Abstract
Joubert syndrome is a group of rare disorders that stem from defects in a sensory organelle, the primary cilia. Affected patients often present with disorders involving multiple organ systems, including the brain, eyes, and kidneys. Common symptoms include breathing abnormalities, mental developmental delays, loss of voluntary muscle coordination, and abnormal eye movements, with a diagnostic “molar tooth” sign observed by magnetic resonance imaging (MRI) of the midbrain. We reviewed the ocular phenotypes that can be found in patients with Joubert syndrome. Ocular motor apraxia is the most frequent (80% of patients), followed by strabismus (74%) and nystagmus (72%). A minority of patients also present with ptosis (43%), chorioretinal coloboma (30%), and optic nerve atrophy (22%). Although mutations in 34 genes have been found to be associated with Joubert syndrome, retinal degeneration has been reported in only 38% of patients. Mutations in AHI1 and CEP290, genes critical to primary cilia function, have been linked to retinal degeneration. In conclusion, Joubert syndrome is a rare pleiotropic group of disorders with variable ocular presentations.
Highlights
Joubert Syndrome (JS) is a rare, autosomal recessive disorder with findings of episodic hyperpnea, global developmental delays, ataxia, and abnormal eye movements first described by Marie Joubert in 1969 [1,2,3]
It is accompanied by a congenital malformation of the brainstem and cerebellar vermis that composes the pathognomonic finding of a “molar tooth sign” (MTS) on magnetic resonance imaging (MRI) of the brain (Figure 1A)
Patients with JS with ocular defects (JS-O) suffer from retinal dystrophy that varies in progression and severity in addition to the abnormalities of the classic form; AHI1 mutations are frequent in this subgroup [4]
Summary
Joubert Syndrome (JS) is a rare, autosomal recessive disorder with findings of episodic hyperpnea, global developmental delays, ataxia, and abnormal eye movements first described by Marie Joubert in 1969 [1,2,3]. Additional abnormalities that may be associated with JS include renal disease, occipital encephalocele, polydactyly, ocular colobomas, retinal dystrophy, hepatic fibrosis, oral hamartomas, and endocrine disorders [4]. Patients with JS with ocular defects (JS-O) suffer from retinal dystrophy that varies in progression and severity in addition to the abnormalities of the classic form; AHI1 mutations are frequent in this subgroup [4]. Patients with JS with renal disease (JS-R) exhibit the features of a kidney disorder that is predominantly juvenile nephronophthisis (NPH), without defects in the retina; mutations of NPHP1 and RPGRIP1L are associated with this phenotype. Hypothalamic hamartoma may occur, and the pituitary gland may be absent This presentation is associated with mutations in the TMEM216 gene [5]. The number of genes associated with JS continues to increase, along with greater recognition of the importance of cilia function in the development of multiple organ systems
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
