[Genetic analysis (PKD2) of autosomal dominant polycystic kidney disease]

Autosomal dominant polycystic kidney disease is a multi-organic hereditary disorder. It is responsible for 7-10% of cases of end stage renal failure. It is caused by mutations in the genes PKD1 and PKD2. Both polycystic kidney disease's forms have a pathogeny and similar clinic, but in the patients with mutation in PKD2, the clinical manifestations appear later and the progression to end stage renal failure happens 10 years later than in the patients with mutation in PKD1. The diagnosis of this disease can be performed through ultrasounds, but the molecular diagnosis offers some advantages, such as the early detection of asymptomatic individuals who carry this genetic defect, in order to perform a preventive monitoring and genetic counselling. In this work, we present the results of the mutational analysis of the PKD2 gene in 18 patients diagnosed with autosomal dominant polycystic kidney disease. The objectives of this work were to analyze the profitability of the genetic study compared with the radiologic study, and perform an early genetic diagnosis in the descendants of patients who were affected by a mutation in the PKD2 gene, trying to establish a correlation between phenotype and genotype. After the genetic analysis, only one family was diagnosed with a mutation in exon 13 of the PKD2 gene (5.56%), which consists on a substitution of the nucleotide adenosine by cytosine (c.2398A>C), which implies that the amino acid methionine is replaced by leucine (p.800Met>Leu). In our population, contrary to what was published in the literature, the mutation of the gene was clinically significant and did segregate with the disease. All the members with a clinical and ultrasound diagnosis of polycystic renal disease presented the above mentioned mutation. We could not confirm any clinical-genetic correlation. Due to the high prevalence of chronic renal failure and terminal chronic renal failure secondary to polycystic kidney disease in our study, an early genetic diagnosis would involve a better prognosis in connection with a closer clinical monitoring.