Huntington’s Disease (HD) affects approximately 30,000 people in the United States. Less than 10% of these people are under 20 years old at the time of diagnosis. These patients with juvenile, or early-onset, HD and their family members face significant and unique challenges as they battle a fatal, degenerative disease.

Symptoms of HD typically present in the third to fifth decade of life, but symptoms may appear as early as the first, or as late as the ninth, decade. The variation in age at onset is likely due to the number of defective trinucleotide repeats on the short arm of chromosome 4. Within the HD gene, more “CAG” repeats implies earlier onset of the disease. (Most juvenile HD patients have 60 or more repeat segments.) There is contradictory evidence about the rate of disease progression and clinical manifestations of HD related to the number of trinucleotide repeats.

While most adults with HD show symptoms of chorea — rapid, involuntary, jerky movements — juvenile HD presents a symptom profile different than adult-onset HD. The most common symptoms in juvenile HD include rigidity, stiffness, awkwardness in walking, and slurred speech. Seizures are also common in younger patients. Chorea is typically not present. Onset of the motor difficulties is usually used to define the age at onset.

Also significant in juvenile HD patients are severe cognitive and psychiatric disturbances. Since these are often the first disease symptoms to appear in young patients, HD is often not diagnosed until later in the disease process. This is particularly important in cases in which family history is either unknown or negative for HD. The cognitive dysfunction and loss of motor abilities is more severe in patients with juvenile HD.

Depression is common in juvenile HD patients, as well as aggression and impulsiveness. Adolescents with HD are particularly vulnerable to impulsiveness related to sexuality. Seizures occur in approximately 25% of juvenile HD patients. Some medication therapies can be implemented to treat some of these symptoms, but may have unwanted side effects in adolescents. The only FDA-approved drug for management of HD is not appropriate for use in children.

As HD progresses, children with the disease will lose the ability to walk, talk, dress themselves, and perform activities of daily living. They will require constant care and supervision. There is no cure for HD, and care is focused on symptom management. The team of medical professionals involved in the care of juvenile HD patients often includes a pediatrician, neurologist, psychiatrist, social worker or genetic counselor, and speech, occupational, and physical therapists.

Children diagnosed with HD will gradually lose the ability to attend school, perform routine tasks, or care for themselves. Families need immense amounts of emotional support from medical professionals, family members, and friends. The average life expectancy after diagnosis for a juvenile HD patient is less than 10 years.

Juvenile HD is a devastating disease, not just for the individual affected with the disease, but also for the entire family. With such a small number of people affected by HD, and an even smaller number affected by juvenile HD, researchers and drug and medical treatment manufacturers are reluctant to invest too much time and money into HD. But, there is hope, and advocacy groups are gaining in strength and voice, and new treatment options are currently under development.

References

Aubeeluck A, Brewer H (2008). Huntington’s disease. Part 2: treatment and management issues in juvenile HD. Br J Nurs, 17 (4), 260-263 PMID: 18414272

E. Gomez-Tortosa (1998). Severity of Cognitive Impairment in Juvenile and Late-Onset Huntington Disease Archives of Neurology, 55 (6), 835-843 DOI: 10.1001/archneur.55.6.835

P. Ribai, K. Nguyen, V. Hahn-Barma, I. Gourfinkel-An, M. Vidailhet, A. Legout, C. Dode, A. Brice, A. Durr (2007). Psychiatric and Cognitive Difficulties as Indicators of Juvenile Huntington Disease Onset in 29 Patients Archives of Neurology, 64 (6), 813-819 DOI: 10.1001/archneur.64.6.813

Shihui Xing, Ling Chen, Xi Chen, Zhong Pei, Jinsheng Zeng, Jinru Li (2008). Excessive blinking as an initial manifestation of juvenile Huntington’s disease Neurological Sciences, 29 (4), 275-277 DOI: 10.1007/s10072-008-0981-7