Juvenile Huntington’s disease and paediatric Huntington’s disease

Juvenile Huntington’s disease (JHD) is rare. It is usually defined as someone having an onset before 21 years. A more accurate description would be juvenile-onset HD. The origins of this definition are obscure but the distinction has been recognized for many years. The proportions of JHD cases may vary in different parts of the world but a figure of approximately five per cent is useful. JHD is not a separate category but rather part of the spectrum. Whilst it is still useful to think about the needs of young people in terms of the different ways they can present to a doctor some of the limitations of the definition will be explored. As part of the process of developing new drugs the European Medicines Agency (EMA) would like information on how the drug affects children. The term JHD does not cover this accurately so new term, paediatric Huntington’s disease (PHD) has been devised so that young people under the age of 18 years and currently affected by HD can be identified.

Juvenile Huntington’s disease: two case reports and a review of the literature

Background Huntington’s disease is a rare, autosomal dominant neurodegenerative disease characterized by motor, cognitive, and psychiatric symptoms. Usually, the disease symptoms first appear around the age of 40, but in 5–10% of cases, they manifest before the age of 21. This is then referred to as juvenile Huntington’s disease. According to the small number of cases reported in the literature, the course of juvenile Huntington’s disease significantly differs from adult onset and shows significant interpatient variability, making every case unique. Case presentation Our study aims to highlight the complexity and diversity of rare juvenile Huntington’s disease. We report cases of two Caucasian patients with chronic tics referred to the Huntington’s Disease Competence Center of Vilnius University Hospital Santaros Klinikos with suspicion of juvenile Huntington’s disease due to the appearance of chronic motor tics, and behavior problems. The diagnosis of juvenile Huntington’s disease was confirmed on both clinical and genetic grounds. In both cases described, the patients developed symptoms in all three main groups: motor, cognitive, and psychiatric. However, the first patient was experiencing more severe psychiatric symptoms; in the second case, motor symptoms (rigidity, tremor) were more prominent. In both cases, apathy was one of the first symptoms and affected patients’ motivation to participate in treatment actively. These two case descriptions serve as an important message for clinicians seeing patients with chronic tics and gradually worsening mood and behavior, indicating the need to investigate them for rare genetic disorders. Conclusions Description of these two clinical cases of juvenile Huntington’s disease provides insight into how differently it manifests and progresses in young patients and the difficulties the patients and their families face. There were different but painful ways for families to accept the diagnosis. Because the disease inevitably affects the patient’s closest ones, it is crucial to also provide adequate psychological and social support to all the family members. Establishment of multidisciplinary specialist centers for Huntington’s disease, as demonstrated by our experience, not only allows timely diagnosis and treatment plans but also ensures thorough disease management and care for patients and systematic support for their families.

A-095 Processing Speed Indicators in Juvenile Huntington’s Disease: Assessing CAG Repeat, Age of Onset, and Mood

Objective In adult onset Huntington’s Disease (HD), processing speed deficits and depression can be detected in the prodromal stages. These factors, along with CAG repeat length, may be predictive of age of symptom onset. However, less is known about the relationship between the aforementioned factors for patients diagnosed with Juvenile Huntington’s Disease (JHD). The current study aimed to investigate the relationships between age of symptom onset, CAG repeat, processing speed, and mood to improve prediction of symptom manifestation for JHD patients. Method Data was analyzed from the Kids HD study and included 30 participants (age at diagnosis M = 13.6, SD = 5.4, CAG repeat mean = 69, SD = 16). Bivariate partial correlations, independent t-tests, and regression analyses examined differences in processing speed across CAG repeat, age of onset, and depressive symptomology. Results CAG repeat length significantly predicted the natural log of age at diagnosis, β = −.59, t(25) = −3.59, p < .01, and significantly explained variance in the natural log of age at diagnosis, R2 = .35, F(1, 25) = 12.86, p < .01. Finally, results indicated that CAG repeat length also predicted processing speed abilities when controlling for depressed mood symptomology, R2 = .39, F(3,24) = 5.18, p < .01. Conclusion CAG repeat length holds predictive power for the age of diagnosis and for processing speed, even when accounting for covariate depressive mood indicators. Overall, results indicate evidence of impacted processing speed abilities given expansive CAG repeat numbers. This is consistent with a subcortical neurodegenerative process, such as HD.

Diagnosing Juvenile Huntington’s Disease: An Explorative Study among Caregivers of Affected Children

Objective: To investigate the reasons for the diagnostic delay of juvenile Huntington’s disease patients in the Netherlands. Methods: This study uses interpretative phenomenological analysis. Eligible participants were parents and caregivers of juvenile Huntington’s disease patients. Results: Eight parents were interviewed, who consulted up to four health care professionals. The diagnostic process lasted three to ten years. Parents believe that careful listening and follow-up would have improved the diagnostic process. Although they believe an earlier diagnosis would have benefited their child’s wellbeing, they felt they would not have been able to cope with more grief at that time. Conclusion: The delay in diagnosis is caused by the lack of knowledge among health care professionals on the one hand, and the resistance of the parent on the other. For professionals, the advice is to personalize their advice in which a conscious doctor’s delay is acceptable or even useful.

C-59 Sex Differences as Predictors for Executive and Intellectual Functioning in Juvenile Huntington’s Disease Patients

Objective Juvenile Huntington's Disease (JHD) is an extremely rare autosomal dominant neurodegenerative disease with onset in childhood or teenage years. Although there are many similarities with the adult form of the disease, JHD has a clinically distinct presentation. Some common symptoms include behavioral problems and cognitive decline. However, given the rarity of juvenile presentations, limited research exists regarding sex difference performances on executive and intellectual functioning in a JHD population. Thus, exploratory research was conducted to investigate such findings. Method Data from the Kids HD research study was analyzed (N = 58; mean age = 15.5, 50.8% female). Preliminary bivariate partial correlations, independent t-tests, and one way ANOVA tests were used to examine differences in executive and intellectual functioning between male and female participants. Results Performance significantly differed on several aspects of executive and intellectual functioning between sexes, including shifting attention (p = 0.007), verbal intellect (p = 0.019), and general ability intellect (p = 0.041). Significant differences were also observed regarding inhibition (p = 0.003), verbal categorical fluency (p = 0.021), and sorting (p = < 0.001). Conclusions Results suggest that there are significant differences in executive and intellectual functioning between sexes. In particular, males had more difficulty shifting attention, despite higher verbal intellect and higher general ability intellect. Females demonstrated greater inhibition, while males demonstrated stronger verbal categorical fluency and abstract reasoning. Between sexes, results indicate evidence of performance differences across tasks of executive and intellectual functioning. Such findings are consistent with a subcortical neurodegenerative process, such as HD.