Identification of GBA Gene Mutations in 19 Pakistani Unrelated Patients of Gaucher Disease

Introduction: Gaucher disease (GD) is one of the lysosomal storage diseases that is rare and inherited autosomal recessively. There is insufficiency of glucocerebrosidase enzyme that leads to the build up of un-degraded substrates in white blood cells causing anemia, hepatosplenomegaly and skeletal disease. This enzyme deficiency is linked with the defect of its gene (GBA) that codes for this enzyme. Initial diagnosis is made by the estimation of glucocerebrosidase level in blood and confirmed by genetic analysis of GBA gene. To identify the mutations of GBA gene in Pakistani patients with GD from different regions of Pakistan.

Sampling & methodology: The sample and demographic data was collected in National Institute of Blood Disease and Bone marrow Transplantation after approval of IRB and written informed consent of patients. We collected total 19 blood samples, out of which 5 had Gaucher's disease, 10 samples were parents of the index cases and 4 were control. The methodology consisted of DNA extraction and quantification from peripheral blood. Genetic analysis of coding regions of GBA gene was done via gene amplification, gel electrophoresis and sequencing.

Result: Mutation was found in two out of five families that makes the prevalence of GBA gene mutation 40%. These were diagnosed on reduced enzyme levels and found to have L444P (c.1448T>C) mutation in homozygous form in 10^th exon of GBA gene. The parents of that patient carried the same mutation in one allele. Rest of the patients who were diagnosed on bone marrow morphology showed no mutation in GBA gene.

Conclusion: Our results illustrate that GBA gene mutation was found in those patients who were diagnosed by the estimation of β-glucosidase enzyme levels rather than on bone marrow morphology. In our population, the mutation L444P was found, which is the most frequent gene mutation found in the world. Since this study is conducted in a small number of patients therefore it is recommended that large cohorts of patients should be evaluated in future for genetic mutations among Gaucher's patients in Pakistan

Key words: Gaucher disease, storage disorder, GBA gene