Lysosomal storage disorders: molecular basis and laboratory testing.

Area of Science:

• Biochemistry
• Genetics
• Molecular Biology

Background:

• Lysosomal storage disorders (LSDs) encompass over 50 inherited metabolic diseases.
• Defective lysosomal enzyme function or related protein defects cause metabolite accumulation, leading to multi-systemic pathology.
• Clinical presentation of LSDs varies widely, from severe early-onset to mild late-onset phenotypes.

Purpose of the Study:

• To outline the diagnostic approaches for LSDs, emphasizing the complementary roles of biochemical and molecular genetic testing.
• To highlight the importance of genetic counseling and prenatal diagnosis in managing LSDs.

Main Methods:

• Clinical and paraclinical evaluation, including urinary metabolite analysis.
• Biochemical genetic testing (BGT) for specific enzymatic deficiencies.
• Molecular genetic testing (MGT) to refine diagnoses, identify non-enzymatic defects, and confirm genotypes for prenatal diagnosis.

Main Results:

• BGT is the primary diagnostic method for most LSDs, detecting enzymatic deficiencies.
• MGT complements BGT, refining diagnoses, identifying genetic disorders from non-enzymatic protein defects, and aiding in cases of enzymatic pseudodeficiencies.
• Prenatal diagnosis utilizes BGT and/or MGT on chorionic villus or amniotic fluid samples, requiring known family index case genotypes for MGT.

Conclusions:

• BGT and MGT are largely complementary for both post- and prenatal diagnosis of LSDs.
• Accurate diagnosis through combined testing enhances reliability in genetic counseling, prognosis, and therapeutic decisions.
• Understanding genotype-phenotype correlations is crucial for predicting disease course and guiding treatment strategies.