Robert J Desnick, PhD, MD

For the past two decades, studies of the lysosome and the pathogenesis and treatment of lysosomal storage diseases have been a major research theme of this laboratory. For example, in Fabry disease (galactosidase-Gal A] deficiency), our group isolated the human-Gal A gene, developed novel overexpression methods, and made knock-out mice with Fabry disease for preclinical studies of enzyme and gene therapy. These basic science studies provided the rationale for the clinical trials of enzyme therapy that proved effective in this disease. These studied culminated in approval of enzyme replacement for Fabry disease by the FDA in April 2003. Current studies are directed to: 1) identify and characterize the structure/function relationships of mutations in the Gal A gene which cause Fabry disease, 2) develop novel therapeutic strategies to treat Fabry disease and other disorders due to protein misfolding by rescuing/stabilizing the misfolded protein with small molecule pharmacologic chaperones, and 3) develop stem cell and gene replacement strategies for these diseases.

Heme biosynthesis requires eight enzymatic steps to convert succinyl-CoA and glycine to the final product, heme. All eight enzymes are encoded by nuclear genes, with the first and last three enzymes being located in the mitochondria while the second through fifth enzymes are in the cytosol. The inherited porphyrias are inborn errors of heme biosynthesis, each resulting from the deficient activity of a particular enzyme.  Previously, our laboratory: 1) developed assays, 2) purified these enzymes, 3) isolated and characterized the cDNAs and genomic sequences encoding several enzymes, and 4) identified molecular lesions causing the different porphyrias. Recently, we developed knock-in mouse models for an erythropoietic porphyria, congenital erythropoietic porphyria (CEP), and are currently developing knock-in mice to generate an improved mouse model for a hepatic porphyria, acute intermittent porphyria (AIP). These models will permit studies of the cutaneous and acute neurologic pathophysiologies of these porphyrias, and facilitate the development of novel therapies. Current therapeutic efforts in these models include hematopoietic stem cell therapy for CEP and AAV-8 mediated hepatic-targeted gene therapy for AIP.