When Dr. Bodo Beck first saw the three children of a family who had fled Syria sitting in his consultation room at University Hospital Cologne, the human geneticist was surprised. His genetic analysis diagnosed Bartter syndrome type 3, but never before had he seen such severe joint changes in patients with this rare disease. The kidney disease is hereditary – affected individuals lack the CLCNKB gene, which is responsible for a specific chloride channel. The electrolyte balance becomes disrupted because the kidneys cannot reabsorb important nutrients and salts back into the bloodstream during filtration and urine production. In addition to the absence of the CLCNKB gene, Dr. Beck suspected there might be more extensive deletions – areas completely eliminated from the genome--that would explain the severe clinical picture. To find this out would require taking a closer look at the disease-causing genes, so he contacted Dr. Janine Altmüller, Head of the Genomics Platform of the Max Delbrück Center and the Berlin Institute of Health at Charité (BIH). Her team, which is based at the Berlin Institute for Medical Systems Biology of the Max Delbrück Center (MDC-BIMSB), has pioneered cutting-edge sequencing technologies like long-read sequencing. This technology enabled them to analyze parts of patients’ genomes that could not previously be resolved. They have now published their findings on August 23, 2023 in the journal Genome Medicine. The open-access article is titled “Long-Read Sequencing Identifies a Common Transposition Haplotype Predisposing for CLCNKB Deletions.”