Pearson syndrome: a rare inborn error of metabolism with bone marrow morphology providing a clue to diagnosis

Hematologic Manifestations in Primary Mitochondrial Diseases

Primary mitochondrial disorders (PMDs) are known for their pleiotropic manifestations in humans, affecting almost any organ or system at any time. Hematologic manifestations, such as cytopenias and sideroblastic anemia, occur in 10% to 30% of patients with confirmed PMDs. These can be the initial presenting features or complications that develop over time. Surveillance for these manifestations allows for prompt identification and treatment. This article provides an overview of the pathophysiology underpinning the hematologic effects of mitochondrial dysfunction, discussing the 3 key roles of the mitochondria in hematopoiesis: providing energy for cell differentiation and function, synthesizing heme, and generating iron-sulfur clusters. Subsequently, the diagnosis and management of mitochondrial disorders are discussed, focusing on hematologic manifestations and the specific conditions commonly associated with them. Through this, we aimed to provide a concise point of reference for those considering a mitochondrial cause for a patient's hematologic abnormality, or for those considering a hematologic manifestation in a patient with known or suspected mitochondrial disease.

Mitochondrial Chronic Progressive External Ophthalmoplegia

BACKGROUND

Chronic progressive external ophthalmoplegia (CPEO) is a rare disorder that can be at the forefront of several mitochondrial diseases. This review overviews mitochondrial CPEO encephalomyopathies to enhance accurate recognition and diagnosis for proper management.

METHODS

This study is conducted based on publications and guidelines obtained by selective review in PubMed. Randomized, double-blind, placebo-controlled trials, Cochrane reviews, and literature meta-analyses were particularly sought.

DISCUSSION

CPEO is a common presentation of mitochondrial encephalomyopathies, which can result from alterations in mitochondrial or nuclear DNA. Genetic sequencing is the gold standard for diagnosing mitochondrial encephalomyopathies, preceded by non-invasive tests such as fibroblast growth factor-21 and growth differentiation factor-15. More invasive options include a muscle biopsy, which can be carried out after uncertain diagnostic testing. No definitive treatment option is available for mitochondrial diseases, and management is mainly focused on lifestyle risk modification and supplementation to reduce mitochondrial load and symptomatic relief, such as ptosis repair in the case of CPEO. Nevertheless, various clinical trials and endeavors are still at large for achieving beneficial therapeutic outcomes for mitochondrial encephalomyopathies.

KEY MESSAGES

Understanding the varying presentations and genetic aspects of mitochondrial CPEO is crucial for accurate diagnosis and management.

A Case Report on Pearson Syndrome With Emphasis on Genetic Screening in Patients Presenting With Sideroblastic Anemia and Lactic Acidosis

Pearson marrow-pancreas syndrome is a rare multisystem mitochondrial disease that is a result of defective oxidative phosphorylation caused by mitochondrial DNA mutations. The average prognosis of infants diagnosed with this disease is death within four years of age. The disease often carries an atypical presentation during the neonatal period causing this rare syndrome to be frequently misdiagnosed. The current report details the diagnosis of Pearson syndrome in a three-month-old male with a history of pancytopenia.

Preterm twins with antenatal presentation of Pearson syndrome

Objectives

Pearson syndrome is a mitochondrial cytopathy with multisystemic involvement that typically presents in infancy and has poor prognosis. We aim to present a case that is distinct due to the timing of presentation and associated anomalies.

Case presentation

We report the case of preterm monochorionic twins with transfusion dependent fetal anemia that had post-natal multisystem dysfunction which led to the diagnosis of Pearson syndrome.

Conclusions

This case highlights the possibility of antenatal presentation of Pearson syndrome, which should be considered in cases of severe fetal anemia without an apparent cause.

Lactic Acidosis in a Congenital Bone Marrow Failure Syndrome

Fifteen-month-old male child, known to have a congenital bone marrow failure syndrome, presented in a state of shock with severe lactic acidosis following a brief episode of vomiting. Hospital stay was complicated by recurrent bouts of metabolic acidosis and progressive hepatic failure. Blood mitochondrial DNA sequencing revealed a large heteroplasmic 4,977 bp mitochondrial deletion (approximately 40% of all mitochondrial copies) suggestive of Pearson marrow-pancreas syndrome. By virtue of natural disease course, within a month of admission child succumbed to end-stage liver failure with multi-organ failure and died.