The Genomic Landscape of Rare Disorders in the Middle East

Abstract

BACKGROUNDRare diseases collectively impose significant burden on healthcare systems, especially in underserved regions, like the Middle East, which lack access to genomic diagnostic services and the associated personalized management plans. METHODSWe established a clinical genomics and genetic counselling facility, within a multidisciplinary tertiary paediatric center, in the United Arab Emirates to locally diagnose and manage patients with rare diseases. Clinical genomic investigations included exome-based sequencing, chromosomal microarrays, and/or targeted testing. We assessed the diagnostic yield and implications for clinical management among this population. RESULTSWe present data on 529 patients with rare diseases (47% females; Average age, 4 years) representing 41 countries primarily from the Arabian Peninsula, the Levant, Africa, and Asia. The cumulative diagnostic yield was 35.7% (95% CI, 31.8% - 39.9%) and was higher for genomic sequencing-based testing than chromosomal microarrays (41.2% versus 16.9%, P=0.0001) across all indications, consistent with the higher burden of single gene disorders. Of the 124 Mendelian disorders identified in this cohort, the majority (N = 110) were encountered only once, and those with recessive inheritance accounted for ~60% of sequencing diagnoses. Of patients with positive genetic findings (N = 189), 71.9% were less than 5 years of age, and 65.6% were offered modified management and/or intervention plans. Interestingly, 18.5% of patients with positive genetic findings received delayed diagnoses (age range 7 - 37 years), most likely due to lack of access to genomic investigations in this region. One such genetic finding ended over a 10-year long diagnostic odyssey, leading to a life-threatening diagnosis in one patient, who was then successfully treated using an experimental allogenic bone marrow transplant. Finally, we present cases with candidate genes within regions of homozygosity, likely underlying novel recessive disorders. CONCLUSIONSEarly access to genomic diagnostics for patients with suspected rare disorders in the Middle East is likely to improve clinical outcomes while driving gene discovery in this historically underrepresented population.