MICE WITH TYPE-2 AND TYPE-3 GAUCHER-DISEASE POINT MUTATIONS GENERATEDBY A SINGLE INSERTION MUTAGENESIS PROCEDURE (SIMP)

Gaucher disease is caused by mutations in the gene encoding the lysoso mal enzyme glucocerebrosidase (GC). Three clinical types of Gaucher di sease have been defined according to the presence (type 2 and 3) or ab sence (type 1) of central nervous system disease and severity of clini cal manifestations. The clinical course of the disease correlates with the mutation carried by the GC gene. To produce mice with point mutat ions that correspond to the clinical types of Gaucher disease, we have devised a highly efficient one-step mutagenesis method--the single in sertion mutagenesis procedure (SIMP)--to introduce human disease mutat ions into the mouse GC gene. By using SIMP, mice were generated carryi ng either the very severe RecNciI mutation that can cause type 2 disea se or the less severe L444P mutation associated with type 3 disease. M ice homozygous for the RecNciI mutation had little GC enzyme activity and accumulated glucosylceramide in brain and liver. In contrast, the mice homozygous for the L444P mutation had higher levels of GC activit y and no detectable accumulation of glucosylceramide in brain and live r. Surprisingly, both point mutation mice died within 48 hr of birth, apparently of a compromised epidermal permeability barrier caused by d efective glucosylceramide metabolism in the epidermis.