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

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. . 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 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. Mutations in lead to multisystem ciliopathy syndromes and molecular genetic diagnostics of such cases allows precise diagnosis, screening of at risk relatives and appropriate management.