Gaucher disease (GD) encompasses a continuum of clinical findings from a perinatal lethal disorder to an asymptomatic type. The identification of three major clinical types (1, 2, and 3) and two other subtypes (perinatal-lethal and cardiovascular) is useful in determining prognosis and management. GD type 1 is characterized by the presence of clinical or radiographic evidence of bone disease (osteopenia, focal lytic or sclerotic lesions, and osteonecrosis), hepatosplenomegaly, anemia and thrombocytopenia, lung disease, and the absence of primary central nervous system disease. GD types 2 and 3 are characterized by the presence of primary neurologic disease; in the past, they were distinguished by age of onset and rate of disease progression, but these distinctions are not absolute. Disease with onset before age two years, limited psychomotor development, and a rapidly progressive course with death by age two to four years is classified as GD type 2. Individuals with GD type 3 may have onset before age two years, but often have a more slowly progressive course and may live into the third or fourth decade. The perinatal-lethal form is associated with ichthyosiform or collodion skin abnormalities or with nonimmune hydrops fetalis. The cardiovascular form is characterized by calcification of the aortic and mitral valves, mild splenomegaly, corneal opacities, and supranuclear ophthalmoplegia. Cardiopulmonary complications have been described with all the clinical subtypes, although varying in frequency and severity.
The diagnosis of GD relies on demonstration of deficient glucosylceramidase enzyme activity in peripheral blood leukocytes or other nucleated cells. Carrier testing by assay of enzyme activity is unreliable because of overlap in enzyme activity between carriers and non-carriers. Identification of two disease-causing alleles in GBA, the only gene in which mutations are known to cause GD, provides additional confirmation of the diagnosis but should not be used for diagnosis in lieu of biochemical testing.
Gaucher disease (GD) is inherited in an autosomal recessive manner. At conception, each sib of an affected individual has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. Targeted mutation analysis can be used to detect carriers in high-risk populations (e.g., Ashkenazi Jewish persons). Because the carrier frequency for GD in certain populations is high (e.g., 1:18 in individuals of Ashkenazi Jewish heritage) and the N370S/N370S phenotype is variable, individuals who undergo carrier testing may be identified as being homozygous. Prenatal testing for pregnancies at increased risk is possible using assay of glucosylceramidase enzymatic activity and molecular genetic testing when both disease-causing mutations in a family are known.