Molecular genetic studies of inherited cystic kidney disease in Oman

Abstract

Inherited kidney diseases are fundamental causes of chronic kidney disease (CKD) and end stage kidney disease (ESKD); accounting for approximately 20% of all CKD cases and up to 10% of adults and over 70% of children reaching ESKD. Oman is the second largest country in the South East of Arabian Peninsula. Omani population is characterized by large family size, presence of tribal and geographical settlements and higher rates of consanguineous marriages, which facilitate the study of autosomal recessive disorders. Rare genetic disorders create considerable burden on healthcare system in Oman and are major causes of congenital abnormalities and perinatal deaths in hospitals. The prevalence of inherited kidney disease was estimated to be high, but there is a lack for a comprehensive data. Therefore, this study aimed to evaluate the magnitude of inherited kidney disease in this population and identify the molecular genetic causes of inherited cystic kidney diseases in Omani patients. First, I performed a population-based retrospective analysis of ESKD patients commencing RRT from 2001 to 2015 using the national renal replacement therapy (RRT) registry and evaluated the epidemiological and etiological causes of ESKD with focused attention on inherited kidney diseases. Second, I designed a targeted gene panel (49 genes) and used massive parallel sequencing technologies for the molecular genetic diagnosis of cystic kidney disease in 53 patients. An overall molecular genetic diagnostic yield of 75% was achieved; with 46% of detected causative variants were novel genetic findings. Third, I evaluated the utility of molecular genetic testing in patients with autosomal recessive polycystic kidney disease (ARPKD) and described the clinical and genetic profile of this cohort. Finally, whole exome sequencing (WES) was used to determine the genetic causes of CKD in 11 unrelated children suspected with recessively inherited kidney diseases. Definite genetic diagnosis was achieved in 54.5% of cases, reflecting the importance of genomic implications in those with uncertain aetiology causing CKD. This study creates a solid basis reflecting the genotype-phenotype of some inherited kidney diseases in Omani population and reveals the enormous diagnostic power of genomic technologies.