The Natural History of Familial Dysautonomia

Define the phenotypic characteristics, severity and clinical evolution of FD on a patient-by patient basis. Investigators will enroll patients with FD in a multi-center observational natural history study to evaluate their biochemical, neurological and autonomic phenotype. Investigators will follow patients to systematically study the onset and scaled severity of all clinical problems. Investigators will define progression rates of patients outside of a clinical trial to distinguish between static and progressive features, a challenge in congenital neuropathies. Investigators will continue banking blood to look for ways to monitor the disease phenotypes. Biomarkers that quantify renal, cardiovascular, respiratory, skeletal and cognitive aspects of the disease will be evaluated. This information is relevant when monitoring toxicity to drugs in clinical trials. Detailed clinical follow-up of patients with FD will allow investigators to determine when standard of care therapies (e.g., non-invasive ventilation, gastrostomy feedings) should be initiated and how these impact survival outcomes.

Specific Aim 2: Develop ways to measure progressive neurological deficits as outcome measures for future clinical trials. Investigators will test the hypothesis that worsening gait ataxia and progressive visual loss are caused by ongoing neuronal degeneration. Investigators will develop precise outcome measures based on these deficits to test the efficacy of new treatments. Investigators will prospectively evaluate longitudinal changes in the retinal structure (with optical coherence tomography) and visual function in a cohort of patients with FD. Investigators will determine the extent and severity of retinal abnormalities in all patients and how they change overtime. Investigators will establish whether structural abnormalities in the retina are correlated with disease severity and look for functional correlates as measured by visual acuity and color discrimination. Following the recent discovery that gait ataxia in patients with FD is the result of sensory deficits, investigators will perform quantitative assessments of passive joint angle matching at the knee to measure proprioceptive acuity. Investigators will determine how these measures change overtime as well as their impact on daily function and quality of life.

An organized, multi-site natural history study of patients with FD will enable investigators to define disease-specific outcomes for testing new therapies, a major breakthrough for these patients. The study also offers a unique opportunity to understand better how the brain develops when devoid of crucial sensory inputs.