European journal of molecular biology and biochemistry

NEW GENERATION TECHNIQUES IN RAPID DIAGNOSIS OF LYSOSOMAL STORAGE DISORDERS

Jyotsna Verma*, Divya Catherine Thomas*, Ishwar Chand Verma*

j4verma@yahoo.com

Fluorometry, MS/MS, lysosomal enzymes, diagnostic techniques, inherited metabolic diseases, lysosomal storage disorders

Emergence of different therapeutic approaches for lysosomal storage disorders (LSDs) has created interest in early diagnosis and intervention. The diagnosis is mainly done by detecting enzyme deficiency in plasma/ leukocytes/ cultured fibroblasts/ dried blood spots (DBS) by fluorometric/ spectrophotometric methods using artificial/ natural fluorogenic 4 methylumbelliferone/ chromogenic 4 nitrocatecol substrates. The process usually involves complex sampling, testing and validation procedures which causes great difficulties in reaching a definitive diagnosis. Therefore in recent years, efforts are being made to transform the conventional fluorometric methodology of low precision into microchip and immune capture assays using single/ multiplex platforms- digital micro fluid (DMF) and Luminex respectively for rapid screening of LSDs. Implementation of automated systems (MS/MS & LC-MS/MS) are enabling the simultaneous screening of number of LSDs in a single analysis at early course of disease. But every technique has its own advantages and limitations. In present study, we have shared 10 yrs of our experience (2004-2014) in the diagnosis of 1120 cases (24.6%) for 25 different LSDs out of 4542 suspected individuals whose samples received in our genetic centre using conventional fluorometric assays (single analyte analysis technique). Diagnostic efficiency of these assays is compared with the data reported by other researchers from various countries using latest high through-put technologies. Though, fluorometric enzyme assays have been referred as the gold standards for timely diagnosis followed by molecular confirmation, MS/MS based assays seem to have great clinical prospects in future for the diagnosis of IMD due to multiplexity, high precision and specificity. Our experience states that with the advancement of the technologies, there is a need of a defined quality assurance program for the laboratories/ health professionals in order to provide such services. Accurate diagnosis at early stages of life will have a great impact on genetic counselling for further management of the disease.