Novel Pathogenic Biallelic Variants in <scp><i>KIAA0586</i></scp> Expand the Variant Spectrum of Ciliopathies

Joubert syndrome (JBTS) is a group of recessive neurodevelopmental disorders classified as a specific type of ciliopathy with genetic heterogeneity. JBTS23, a subtype of Joubert syndrome, is caused by variations in the KIAA0586 gene. In this study, we report a 9-month-old boy diagnosed with JBTS based on the presence of the molar tooth sign in the midbrain and global developmental delay. Whole-exome sequencing identified two pathogenic variants in KIAA0586 (c.3944 T>G and c.3686 + 3A>G), consistent with an autosomal recessive inheritance pattern. These findings were confirmed through Sanger sequencing of the proband and his parents. This study identifies two novel pathogenic variants in KIAA0586, provides a genetic diagnosis for this patient as JBTS23, and expands the variant spectrum of KIAA0586 associated with JBTS.