Interestingly, a knockout mutation of the Htra2/Omi gene in mouse leads to neuromuscular changes similar to PD (176), while cellular studies revealed that HtrA2 knockout leads to mitochondrial dysfunction, accumulation of unfolded proteins, enhanced CHOP expression and increased ROS production (177), features also seen in metabolic disorders. The gene discussed is HTRA2; the disease is Parkinson disease.