Saccade testing in the diagnosis and treatment of type 3 Gaucher disease

Gaucher disease (GD) is an autosomal recessive lysosomal disorder caused by a deficiency of glucocerebrosidase. Partial deficiency produces type 1 GD (GD1), while severe deficiency yields the two less common types of neuronopathic GD (GD2 and GD3). GD3 can develop at birth up until age 14 years and is characterized by splenomegaly and fever, growth retardation, and bone changes with thinning of the cortices. Intellectual deterioration and neurologic manifestations, like seizures, occur later in the course of the disease. Oculomotor signs, such as squint, difficulty in generating horizontal saccades (saccadic initiation failure, SIF), and saccadic slowing, are present and may precede the emergence of overt neurologic signs by many years.¹ Enzyme replacement therapy (ERT) is effective in most GD1 while its efficacy in neuronopathic GD is less clear. It may relieve the systemic component of GD2, but does not reverse neurologic symptoms.² In GD3, reports are inconsistent. Some patients show partial neurologic remission and others show progression.^3,4 Data about eye movement modifications in GD3 both during its natural history and ERT are not available. In order …