Huntington Disease Juvenile form
Incidence
Autosomal dominant inheritance. 80 percent of juvenile patients inherit the defective gene from their father.
Clinical Characteristics
Huntington Disease Juvenile form: Approximately 10 percent of all patients with HD have onset before age 20. The youngest patient described had onset at age 2. Approximately 80 percent of juvenile patients inherit the defective gene from their father. For children who have onset up to 10 years of age (childhood onset), approximately 90 percent inherit the gene from their father, while approximately 75 percent of persons with adolescent onset (11 to 20 years) have paternal descent. In contrast to adult cases, bradykinesia and rigidity are conspicuous from early on, dominating the neurologic findings in about 50 percent of the cases. Chorea is present in almost all cases but is often of short duration and is superseded by rigidity. Frequent falls, dysarthria, clumsiness, hyperreflexia, and oculomotor disturbances are frequent in children with HD and occur early. Although difficult to assess in HD, cerebellar dysfunction is more prominent than in adult patients. Mental deterioration is first manifested by declining school performance. Over the years severe progressive dementia develops. Epileptic seizures, occurring in adult HD patients with a frequency similar to that in the general adult population (1 percent), are more common in early-onset cases with an estimated 30 to 50 percent of the juvenile patients affected. Partial or generalized, tonic-clonic, or absence seizures may all appear. Seizures should be differentiated from myoclonic jerks, which also rarely occur in adult cases. The epilepsy of juvenile HD patients is often difficult to control.
Precipitants
no
Provocation Tests
no
Diagnostic Procedures
Same as HD adult form