Tolvaptan use in a patient with TSC2 - PKD1 contiguous gene deletion syndrome – a case report

Abstract The TSC2 gene is contiguous to the PKD1 gene on chromosome 16. A large deletion in this region is associated with a clinical phenotype involving features of tuberous sclerosis and polycystic kidney disease (TSC-PKD CGD). While Tolvaptan use in patients with autosomal dominant polycystic kidney disease is well established, it is less so in those TSC-PKD CGD syndrome. Here, we report a case of Tolvaptan use in a 23 year old woman diagnosed with TSC - PKD CGD using micro-array testing. She had a known diagnosis of tuberous sclerosis, but renal imaging had shown enlarged polycystic kidneys and no angiomyolipomas. Following a rapid decline in kidney function, micro-array testing was arranged, which confirmed a large deletion involving the TSC2 and PKD 1 genes respectively. She was subsequently commenced on Tolvaptan therapy, which has been well tolerated, without significant side effects. After 12 months of therapy, the rate of decline in kidney function is slower in comparison to the pre-Tolvaptan phase.