Pearson Syndrome is classified as a mitochondrial disease because it consists of several overlapping syndromes that are caused by mutations of mitochondrial DNA. Specifically, Pearson Syndrome is a combination of syndromes that involves the bone marrow and the exocrine pancreas.t is usually fatal in infancy. The few patients who survive into adulthood often develop symptoms of Kearns-Sayre syndrome. It is caused by a deletion in mitochondrial DNA. Pearson syndrome is very rare, less than hundred cases have been reported in medical literature worldwide.