Among the inherited lipidoses, Gaucher disease (GD) is of particular importance to geneticists, since it is the most prevalent lysosomal storage disease. This disease is heterogeneous; the three clinically distintct subtypes all result from the deficient activity (5-20% of normal) of acid beta-glucosidase (beta-Glc). The objective of the proposed research is to investigate the nature of the clinical heterogeneity in this disease using biochemical, immunologic and molecular techniques. Using newly developed affinity techniques, large quantities of normal human beta-Glc will be purified to homogeneity for physicokinetic studies, amino acid sequencing and the production of additional polyclonal and monoclonal antibodies. The properties of the normal and residual beta-Glc from normal and GD subtype fibroblasts and or spleen will be determined by physical (chromatofocusing, peptide mapping, etc.) and kinetic (inhibitors and activators) studies. Polyclonal and monoclonal antibodies will be used to quantitatively (CRM levels) and qualitatively (epitope maps; enzyme maturation) compare normal and residual GD beta-Glc from each subtype. The toxic effects of substrate accumulation on reticuloendothelial function, including macrophage activation studies, will be assessed in cultured normal and GD monocyte/macrophages. A breeding colony for the canine analogue of human GD will be established. The residual beta-Glc activity, levels of toxic substrate accumulation and natural history of the canine disease will be characterized; these findings will provide the bases for evaluating future therapeutic endeavors in the animal analogue. Molecular techniques will be used to identify cDNA sequences for human beta-Glc. These cDNA sequences will be used to determine normal human beta-Glc gene structure and organization and to investigate the molecular defects in the human subtypes and the canine analogue of GD. These studies should provide insight into the molecular basis for the marked clinical variability in the GD subtypes. In addition, the animal model should provide the opportunity to evaluate transplantation and genetic strategies for the treatment of this and other inherited diseases.
