Pearson syndrome

Pearson syndrome is a specific clinical subset of mitochondropathy  syndromes with prominent involvement of the bone marrow and exocrine pancreas The first defining feature is marrow failure with macrocytic sideroblastic anaemia and characteristic vacuolation of haematopoietic precursors. The anaemia is refractory, and patients may be transfusion dependent. Neutropenia and thrombocytopenia also may be present. The second defining feature of Pearson syndrome is dysfunction of the exocrine pancreas due to fibrosis and acinar atrophy. This results in malabsorption and chronic diarrhea. Another cardinal feature of Pearson syndrome is persistent or intermittent lactic acidemia, which is caused by a defect in oxidative phosphorylation. Other organ systems are affected in various ways. Hepatic involvement may cause increases in transaminases, hyperbilirubinemia, hyperlipidemia, and steatosis. Some patients develop hepatic failure. Renal involvement is common and manifests as a tubulopathy such as Fanconi syndrome. Endocrinologic disturbances such as growth hormone deficiency, hypothyroidism, and hypoparathyroidism are less common. The endocrine pancreas usually remains functional; however, a few patients develop diabetes mellitus. Splenic atrophy and impaired cardiac function have also been reported.