Is aRHGEF9 disruption in a female patient associated with X linked mental retardation and sensory hyperarousal?
ARHGEF9 encodes a RhoGEF family protein: collybistin (hPEM), which is highly expressed in the developing and adult brain. Collybistin can regulate actin cytoskeletal dynamics and may also modulate GABAergic and glycinergic neurotransmission through binding of a scaffolding protein, gephyrin, at the synapse. This potential dual role may explain both the mental retardation and hyperarousal observed in our patient. While ARHGEF9 appears to be an uncommon cause of mental retardation in males, it should be considered in patients with mental retardation and sensory hyperarousal.
Our study suggests that PD patients with dementia are two times more likely to have insulin resistance than patients with PD.