental love and a neurologist father’s professional intuition, has now converged with groundbreaking research at the Jan and Dan Duncan Neurological Research Institute (NRI) at Texas Children’s Hospital, revealing a rare genetic mutation that promises to redefine understanding for Owen and countless others.

Owen, now 10, was diagnosed with autism at the age of three after exhibiting delayed speech and difficulties connecting with peers at his Houston preschool. Initial therapies offered glimmers of hope, but as he grew, the chasm between Owen and his twin sister, Alice, widened, and his vibrant early toddler years gave way to withdrawal and moodiness. “He had always been a very happy child in his early toddler years, and then he would just get so withdrawn,” Jennifer Johnson recalled, her voice still laced with the concern of those challenging years. “I was really concerned.”

Their journey led them to a crucial crossroads in 2021 when Owen’s doctor ordered genetic testing. The initial results, however, were a familiar disappointment: no new information, no clear explanation for Owen’s unique constellation of challenges. “It’s a helpless feeling,” said Dr. Peter Johnson, a neurologist himself, grappling with the limits of current medical knowledge. “If you don’t have an answer, then what can you do?”

Unbeknownst to the Johnsons, miles away, a scientific breakthrough was taking shape. Dr. Ryan Dhindsa, a principal investigator at the Duncan NRI and assistant professor at Baylor College of Medicine, was meticulously studying a suspicious gene mutation in his lab. His initial focus? Parkinson’s disease. What he soon discovered, however, would send ripples far beyond neurodegeneration, connecting directly to Owen’s perplexing symptoms and offering a clearer, albeit still complex, explanation. The gene, identified as ITSN1, proved to be a critical link not only to Parkinson’s but also to a spectrum of neurodevelopmental disorders, including those initially diagnosed as autism.

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The Search for a Deeper Explanation

Owen’s early childhood gave few overt clues to the underlying complexities that would later emerge. His parents initially attributed his delayed speech and strong fixations, like an intense fascination with the color red, to the quirks of toddlerhood. Even his preschool teachers expressed surprise when the Johnsons shared his autism diagnosis, suggesting his challenges weren’t overtly pronounced.

But as the years progressed, a profound shift occurred. The once happy, energetic child who loved to play and sing with his three sisters – older twins Audrey and Evelyn, and his own twin, Alice – began to change. He struggled to focus in school, and a poignant marker of his withdrawal was his cessation of the annual Mother’s Day song performance with his siblings. These changes fueled the Johnsons’ unwavering conviction that something more than a general autism diagnosis was at play.

“You just want so badly to do something for them and do everything you can to make it better for them,” Jennifer Johnson expressed, reflecting on the profound frustration of feeling unable to fully intervene. Without a specific underlying cause, their options were limited to adjusting Owen’s existing therapies and medications, a process that felt like navigating in the dark. This feeling of powerlessness underscored their determination to keep searching, to push for answers that conventional medicine had not yet provided.

A Serendipitous Discovery: The ITSN1 Mutation

While the Johnsons wrestled with uncertainty, Dr. Dhindsa and his team were engaged in a meticulous hunt for genetic risk factors associated with Parkinson’s disease across town. Their work involved delving into the vast landscape of the human genome, a daunting task considering it comprises over 3 billion base pairs of DNA.

Every child is born with approximately 70 de novo or spontaneous genetic mutations – changes in DNA that are not inherited from either parent. Most of these are harmless, silent alterations with no discernible effect. However, as Dr. Dhindsa explains, a tiny fraction can have profound consequences. “Sometimes we get unlucky, and that (mutation) hits a really important gene,” he noted, emphasizing the element of chance in genetic disorders.

To navigate this immense genetic data, Dhindsa’s lab employed sophisticated artificial intelligence algorithms. They sequenced DNA from a colossal cohort of roughly 800,000 patients, meticulously comparing genetic profiles of individuals with Parkinson’s disease against those without it. This large-scale, data-driven approach allowed them to identify subtle but significant patterns that would be impossible to detect manually.

Their analysis consistently flagged a specific gene: ITSN1. This gene is crucial for producing a protein called intersectin 1, which plays a vital role in endocytosis – a process essential for regulating synaptic communication between brain cells. Disruptions in this intricate cellular machinery can have far-reaching implications for neurological function. Over several years, further testing solidified their findings: individuals with a variant in the ITSN1 gene were found to be ten times more likely to develop Parkinson’s disease.

Then came the unexpected, yet profound, revelation. As the researchers continued to study ITSN1, they observed a curious pattern: variants of this gene were also disproportionately present in another patient group – children diagnosed with autism or other neurodevelopmental disorders. This serendipitous discovery suddenly bridged two seemingly disparate fields of neurological research, suggesting a common genetic thread linking neurodevelopmental challenges in childhood with neurodegenerative conditions later in life.

An Obscure Answer Emerges

The first tangible link between this cutting-edge research and Owen’s personal journey arrived in mid-2022. Jennifer Johnson opened an email from the lab that had performed Owen’s initial genetic testing a year prior. The letter explained that the lab had recently become aware of new research indicating ITSN1 variants were “likely pathogenic,” meaning there was strong evidence they could cause neurodevelopmental disorders akin to autism. While a significant step forward, the letter offered no further specifics, leaving the Johnsons to grapple with a new piece of the puzzle that was still largely undefined.

Frantically, the Johnsons scoured the internet, seeking to understand what this finding meant for Owen’s future. Their search yielded little, and even Owen’s trusted doctors and therapists were unfamiliar with ITSN1. “There was a little piece of the puzzle that was maybe filled in, but it just didn’t give a clear enough picture,” Jennifer said, articulating the bittersweet feeling of having a potential answer that remained frustratingly out of reach.

Undeterred, the Johnsons sought out pediatric neurologist Dr. Sarah Risen at Texas Children’s Hospital the following year. Dr. Risen, equipped with specialized knowledge in rare neurological conditions, performed additional genetic testing that definitively confirmed the ITSN1 variant in Owen. This confirmation was a critical turning point, allowing Dr. Risen to adjust Owen’s medications to those that might specifically address the pathways influenced by the ITSN1 variant, moving from symptomatic treatment to a more targeted approach.

The true breakthrough, however, came in early 2025. Dr. Risen informed the Johnsons that a scientist at the Duncan NRI was actively studying the ITSN1 variant as part of his Parkinson’s research and had identified its link to neurodevelopmental disorders. She immediately arranged a meeting between the family and Dr. Ryan Dhindsa, finally connecting the disparate threads of Owen’s experience with the leading edge of genetic discovery.

The Puzzling Nature of ITSN1-Related Syndrome

The meeting with Dr. Dhindsa illuminated both the promise and the profound complexities surrounding ITSN1. His lab is one of only a handful globally investigating this particular gene, primarily due to its rarity. An estimated one in 5,000 people are born with an ITSN1 variant, making it an elusive subject of study.

The variant presents a fascinating enigma for researchers. It’s unclear precisely how or even if it will manifest in an individual. In approximately 60% of patients who inherit the variant from a parent, that parent appears to be entirely unaffected, showcasing the concept of incomplete penetrance – where individuals with the same genetic mutation may or may not express the associated traits. This variability adds another layer of complexity to understanding its impact.

Dr. Dhindsa notes that children with ITSN1-related syndrome are typically diagnosed initially with autism and ADHD, mirroring Owen’s early journey. Yet, a curious paradox exists: most adults with ITSN1 variants who later develop Parkinson’s disease have no documented history of neurodevelopmental disorders during their childhood. This suggests a multifaceted role for the gene, potentially impacting brain development and function differently across the lifespan or under varying genetic and environmental influences.

Such profound mysteries are not uncommon at the Duncan NRI. The institute, under the visionary leadership of its founding director, Dr. Huda Zoghbi, specializes in investigating genes like ITSN1 that are intricately linked to rare pediatric brain disorders. Dr. Zoghbi, a renowned neurogeneticist, emphasizes the fundamental importance of this approach: “Genes are a good entry point for understanding how the brain doesn’t function properly or why it’s vulnerable to degradation later in life.” This foundational knowledge is paramount, she explains, because it empowers scientists to identify strategies to prevent harmful genetic variants from expressing, or to develop targeted medications and therapies to treat them. “Once you know that,” she stated, “we can then begin to say, ‘How do you reverse it?’”

Complex Genetic Research Paving the Way

The Johnsons met Dr. Dhindsa last year, shortly after he co-authored a landmark study directly linking ITSN1 variants to a heightened risk of Parkinson’s disease. Their family is now among roughly 20 worldwide actively collaborating with Dhindsa’s lab, contributing invaluable data to further unravel the complexities of ITSN1-related syndrome. This collaborative approach, integrating patient experiences with scientific investigation, is critical for rare diseases.

A key component of this ongoing research is a comprehensive natural history study. Dhindsa’s lab will meticulously follow individuals with ITSN1 variants over many years, observing and documenting how their symptoms progress. This longitudinal data is crucial for understanding the full phenotypic spectrum of the disorder, which varies significantly. Some individuals experience relatively mild symptoms, such as ADHD or moderate learning disabilities. Others face more severe challenges, including seizures or profound language regression, gradually losing the ability to speak as late as their teenage years. Owen’s participation in this study provides vital insights into the trajectory of the syndrome.

Beyond observational studies, the Duncan NRI is employing cutting-edge techniques in complex genetic research. In a remarkable feat of biomedical engineering, Dhindsa’s lab took a sample of Owen’s skin cells and, through sophisticated gene-editing technology, "reprogrammed" them into induced pluripotent stem cells. These stem cells were then meticulously transformed into brain cells – some retaining the ITSN1 variant, others modified to exclude it. This entire, painstaking process took approximately 18 months, creating a personalized in vitro model of Owen’s brain cells that allows researchers to study the precise cellular and molecular effects of the ITSN1 mutation in a controlled environment.

Simultaneously, the lab is utilizing animal models, specifically mice, to investigate how the ITSN1 variant affects the brain in vivo. Researchers will observe these mice across their lifespans, carefully monitoring how the variant impacts crucial cognitive functions such as learning, memory, and social behavior. This dual approach, combining cellular and animal models, offers a comprehensive platform for understanding the disease mechanisms.

Dr. Dhindsa candidly acknowledges the vast unknowns that remain. “There’s very little understanding of how this gene actually can lead to either autism or Parkinson’s, and critically, why some people can be walking around with the variant and healthy while others can’t,” he said. “We’re trying to understand all the different components of this puzzle.” This underscores the profound complexity of genetic diseases and the dedication required to untangle them.

Bringing Families on the Journey: Hope and Resilience

The work at the Duncan NRI, while offering immense promise for therapies and medications for rare diseases, is inherently a long and arduous process. Dr. Zoghbi emphasizes the critical importance of integrating patient families into every step of this journey. Many families initially experience a profound sense of relief upon learning there’s a genetic explanation for their children’s developmental challenges. However, that initial optimism can wane as they confront the protracted nature of scientific research. It is therefore paramount, Zoghbi stresses, that Duncan NRI researchers ensure these families feel deeply included and informed throughout the process.

“We give them hope, but we also take them along with us on the journey,” she affirmed. “They know we’re doing all the steps, one by one, and as fast as we can.” This commitment to transparency and partnership fosters trust and sustains hope even through periods of slow progress.

For the Johnsons, the uncertainty surrounding ITSN1-related syndrome can still be frightening. Hearing stories of children older than Owen who have lost the ability to speak due to the variant is a stark reminder of the potential challenges ahead. Determining the most effective therapy for Owen is also an ongoing challenge; due to the rarity of ITSN1 variants, the Johnsons often find themselves sharing new scientific discoveries with his therapists, actively educating them on the evolving understanding of his condition.

Despite these hurdles, the family remains remarkably optimistic. Owen and Alice recently celebrated their tenth birthday. Owen finds joy in playing tag with his siblings and has recently developed a keen interest in dinosaurs, a testament to his vibrant spirit. He recently started a new medication that has significantly improved his mood and concentration, offering a tangible positive shift. The family’s recent move to Tomball has also brought positive changes, with his school accommodating his unique learning needs by having therapists work with him directly in class throughout the day. “They help me with work at school,” Owen shared, “They help me pay attention.”

The Johnsons are profoundly encouraged by the breakthroughs occurring at the Duncan NRI related to ITSN1. While Owen will likely require support throughout his life, his parents hold onto the powerful hope that researchers can discover therapies or medications that will help him avoid regression and foster greater independence. “Of course, we would like for him to be an independent, functioning adult one day,” Jennifer Johnson articulated, her voice imbued with a parent’s deepest aspiration. “We’re hoping (Dhindsa’s) work can yield that.”

Owen’s story is a compelling narrative of scientific pursuit intersecting with profound personal resilience. It highlights not only the incredible advancements in genetic research but also the enduring power of families to champion their children’s well-being, pushing the boundaries of what is known and embracing the journey of discovery, one step at a time. The path forward for ITSN1-related syndrome is long and complex, but with dedicated research and unwavering family support, the hope for clearer answers and effective interventions shines brightly.