Prevalence of Gaucher Disease in Patients of Unknown Cause of Splenomegaly and/or Thrombocytopenia in Saudi Arabia

Rationale: Gaucher disease (GD) is the most common amongst the lysosomal storage disorders. Prevalence of GD in Saudi Arabia is not available in published literature and it is expected to be high and remains undiagnosed. In 2004, a Saudi study reported that GD accounts for 6% of all genetic metabolic disorders. While acid sphingomyelinase deficiency (ASMD) is a rare progressive genetic disorder with no clear data about its incidence in Saudi Arabia. Consequently, this study proposes to determine the prevalence of GD and ASMD in outpatient settings in Saudi Arabia by screening patients with unknown causes of splenomegaly and/or thrombocytopenia. These data will change the local practice and increase the awareness towards GD and ASMD in Saudi Arabia.

Objectives: To determine the prevalence of GD in high risk group (defined as patients with splenomegaly and/or thrombocytopenia of unknown cause) and describe their characteristics. We also aim to determine the prevalence of ASMD in high risk group.

Methods: A multi-center, observational, study will be conducted in 25 specialty care centres across Saudi Arabia, these centres are mainly focusing on pediatric hematology, adult hematology and hemato-pathology. Female or male patients (aged 2-75 years) will deemed eligible if they have clinical, instrumental or laboratory signs of splenomegaly or thrombocytopenia over a period of 12 months without definitive cause. These patients will be tested for acid β-glucosidase and acid sphingomyelinase enzymes activity on dried blood spot (DBS) samples. Patients with hematological malignancies, hemolytic anemia, and/or thalassemia (except sickle cell disease) will be excluded. A total of 400 patients from Saudi Arabia who fulfill the eligibility criteria will be enrolled in the study. All patient data will be collected in a single visit. Each enrolled patient will visit the investigator for a baseline visit. The investigator will contact them later for sharing the investigation blood test results. During the baseline visit, data and blood sample for enzyme tests and genotyping will be collected by the investigator/designated person at the site.

Discussion: Arab world represents one of the leading regions in terms of the incidence of congenital and genetic disorders; a growing body of published literature reported a notable trends towards higher incidence of congenital and genetic diseases, compared to other parts of the world(1). High consanguinity rates which reach up to 60% in some regions, high prevalence of haemoglobinopathies and metabolic disorders, relatively high maternal and parental age, and lack of proper genetic screening were reported as contributing factors for this high prevalence of genetic disorders in the Arab world(1-3). In Saudi Arabia, the situation appears to be no different as previous retrospective studies showed a relatively high incidence of genetic diseases such as inborn error of metabolism. The data of the present study will change the local practice and increase the awareness towards GD and ASMD in Saudi Arabia.

References:

1. Al-Gazali L, Hamamy H, Al-Arrayad S. Genetic disorders in the Arab world. BMJ [Internet]. 2006 Oct 21 [cited 2019 Jun 29];333(7573):831-4. Available from: http://www.ncbi.nlm.nih.gov/pubmed/17053236

2. Al-Gazali LI, Alwash R, Abdulrazzaq YM. United Arab Emirates: Communities and Community Genetics. Public Health Genomics [Internet]. 2005 [cited 2019 Jun 29];8(3):186-96. Available from: http://www.ncbi.nlm.nih.gov/pubmed/16113536

3. Wahab AA, Bener A, Teebi AS. The incidence patterns of Down syndrome in Qatar. Clin Genet [Internet]. 2006 Mar 30 [cited 2019 Jun 29];69(4):360-2. Available from: http://www.ncbi.nlm.nih.gov/pubmed/16630172