[Joubert syndrome and related disorders]

Area of Science:

• Neuroscience
• Genetics
• Developmental Biology

Background:

• The cerebellum is crucial for motor control, learning, and cognition.
• Joubert syndrome (JSRD) is a rare inherited genetic disorder affecting the cerebellum, characterized by ataxia, hypotonia, developmental delay, and specific neurological features.
• JSRD is considered a ciliopathy, a group of disorders related to defects in cilia function.

Purpose of the Study:

• To review the clinical presentation of Joubert syndrome and related disorders (JSRD).
• To discuss the differential diagnosis for JSRD.
• To elucidate the molecular genetic background of JSRD.

Main Methods:

• Literature review focusing on clinical and genetic aspects of JSRD.
• Analysis of neuroimaging findings, particularly the "molar tooth sign" associated with JSRD.
• Review of identified causal genes and their role in the pathogenesis of JSRD.

Main Results:

• JSRD presents with a spectrum of clinical features including ataxia, hypotonia, and developmental delay.
• The "molar tooth sign" on brain neuroimaging is a key diagnostic feature for JSRD.
• Identification of seven causal genes (NPHP1, AHI1, CEP290, RPGRIP1L, TMEM67/MKS3, ARL13B, CC2D2A) has significantly advanced understanding of JSRD genetics.

Conclusions:

• Joubert syndrome and related disorders represent a significant group of ciliopathies with diverse clinical manifestations.
• Understanding the genetic basis is key to diagnosing and potentially treating JSRD.
• Further research into the identified genes will enhance knowledge of JSRD pathogenesis and therapeutic strategies.