Case Report: Identification of likely recurrent CEP290 mutation in a child with Joubert syndrome and cerebello-retinal-renal features.

Background. Joubert syndrome (JS) is a rare autosomal recessive ciliopathy with an estimated prevalence of 1 in 100,000. JS is characterized by hyperpnoea, hypotonia, ataxia, developmental delay and various neuropathological abnormalities in the brain including cerebellar hypoplasia and cerebellar vermis aplasia. JS can also have variable multi-organ involvement, including the retina, kidneys, liver, and musculoskeletal system. Methods and Results. Here we report a clinical description of two-year-old girl presenting with breathing difficulties, hyperechoic kidneys with loss of corticomedullary differentiation. Brain magnetic resonance imaging revealed the typical molar tooth sign consistent with a clinical diagnosis of JS and retinal examination showed severe retinal dystrophy leading to blindness. Molecular genetic analysis using whole exome sequencing and Sanger sequence confirmation demonstrated a homozygous mutation (c.5493delA, p.(A1832fs*19) in CEP290 which segregated from either parent and was consistent with the multisystem ciliopathy phenotype. This precise variant has been described previously in 2 families from the Kosovar-Albanian region suggesting this allele is a recurrent mutation in this population. Conclusions. Mutations in CEP290 lead to multisystem ciliopathy syndromes and molecular genetic diagnostics of such cases allows precise diagnosis, screening of at risk relatives and appropriate management.