New data on the genetics of Parkinson's disease.

We investigated the clinical and metabolic characteristics of Parkinsonian patients whose illness started before the age of 40. A pilot study of 32 of our own such cases revealed the existence of 3 subgroups: 1. Post-Encephalitic, 2. Onset and course with predominant tremor, 3. Onset and course with akinesia and rigidity. In this early onset group of patients, there was a 46% incidence of familial cases (as opposed to 10-15% in the general Parkinson populations). The cases with tremor onset had a high prevalence of essential tremor in their families, while those with an akineto-rigid onset had a high familial incidence of other cases of Parkinson's Disease. Familial grey hair, hypertension, diabetes and thyroidopathies appeared to be in higher than expected frequency.