Genetic kidney diseases as an underrecognized cause of chronic kidney disease : the key role of international registry reports

Inherited kidney diseases (IKDs) are among the leading causes of early-onset chronic kidney disease (CKD) and are responsible for at least 10-15% of cases of kidney replacement therapy (KRT) in adults. Paediatric nephrologists are very aware of the high prevalence of IKDs among their patients, but this is not the case for adult nephrologists. Recent publications have demonstrated that monogenic diseases account for a significant percentage of adult cases of CKD. A substantial number of these patients have received a non-specific/incorrect diagnosis or a diagnosis of CKD of unknown aetiology, which precludes correct treatment, follow-up and genetic counselling. There are a number of reasons why genetic kidney diseases are difficult to diagnose in adulthood: (i) adult nephrologists, in general, are not knowledgeable about IKDs; (ii) existence of atypical phenotypes; (iii) genetic testing is not universally available; (iv) family history is not always available or may be negative; (v) lack of knowledge of various genotype-phenotype relationships and (vi) conflicting interpretation of the pathogenicity of many sequence variants. Registries can contribute to visualize the burden of IKDs by regularly grouping all IKDs in their annual reports, as is done for glomerulonephritis or interstitial diseases, rather than reporting only cystic disease and hiding other IKDs under labels such as 'miscellaneous' or 'other'. Any effort to reduce the percentage of patients needing KRT with a diagnosis of 'nephropathy of unknown etiology' or an unspecific/incorrect diagnosis should be encouraged as a step towards precision nephrology. Genetic testing may be of value in this context but should not be used indiscriminately, but rather on the basis of a deep knowledge of IKDs