Replacing a kidney biopsy by exome sequencing in undetermined kidney diseases – not yet ready for prime time!

The diagnosis of kidney diseases traditionally relies on clinical features, laboratory tests and imaging. In many cases, a kidney biopsy is necessary to determine the underlying pathology. However, kidney biopsies are invasive and carry a risk of complications such as bleeding. In some cases, a renal biopsy may not yield a definitive diagnosis. Undetermined kidney disease ( UKD ) is a relatively new term for which KDIGO has already indicated the need for further clarification, but it unequivocally refers to a group of patients that are lacking a final diagnosis in spite of various efforts to obtain one. UKD forms a challenge for nephrologists but recent studies have shown that monogenic disease-causing variants may explain around 25% of these nephropathies [ 1 ]. This editorial discusses a study published in this issue of Clinical Kidney Journal [ 2 ] that investigated the effectiveness of exome sequencing ( ES ) in getting closer to a diagnosis of patients with UKD, and the implications of this approach for routine nephrological healthcare. Inherited kidney diseases assumably account for around 10%–15% of