patients, with NPHP1 being responsible for 20% of the genetically studied cases[13]. Nevertheless, further potential genes are expected to be discovered due to the enormous clinico-genetic (phenotype-genotype) heterogeneity of the disease that has a marked influence on its presentation and severity, and the massive phenotypic overlap that results in emerging of many syndromes [12,16]. Mutations in the IQCB1/NPHP5 (SLN5/OMIM; 609237, on chromosome 3q21) are reported to be the most frequent causes of SL syndrome [4], with a phenotypic variation between carriers of different mutations along the same gene [22,23]. We have investigated an Arab family from Kuwait having two children affected with S-L syndrome. Molecular analysis revealed a novel IQCB1/NPHP5 gene mutation that we report for the first time. Identification of the causative gene mutation confirmedthe clinical diagnosis and encouraged other family members to seek genetic counselling and testing.