Gaucher Disease Type 1

Gaucher disease type 1 is the chronic non-neurological form of Gaucher disease (GD; see this term) characterized by organomegaly, bone involvement and cytopenia.

Epidemiology

It represents around 90% of all cases of GD with an estimated prevalence of 1/100,000 in the general population.

Clinical description

Although the disease can be diagnosed at any age, half of patients are under the age of 20 at diagnosis. The clinical presentation is heterogeneous with occasional asymptomatic forms. It is characterized by the association of frequent asthenia, growth retardation or delayed puberty, splenomegaly (90% of cases) that may be complicated by splenic infarctions (sometimes superinfected), hepatomegaly (80% of cases) and in rare cases can progress towards fibrosis followed by cirrhosis. Bone anomalies are present in 80% of cases. They manifest as deformations, osteopenia that sometimes causes pathological fractures or vertebral compression, bone infarctions or even aseptic osteonecrosis. Involvement of other organs (rarely symptomatic pulmonary, renal and cardiac involvement) is less common. Pancytopenia is frequent and is associated with various degrees of thrombocytopenia (sometimes severe), anemia and, less frequently, leukoneutropenia. Polyclonal hypergammaglobulinemia is often present and is sometimes complicated by monoclonal gammapathy.

Etiology

GD type 1 is a lysosomal storage disease caused by a mutation in the GBA gene (localized to 1q21) that codes for the lysosomal enzyme, glucocerebrosidase. The deficiency in glucocerebrosidase leads to the accumulation of glucosylceramidase (or beta-glucocerebrosidase) deposits in the cells of the reticuloendothelial system of the liver, of the spleen and the bone marrow (Gaucher cells).

Diagnostic methods

Diagnostic methods involve ultrasound and magnetic resonance imaging (MRI) for the initial evaluation and subsequent monitoring of hepatosplenomegaly, radiography and bone scintigraphy to detect bone lesions and complications, osteodensitometry for the evaluation of osteopenia of the lumbar spine and femoral neck, and cardiac ultrasound for the detection of pulmonary arterial hypertension. An increase in certain biological markers, that are important both for the initial diagnosis and monitoring with or without treatment, is also observed: chitotriosidase, angiotensin converting enzyme, ferritin and tartrate-resistant acid phosphatases. Diagnosis can be confirmed by demonstrating a deficit in the enzymatic activity of glucocerebrosidase. In rare cases, genotyping may be of prognostic value: a patient with a homozygous N370S mutation in the GBA gene will not develop neurological disease.

Differential diagnosis

Differential diagnoses include other lysosomal storage disorders. The presence of Gaucher-like cells can be found in certain hematologic diseases (lymphoma, Hodgkin's lymphoma and chronic lymphocytic leukemia; see these terms).

Genetic counseling

The transmission is autosomal recessive

Management and treatment

The standard treatment for GD type 1 is enzyme substitution therapy, administered intravenously (e.g.: imiglucerase with European marketing authorization (MA) since 1997 and velaglucerase with a MA since 2010). Substrate reduction therapy (miglustat), administered orally, provides an alternative second-line treatment when enzyme substitution therapy is not suitable. Bisphophonates can also be proposed to prevent bone complications.

Prognosis

GD type 1 is not usually life-threatening. The functional prognosis, on the other hand, can be affected by sometimes serious bone complications.