New Data on the Genetics of Parkinson’s Disease

Abstract

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 population). The cases with tremor onset had a high prevalence of essential tremor in their families, while those with an akinetorigid 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.These trends were confirmed in a larger series of 135 cases of early onset Parkinson obtained through a mail survey. When the same clinical material was analysed for the familial cases only, two new genetic subgroups emerged: 1) a familial metabolic akineto-rigid syndrome (with hypertension, familial diabetes, hypothyroidism and a more severe course) and, 2) a familial essential tremor-related Parkinsonian syndrome (with familial grey hair trait and hyperthyroidism). These new genetic syndromes along with the recently described “Familial juvenile Parkinsonism” require many further prospectives metabolic and clinical investigations for full characterization, but confirm our hypothesis that “idiopathic” Parkinson’s disease is not a single homogeneous entity.