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Meet the flok: Classical Homocystinuria

Meet the flok: Classical Homocystinuria

Our “Meet the flok” series profiles the inherited conditions of protein metabolism that make up our diverse community: Classical Homocystinuria, Maple Syrup Urine Disease, Organic Acidemias, Phenylketonuria, Tyrosinemia, and Urea Cycle Disorders. Each article highlights personal stories of resilience and the efforts of advocacy leaders to support individuals facing each condition. We hope this series will educate, inspire, and unite our flok community in a shared mission to improve treatment for our rare conditions.


The body cannot process the amino acid methionine causing a buildup of methionine and a toxic byproduct called homocysteine in the blood
 ~1,200 in the United States
1 in every 200,000-335,000  
Presenting Symptoms 
vision problems and lens dislocation
elongated limbs, osteopenia, osteoporosis, and broken bones
blood clots and stroke 
Central Nervous System
developmental delay, seizures, mood dysregulation
B6 supplement is primary treatment for some. If unresponsive to B6 supplement, treatment includes a low-protein diet, methionine-free formula, other B supplements, and a medication to lower homocysteine in the blood
Source: National Library of Medicine

Landon Skeens

In talking with 17-year-old Landon, whose intelligence, accomplishments, and confidence are striking, it’s hard to imagine doctors once gave him three weeks to live. Landon was born in West Virginia in 2007, only a year before the state implemented newborn screening for Homocystinuria. His parents noticed he lagged significantly in mobility and language milestones and felt something was not right.  They took him to 14 different pediatricians and specialists to get answers. One provider recommended imaging at Cincinnati Children’s Hospital, where they discovered bright white matter throughout Landon’s brain; this indicated tissue damage that limited his ability to develop cognitively and physically.  The treatment team believed he had a terminal brain disease with only weeks to live, but they awaited results from a blood test for an alternative diagnosis. The test came back positive for Classical Homocystinuria – a condition characterized by the body’s inability to break down the amino acid methionine which results in developmental delay, blood clots, and stroke if left untreated.  

For the first few years of his life, Landon had been eating high-protein foods his body could not metabolize, with toxic effects to his brain. His family immediately started him on medication, medical formula, and a low-protein diet; he began to improve. The ensuing years posed many challenges as Landon adjusted to a very restrictive diet and received physical, occupational, and speech therapy to work through his delays. With the right treatment and support, Landon progressed well and was released from his therapies in seventh grade.  

Driven to Succeed  
Landon reflects on his younger years stating, “As a junior in high school, it’s been such a transformation from what I was then to what I am now.” He takes Honors and AP-level classes, serves as the Editor-Chief of the school newspaper, acts as a youth leader at his local church, and has a lead role in a spring production of Tarzan. He plans to attend college and double major in English and education so he can become a high school English teacher.  

Landon, Young Adult with Classica HCUIn addition to his personal achievements, Landon also supports other youth living with Homocystinuria by facilitating virtual conferences for teens offered through HCU Network America. He notes that only three people in the state of West Virginia have the condition and stresses the importance of connecting with other people throughout the country to share challenges, ideas, and hopes for future treatments. 

While Landon’s story is one of perseverance and success, he shares some of the daily difficulties of life with Homocystinuria: “The mental side of living with Homocystinuria doesn’t get talked about enough; you feel so different with the diet when your family and friends are all eating food you can’t have. It’s hard.”  

In addition to the restrictive diet, he also takes 109 pills a day to provide his body with methionine-free protein and reduce homocysteine levels in his blood. He hopes for a cure or improvements in treatment to make diet and lifestyle easier to manage. Despite the challenges Homocystinuria presents, Landon refuses to let the condition limit his life or dreams– “It doesn’t define me.”  

Danae Bartke  
Executive Director of HCU Network America 

Early Challenges 
Danae received a diagnosis of Classical Homocystinuria at age 10 after her younger brother had a minor head injury that caused retinal lens detachment. Her family had spent the years prior seeking medical advice related to his delayed development and been dismissed by several providers. It took an ophthalmologist to name Homocystinuria as a potential cause and recommend screening for the whole family; Danae and her brother tested positive. 

Danae, Adult with Classical HCUAt the time of their diagnosis in 1995, there was no dietitian on the care team to support adjustment to the low-protein diet. In the absence of a nutrition expert, internet resources, and peer support, Danae struggled to stay on-diet. A blood clot in her wrist in 2009 changed everything. Determined to avoid a future medical crisis, Danae attended a low-protein cooking class offered through the PKU Organization of Illinois. She shares, “I learned more about navigating the low-protein diet in that one cooking class than in all the years since my Homocystinuria diagnosis and it was an event for an adjacent condition–PKU." 

Once she established a peer support system, Danae’s diet and overall health improved significantly. She continued attending PKU events, joined the organization, and eventually became their Board President in 2016. That same year, Danae attended a conference in Prague on Rare Disease Day and realized the widespread need for a Homocystinuria initiative. She co-founded HCU Network America with Margie McGlynn to educate patients and families, advocate for improved care, and advance research for the condition.  

A Pioneer in Homocystinuria Care  
HCU Network America fills a significant void for individuals and families living with Homocystinuria– prior to its founding there were no support resources that existed for the community. Danae spent the first few years developing and adapting tools for health systems, caregivers, and teachers. She coordinated virtual meetups and conferences to build community and partnered with the National Organization of Rare Disorders to create a financial assistance program for medical food.  

The focus of Danae’s current advocacy work is early detection and diagnosis of Homocystinuria. She notes that approximately 50% of Homocystinuria cases are missed because the newborn screening tests are not sensitive enough. The biomarker methionine is used to screen for the condition, but those with the condition have a low value of methionine in their blood at birth. Many state newborn screens use a methionine cutoff level too high to effectively detect positive cases. (Homocysteine is the primary diagnostic marker for Homocystinuria, but its testing process is more complex, and no states currently use it). HCU Network America advocates for legislation to lower state cutoff levels and ensure every baby born with the condition receives a diagnosis within those early days of life; prompt treatment is crucial to reduce adverse health outcomes. 

Danae encourages individuals with Homocystinuria and their families to contact their state newborn screening laboratories to promote improved processes – “The goal is timely and accessible treatment for everyone born with this condition.”  

The Power of Data to Improve Treatment 
Danae emphasizes the importance of data collection from individuals with Homocystinuria to better understand other systems of the body that are affected by the condition, uncover insights, and drive new treatment options.  

She recognizes the value in collaborating and comparing across metabolic conditions, stating, “There’s so much we don’t know about how the low-protein diet and medical formula affect us long-term. A tool like the flok app will provide a holistic view so we can correlate what we’re eating with our mood and other symptoms.”  

Through the advocacy and research efforts of HCU Network America, flok, and other organizations in the rare condition space, Danae envisions a future where the diagnosis and management landscape for Homocystinuria looks dramatically different. She encourages community members to share their stories and act, stating, “If we want better therapies and quality of life we need to show up and participate in research.”  

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