[priyasaravanan_1406]

Lysosomal storage disorder (LSD), the very rare inherited disorder is a condition due to lysosomal dysfunction of the cell. Lysosome, the organelle of a body cell, acts as the recycling centre of the cell by breaking down the waste substances (substrates) generated in the cell into useful product which in turn is utilized by the cell. Also, any foreign body entering the cell is evaded by lysosome. Lysosome also digests dead cells and thus its role in short can be explained as cellular substrate management and cellular digestion.

The history of Lysosomal storage disorder dates back to 1880’s even before the discovery of lysosome in 1960s. About 40 different hydrolytic enzymes (proteins) are essential for proper functioning of the lysosome. Each of these enzymes is responsible for reduction of particular substrate and deficit or absence of any of these enzymes result in substrate accumulation in the cell causing various diseases categorized under LSD. To name a few, they are Tay-Sachs disease, Gaucher disease, pompe disease, Niemann-pick disease, Farber disease, Krabbe disease, Sandhoff disease, Schindller disease, salla disease and Wolman disease. The most affected age group is children, once inherited the disease, they die even before 15 years of age. Various researches on LSD have proved the average ratio of prevalence of this disorder is 1 in 5000 live births.

The various signs and symptoms of LSD depend on the type of enzyme deficient and the particular type of cell (liver cell, brain cell and so on) which is affected due to Lysosomal dysfunction. Some of the symptoms are reduced motor skills, growth retardation, enlarged organs and rare facial features. Based on the symptoms, the adversity of the disorder is diagnosed by various techniques like enzyme assay and mutation analysis.

In enzyme assay technique, the enzyme levels in patients with LSD are assessed and compared to the desirable level. This technique is even applicable to testing fetus suspected to have inherited LSD, where the sample is collected through amniocentesis. Whereas mutation analysis is carried out for patients suspected to have inherited the disease from carriers in their family.

Treating LSD patient is a challenging task due to restriction in treatment methods and also the symptoms of LSD have adverse effects on overall body system. Most of the LSD patients are treated by managing symptoms. The few treatment methods available for specific Lysosomal storage disorder are Bone marrow transplantation, enzyme replacement therapy, substrate reduction therapy, Umbilical cord blood transplant, Gene therapy and chaperone therapy.

Bone marrow transplant involves transplanting stem cells from a healthy donor to the patient to stimulate the production of the deficient enzyme. In enzyme replacement therapy, the genetically engineered copy of the deficient enzyme is given to the patient intravenously. The rate of production of substrate responsible for the disorder is slowed by administering drugs in substrate reduction therapy. Though these methods prove to be considered treatment methods for LSD each of it has its own limitations which led to the development of research in the field of various treatment methods.

As a result the developed methods are enzyme enhancement therapy, substrate synthesis inhibition therapy, gene therapy and chaperone therapy. In enzyme enhancement therapy, the defective enzymes in LSD are stabilized and in substrate synthesis inhibition therapy applies the principle of blocking a step in substrate production thus reducing the accumulation. Gene therapy, as the name indicates the normal copy of gene replaces the mutated gene responsible for deficit enzyme, thus inducing the normal production and function of the enzyme.

Inspite of the availability of various treatment methods and diverse research to derive suitable treatment methods, the success of it depends on the condition of the patient. While treating a patient for LSD, all the other ailments, past history etc has to be taken into consideration. A complete clinical history of the patient has to be maintained and it also involves care from multidisciplinaries to treat a patient for Lysosomal storage disorder because of its complexity.

Thus the cause, symptom, diagnosis and available treatment methods for LSD is discussed. All the available treatment methods are costly and hence the earlier the diagnosis of the disease increases the maximum chances of survival from the available treatment methods. The knowledge on LSD is significant for individual and medical specialist to diagnose the disease early and treat it.