A case of Pearson syndrome confirmed by mitochondrial genetic tests

Abstract

Mitochondrial DNA (mtDNA) mutations and deletions are important causes of inherited mitochondrial diseases. The clinical manifestations of mtDNA disorders are extremely variable. Thus, we comprehensively determine mitochondrial diseases from the results of not only genetic tests but also image examination, histological examination, and clinical examination. In this report, we describe the case of a 1.5-year-old infant with exocrine gland disturbances and diarrhea. As blood tests showed high pyruvic acid and lactic acid levels in the plasma, mitochondrial disease was suspected. We detected no base substitution and minor deletion in the peripheral blood sample by the direct sequencing of PCR (polymerase chain reaction) products. Following long-distance PCR amplification to detect total mtDNA, a large-scale mtDNA deletion was detected in this patient. Sanger sequencing identified the breakpoints of the 5 kb deletion. Southern blot analysis confirmed that the deletion ratio of mtDNA is 33% in peripheral blood and 51% in a bone marrow sample. After molecular analysis of mtDNA and extensive clinical investigation, the patient was diagnosed as having Pearson syndrome, and we confirmed the usefulness of mitochondrial genetic tests.