Proline-rich transmembrane protein 2 knock-in mice present dopamine-dependent motor deficits

Mutations of proline-rich transmembrane protein 2 (PRRT2) lead to dyskinetic disorders such as paroxysmal kinesigenic dyskinesia (PKD), which is characterized by attacks of involuntary movements precipitated by suddenly initiated motion, and some convulsive disorders. Although previous studies have shown that PKD might be caused by cerebellar dysfunction, PRRT2 has not been sufficiently analyzed in some motor-related regions, including the basal ganglia, where dopaminergic neurons are most abundant in the brain. Here, we generated several types of Prrt2 knock-in (KI) mice harboring mutations, such as c.672dupG, that mimics the human pathological mutation c.649dupC and investigated the contribution of Prrt2 to dopaminergic regulation. Regardless of differences in the frameshift sites, all truncating mutations abolished Prrt2 expression within the striatum and cerebral cortex, consistent with previous reports of similar Prrt2 mutant rodents, confirming the loss-of-function nature of these mutations. Importantly, administration of l-dopa, a precursor of dopamine, exacerbated rotarod performance, especially in Prrt2-KI mice. These findings suggest that dopaminergic dysfunction in the brain by the PRRT2 mutation might be implicated in a part of motor symptoms of PKD and related disorders.

[A case of spontaneous biloma accompanied with incarcerated choledocholithiasis]

A 55-year-old man was admitted with abdominal pain and nausea. CT-scan and US showed no abnormal findings. On the 5th hospital day, a large mass was palpable on the upper abdomen, and CT-scan (7th hospital day) demonstrated a large, cystic mass below the left lobe. A thoracentesis under ultrasound guidance obtained bile-stained fluid. PTCD revealed choledocholithiasis and severe dilatation of the common bile duct and the left branch. After conservative treatment, cholecystectomy and choledocholithotomy were performed. Biloma occurred mainly traumatically or iatrogenically. This case had a spontaneous biloma, and only 11 cases have been previously reported as spontaneous biloma in Japan.