The study will consist of a clinical component and a scientific component consisting of laboratory investigations of potentially useful biochemical (lipid and protein) markers. Up to 50 SLS patients of all ages, gender and ethnic origins will be enrolled. A detailed clinical evaluation will be performed to determine the presence and extent of disease involving the skin, nervous system and eyes. Clinical testing will include brain magnetic resonance imaging (MRI) and spectroscopy (MRS), electroencephalography (EEG), neurocognitive tests, ophthalmologic examination with retinal photographs and optical coherence tomography (OCT), photographs of the skin and tests of cutaneous transepidermal water loss. Laboratory investigations will include lipid analyses (e.g. fatty alcohols, farnesol, fatty acids, ether glycerolipids, etc.) of blood, skin and urine; proteomic analysis of skin (stratum corneum); and measurements of leukocyte fatty alcohol and farnesol oxidation. A skin biopsy (optional) will be obtained for electron microscopy, measurement of lanthanum perfusion (transepidermal water loss), and/or establishing keratinocyte cultures. Correlations between clinical abnormalities and laboratory measurements will be tested to identify the most useful biomarkers for future diagnostic and therapeutic studies. To characterize the progression of phenotypic features over time, patients <6 years of age will be followed yearly and patients ≥6 years of age will be followed every 3 years. In addition, a SLS patient registry will be established as a resource for future investigations in SLS.