Loss of interruption in the HTT CAG repeat is associated with somatic expansion and loss of medium spiny neurons in Huntington's disease.

Loss of interruption in the HTT CAG repeat correlates with increased somatic expansions and significant loss of medium spiny neurons in Huntington's disease.

• Why it matters: Understanding how somatic CAG expansion impacts neuron degeneration is crucial for developing targeted therapies for HD, as it links genetic instability to disease progression.
• What they did: The study analyzed the relationship between somatic CAG expansions and MSN loss in HD patients, focusing on the effects of the CAG-CCG loss-of-interruption variant across 111-150 and >150 CAG repeats.
• The result: Findings reveal that larger somatic expansions are more common as the disease progresses and are associated with greater MSN loss, especially in patients with the LOI variant, highlighting somatic expansion's role in disease acceleration.