When HD appears in someone under the age of 20, the illness is recognized as Juvenile Huntington Disease (JHD). If you develop symptoms of Huntington's and are diagnosed with the disease before the age of 21, this is known as Juvenile Huntington's disease - sometimes. JHD is characterized by uncontrolled movements, loss of intellectual abilities, and emotional disturbances. JHD; Huntington disease, juvenile onset; Juvenile onset HD; JHD; Huntington disease, juvenile onset; Juvenile onset HD; Juvenile Huntington chorea See More. What is JHD? When George Huntington first identified Huntington disease in 1872, he suggested that the disease affects adults only. What Is Juvenile Onset Huntington's Disease (JHD)?.