Advances in Diagnosis of Mitochondrial Diseases: Case Report of an Infant with Pearson Syndrome

Abstract

Pearson syndrome (PS) is a mitochondrial disorder that presents in early infancy as a multisystemic disease affecting the bone marrow and pancreas. It may present with anemia, diarrhea, exocrine pancreatic dysfunction, and failure to thrive.[1] Delay in diagnosis can lead to severe morbidity and mortality in infancy. We report the case of a 9-month-old presenting with failure to thrive, severe macrocytic anemia and pancytopenia initially thought to have gastroesophageal reflux and feeding intolerance. Severe macrocytic anemia and pancytopenia prompted an early bone marrow evaluation. Abnormal bone marrow findings including vacuolated marrow precursors and ringed sideroblasts along with persistent mild lactic acidosis led to a rapid and extensive genetics workup. Whole exome sequencing including mitochondrial genome sequencing detected a 2.3 kb heteroplasmic deletion in m.12113_14421 encompassing the MT-ND5 gene consistent with the diagnosis of Pearson Syndrome. This case report highlights the advances in molecular genetic testing to diagnose patients with complex medical histories along the spectrum of mitochondrial diseases and the importance of early diagnosis to start treatment.