Aim of the study
The aim of the study was to perform biochemical laboratory diagnosis of mucopolysaccharidoses (MPS) among clinically suspected patients who referred to our department and to find out the frequency of each type of MPS among the studied patients.
Patients and methods
The study included 1249 patients who referred to our Biochemical Genetics Laboratory during the last 11 years for the diagnosis or exclusion of MPS. Each patient was subjected to quantitative determination of total urinary glycosaminoglycans (GAGs). Patients with high concentrations and patients clinically suspected to have MPS type-IV (104 patients of the 1249) were subjected to electrophoretic separation of GAGs in urine. The activity of the specific enzymes was fluorometrically assayed in the patients proved to have MPS by electrophoresis and in those suspected clinically to have Morquio syndrome (MPS type-IV) even with normal levels of total urinary GAGs or normal electrophoretic separation.
Of the 1249 patients screened for MPS, 548 (43.9%) patients had elevated total GAGs in urine. Using two-dimensional electrophoretic separation of GAGs extracted from urine in patients with high total GAGs and in patients suspected clinically to have Morquio syndrome, 278 (22.3% of the total 1249) patients proved to be affected by MPS. The specific enzyme assay in the 278 positive patients revealed the following distribution: MPS type-I (n=79) (28.5% of the 278), MPS type-II (n=46) (16.5% of the 278), MPS type-III B (n=18) (6.5% of the 278), MPS type-III, probable A, C, or D undetermined (n=25) (9% of the 278), MPS type-IV A (n=39) (13.9% of the 278), and MPS type-VI (n=71) (25.5% of the 278).
Quantitative determination of total GAGs in urine is a simple procedure to select patients for electrophoretic separation of GAGs. However, enzymatic assay is mandatory to confirm the MPS type, especially with the presence of enzyme replacement therapy for types-I, II, and VI and for prenatal diagnosis in coming pregnancies. The commonest MPS disorders in this study were MPS type-I followed by type-VI and then type-II.