'Non-neuronopathic' Gaucher disease reconsidered. Prevalence of neurological manifestations in a Dutch cohort of type I Gaucher disease patients and a systematic review of the literature.

Gaucher disease is a lysosomal storage disorder, which is classically divided into three types. Type I Gaucher disease is differentiated from types II and III disease by the absence of nervous system involvement. However, an increasing number of reports has emerged on neurological manifestations in patients with type I Gaucher disease. Whether a strict division in three different phenotypes is still valid has been the subject of debate. The main objective of this study was to provide scientific arguments whether a distinction between type I (non-neuronopathic) and types II and III (neuronopathic) Gaucher disease should be maintained. We investigated retrospectively a large Dutch cohort of type I Gaucher disease patients for the prevalence of neurological manifestations and provide an overview of the literature on this topic. A diagnosis of a neurological disease was made 34 times in 75 patients. Forty-five patients reported at least one neurological symptom during the median follow-up time of 11 years. The literature search revealed 86 studies in which type I Gaucher disease patients or carriers of a glucocerebrosidase mutation were described with a neurological disease or a condition which is known to be associated with neurological disease. In conclusion, the term non-neuronopathic Gaucher disease does not seem to be an appropriate characterization of type I Gaucher disease. However, the neurological signs and symptoms in type I Gaucher disease are of a totally different kind from and, in the majority of cases, of much less severity than the signs and symptoms associated with types II and III disease Therefore, type I disease should be classified as a separate phenotype.