Lack of NPHP2 mutations in a newborn infant with Joubert syndrome-related disorder presenting as end-stage renal disease.

A newborn infant with end-stage renal disease (ESRD) due to nephronophthisis (NPHP) developed episodes of tachypnea, alternating with apnea, and abnormal eye movements. Contrast-enhanced magnetic resonance imaging (MRI) of the midbrain demonstrated the characteristic appearance of molar tooth sign on axial images, consistent with the diagnosis of Joubert syndrome (JBTS). The DNA sequence analysis of the polymerase chain reaction (PCR) detected no mutations in the NPHP2 (INVS) gene in this child, suggesting that new mutant genes might be responsible for the early onset of ESRD in infantile NPHP with features of JBTS.