Mucopolysaccharidoses diagnosis in the era of enzyme replacement therapy in Egypt

Undegraded glycosaminoglycans (GAGs) induced by deficiency of enzymes are the primary cause of mucopolyscchardoses. Mucopolysacchardoses (MPS) are a group of rare lysosomal storage diseases (LSD). The quantification of a specific enzymatic activity is needed for accurate diagnosis. The objectives of this work were: first, to continue the study of mucopolysacchardoses disease in Egypt after the start of using the enzyme replacement therapy (ERT). Second, to define the commonest types among our population after 18 years experience with the disease. Third, to compare the different MPS types' distribution, diagnosed after the start of the ERT, to identify the impact of using ERT on the number and type of diagnosed patients.

Urinary GAGs were measured for all referred cases followed by two-dimensional electrophoretic separation for cases with high levels of GAGs; the specific enzyme activity was assayed for each type depending on the abnormal electrophoretic pattern obtained. Clinically suspected cases of Morquio syndrome were directly subjected to measuring the specific enzyme.

Out of 1448 suspected cases, 622 (42.9%) MPS patients were diagnosed revealing the following distribution: MPS I (172, 27.7%), MPS II (57, 9.1%), MPS III [(177, 28.5%: 134 type B and 43 types A, C or D)], MPS IVA (124, 19.9%), MPS VI (90, 14.5%) and MPS VII (2, 0.3%). MPS III was the most commonly diagnosed type followed by MPS I and MPS IVA. MPS IVA represented the most common type receiving treatment, followed by MPS I, MPS II and MPS VI.

The presence of treatment encouraged the affected families and physicians to seek diagnosis. MPS III was the commonest type among our studied group after 7 years of diagnosis, while MPS IVA was the commonest type receiving treatment.