NPHP1 and kidney disorder: In 2018, a Dutch study on 5 international cohorts reported that 26 of 5606 patients (0.5%) with adult-onset ESRD showed homozygous NPHP1 deletions and were genetically diagnosed with nephronophthisis; however, only 3 (12%) were correctly diagnosed as having nephronophthisis, and the rest were misdiagnosed as having other kidney diseases or were diagnosed as having CKD with an unknown etiology.7