Leukocyte Glucocerebrosidase Deficiency Diagnostic in Adult Gaucher's Disease with Negative Bone Marrow Biopsy. Some Properties of the Enzyme in Leukocytes and Spleen

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Abstract
A sixty‐one year‐old man with Gaucher's disease is described. The disease was manifested by splenomegaly, hypersplenism and elevations of serum acid phosphatase and immunoglobulin but no bone lesions were roentgenologically demonstrable and bone marrow biopsy failed to reveal Gaucher cells. The diagnosis was established prior to splenectomy by the finding of decreased β‐D‐glucoside glucohydrolase (β‐D‐GGH) activity in his peripheral leukocytes. Examination of the surgically removed spleen revealed Gaucher cells, a large excess of glucocerebroside and decreased β‐D‐GGH activity. Splenectomy was followed by normalization of haemoglobin, white cell and platelet counts and of the serum acid phosphatase and immunoglobulin levels. The patient's leukocyte β‐D‐GGH activity showed an optimum pH similar to that of normal leukocyte enzyme, about 5.4, using both glucocerebroside (Glc‐Cer) and 4‐methylumbelliferyl‐β‐D‐glucopyranoside (MU‐Glc) as substrate. The patient's spleen β‐D‐GGH activity showed a pH optimum of about 4.5, which differed slightly from that of normal spleen enzyme. The Km values of β‐D‐GGH in the patient's leukocytes for Glc‐Cer and MU‐Glc were 1.35 × 10−4 M and 3.6 × 10−3 M, respectively, i.e. in the normal range. The patient's splenic tissue Km values were for Glc‐Cer and MU‐Glc 0.52 × 10−4 M and 5.8 × 10−3 M, respectively, as compared to 0.30 × 10−4 M and 5.0 × 10−3 M in a normal control.