Something to sink your teeth into.

Area of Science:

• Genetics
• Neurology
• Ophthalmology

Background:

• Joubert syndrome is a rare genetic disorder typically diagnosed in childhood, characterized by specific brain abnormalities and developmental delays.
• The classic triad includes cerebellar vermis hypoplasia, brainstem malformation (often with a "molar tooth" sign), and episodic tachypnea or apnea.
• While often presenting in infancy, atypical or later-onset presentations can occur, complicating diagnosis.

Observation:

• A 21-year-old Kuwaiti male presented with cerebral palsy, retinitis pigmentosa, hypertension, and renal failure.
• Ocular motility examination revealed aperiodic alternating skew deviation in the patient and his affected siblings.
• Neuroimaging demonstrated superior cerebellar vermis hypoplasia with the characteristic "molar tooth" sign.

Findings:

• Genetic analysis identified a mutation in the AHPI gene on chromosome 6p23.3 in the affected siblings, confirming Joubert syndrome.
• The patient's constellation of symptoms, including retinitis pigmentosa and alternating skew deviation, are recognized, albeit less common, features of Joubert syndrome.
• This familial case underscores the phenotypic variability of Joubert syndrome, extending into adulthood.

Implications:

• The diagnosis of Joubert syndrome should be considered in adults presenting with retinitis pigmentosa, especially when accompanied by other neurological or systemic findings.
• Familial alternating skew deviation can be a key indicator for Joubert syndrome in the absence of more typical early childhood signs.
• Identifying genetic mutations like AHPI is crucial for accurate diagnosis, genetic counseling, and understanding the broader spectrum of Joubert syndrome.