Mechanisms of Gaucher disease pathogenesis.

Gaucher disease is caused by mutations in the Gba1 gene encoding an acid β-glucocerebrosidase (GBA1), the lysosomal hydrolase which breaks down glucosylceramide (GlcCer). In Gaucher type 1 disease the accumulation of this simple glycolipid is mainly restricted to tissue phagocyte lysosomes resulting ultimately in hepatomegaly, splenomegaly and osteopenia. Lower residual GBA1 levels leads to neuronal storage, in types 2 and 3 neurological symptoms are characterised by acute (death at age 2) or subacute onset, respectively. The links between cellular changes and clinical manifestations are largely unknown but are the key to the development and monitoring of new therapies. The newcomer to Gaucher disease is likely attracted to the apparent simplicity of an autosomal recessive disorder which promises to unravel the critical GlcCer function in normal cells (GlcCer is widespread, it’s even present in some bacteria—also, mouse and fly GlcCer knockouts die at embryo stage). However, closer acquaintance reveals not a classic Mendelian disorder—sometimes even monozygotic twins have different symptoms—and studies at the cellular level have so far failed to reveal clear GlcCer functions. Now a team led by Ellen Sidransky at the NIH has taken what appears to be a big step forward by producing two in vitro models of Gaucher cells (1).