Widespread abnormalities of radiocolloid distribution in patients with mucopolysaccharidoses

Mucopolysaccharidoses (MPS) are inherited disorders of lysosomal enzymes. We have examined the sites of accumulation of intravenously injected ⁹⁹Tc(m) sulfur colloid in order to assess the regional distribution of phagocytic function in ten patients with MPS: three with Type I (Hurler), five with Type II (Hunter), one with Type III (Sanfilippo), and one with Type VI (Maroteaux Lamy). Increased lung uptake was observed in 22 of 40 studies (55%) on the five patients with MPS Type II but in none of the 38 studies on patients with other MPS types. All MPS patients had diffuse reticuloendothelial (RE) marrow hypoplasia, despite normal or nearly normal hematocrits and hemoglobin levels, suggesting dissociation of the phagocytic and erythropoietic elements of the marrow. The eight patients with MPS Types I and II all had hepatomegaly and increased splenic uptake. Seven of these patients also had splenomegaly. The two patients with MPS Types III and VI did not have hepatosplenomegaly. These studies indicate that the lysosomal enzymic defect of MPS results in widespread abnormalities of the distribution of phagocytic function in the liver, spleen, bone marrow, and probably the lung as well.