Lekárska genetika a diagnostika 1/2026
First reported case of Pearson syndrome in Slovakia with atypical phenotype of short stature and mesomelia
In this case report, we describe a patient with Pearson syndrome, representing the first published case of this rare disorder in Slovakia. The 18-month-old male patient presented with symptoms including short stature, failure to thrive, pancytopenia, comprising macrocytic anemia, neutropenia, and thrombocytopenia. The clinical manifestations also included pancreatic insufficiency, hepatopathy and delayed psychomotor development. In addition to typical features of Pearson syndrome, the patient exhibited atypical manifestations, such as mesomelia and dysmorphic facial features, which contributed to consider other diagnosis firstly. Based on the clinical phenotype, the patient was referred for whole exome sequencing (WES), with primary virtual gene panels focused on inborn errors of immunity and inherited anemias. WES analysis did not identify a causative variant within the initially indicated gene panels; however, a large-scale deletion of mitochondrial DNA (mtDNA), m.10952_15371del, was detected as a secondary finding in a heteroplasmic state (55.8% in a peripheral blood sample). Subsequent MLPA analysis confirmed the presence of this deletion in additional tissues (urine, bone marrow aspirate, and buccal swab), with the highest level of heteroplasmy (70%) observed in the urine sample. The identified deletion affects multiple mitochondrial genes, which may significantly impair the function of the mitochondrial respiratory chain and ATP production. Our study highlights the importance of a comprehensive diagnostic approach, including the analysis of multiple tissues, particularly in the evaluation of clinically complex mitochondrial disorders.
Keywords: Pearson syndrome, WES, mitochondrial DNA, heteroplasmy
