3-Methylglutaconic aciduria in a patient with Pearson syndrome

Case Report: Clinical and Genetic Characteristics of Pearson Syndrome in a Chinese Boy and 139 Patients

Background: Pearson’s syndrome (PS) is a rare multi-system disorder caused by mitochondrial DNA deletion. Most PS cases in the literature are individual reports, and there is a lack of systematic analysis of clinical features and gene mutations in large samples.

Objective: To report a case of PS and summarize the clinical features and genetic characteristics of PS by reviewing the literature.

Methods: We reported a case of PS in a boy with severe anemia and multi-system disorder. Genetic etiology was identified by mitochondrial DNA sequencing and whole-exon sequencing. Clinical features and gene mutations were summarized by literature review.

Results: The patient had major clinical manifestations with recurrent anemia and multiple organ failure after infection. Mitochondrial DNA sequencing revealed a de novo heteroplasmic deletion of 3.063 kb (nt 6,224–9,287) with 75% heteroplasmy in peripheral blood. A total of 139 PS cases were retrieved after a literature search. The most common initial symptom was refractory anemia requiring repeated blood transfusion (86.2%), digestive system symptoms (26.9%), and failure to thrive (15.4%). During the course of disease, the observed symptoms were bone marrow failure (100%), metabolic disorders (61.87%) and gastrointestinal symptoms (61.87%), failure to thrive (48.9%), renal disorders (42.45%), and pancreatic exocrine insufficiency (39.6%). The mean heteroplasmy of mitochondrial DNA mutation in peripheral blood in deaths (76.29 ± 11.86%, n = 29) was higher than that in survivals (59.92 ± 23.87%, n = 26, p < 0.01). Among the patients with the 4.977 kb deletion, the heteroplasmy in peripheral blood in deaths (79.64 ± 9.71%, n = 11) was higher than that in survivals (56.67 ± 27.65%, n = 9, p < 0.05).

Conclusion: PS can affect multiple systems, and mitochondrial DNA sequencing should be performed early. The heteroplasmy in peripheral blood is related to prognosis.

Pearson syndrome

INTRODUCTION

Pearson syndrome (PS) is a sporadic and very rare syndrome classically associated with single large-scale deletions of mitochondrial DNA and characterized by refractory sideroblastic anemia during infancy. Areas covered: This review presents an analysis and interpretation of the published data that forms the basis for our understanding of PS. PubMed, Google Scholarand Thompson ISI Web of Knowledge were searched for relevant data. Expert commentary: PS is a very rare mitochodrial disease that involves different organs and systems. Clinical phenotype is extremely variable and may change over the course of disease itself with the possibility both of worsenings and improvements. Outcome is invariably lethal and at the moment no cure is available. Accurate supportive treatment and follow up program in centres with experience in mitochondrial diseases and marrow failure may positively influence quality and duration of life.

Clinical manifestations and enzymatic activities of mitochondrial respiratory chain complexes in Pearson marrow-pancreas syndrome with 3-methylglutaconic aciduria: a case report and literature review

Pearson marrow-pancreas syndrome (PS) is a rare mitochondrial disorder. Impaired mitochondrial respiratory chain complexes (MRCC) differ among individuals and organs, which accounts for variable clinical pictures. A subset of PS patients develop 3-methylglutaconic aciduria (3-MGA-uria), but the characteristic symptoms and impaired MRCC remain unknown. Our patient, a girl, developed pancytopenia, hyperlactatemia, steatorrhea, insulin-dependent diabetes mellitus, liver dysfunction, Fanconi syndrome, and 3-MGA-uria. She died from cerebral hemorrhage at 3 years of age. We identified a novel 5.4-kbp deletion of mitochondrial DNA. The enzymatic activities of MRCC I and IV were markedly reduced in the liver and muscle and mildly reduced in skin fibroblasts and the heart. To date, urine organic acid analysis has been performed on 29 PS patients, including our case. Eight patients had 3-MGA-uria, while only one patient did not. The remaining 20 patients were not reported to have 3-MGA-uria. In this paper, we included these 20 patients as PS patients without 3-MGA-uria. PS patients with and without 3-MGA-uria have similar manifestations. Only a few studies have examined the enzymatic activities of MRCC.

CONCLUSION

No clinical characteristics distinguish between PS patients with and without 3-MGA-uria. The correlation between 3-MGA-uria and the enzymatic activities of MRCC remains to be elucidated.

WHAT IS KNOWN

• The clinical characteristics of patients with Pearson marrow-pancreas syndrome and 3-methylglutaconic aciduria remain unknown.

WHAT IS NEW

• No clinical characteristics distinguish between Pearson marrow-pancreas syndrome patients with and without 3-methylglutaconic aciduria.

Pearson Syndrome: A Retrospective Cohort Study from the Marrow Failure Study Group of A.I.E.O.P. (Associazione Italiana Emato-Oncologia Pediatrica)

Pearson syndrome (PS) is a very rare and often fatal multisystemic mitochondrial disorder involving the liver, kidney, pancreas, and hematopoietic and central nervous system. It is characterized principally by a transfusion-dependent anemia that usually improves over time, a tendency to develop severe infections, and a high mortality rate. We describe a group of 11 PS patients diagnosed in Italy in the period 1993-2014. The analysis of this reasonably sized cohort of patients contributes to the clinical profile of the disease and highlights a rough incidence of 1 case/million newborns. Furthermore, it seems that some biochemical parameters like increased serum alanine and urinary fumaric acid can help to address an early diagnosis.

3-Methylglutaconic aciduria--lessons from 50 genes and 977 patients

Elevated urinary excretion of 3-methylglutaconic acid is considered rare in patients suspected of a metabolic disorder. In 3-methylglutaconyl-CoA hydratase deficiency (mutations in AUH), it derives from leucine degradation. In all other disorders with 3-methylglutaconic aciduria the origin is unknown, yet mitochondrial dysfunction is thought to be the common denominator. We investigate the biochemical, clinical and genetic data of 388 patients referred to our centre under suspicion of a metabolic disorder showing 3-methylglutaconic aciduria in routine metabolic screening. Furthermore, we investigate 591 patients with 50 different, genetically proven, mitochondrial disorders for the presence of 3-methylglutaconic aciduria. Three percent of all urine samples of the patients referred showed 3-methylglutaconic aciduria, often in correlation with disorders not reported earlier in association with 3-methylglutaconic aciduria (e.g. organic acidurias, urea cycle disorders, haematological and neuromuscular disorders). In the patient cohort with genetically proven mitochondrial disorders 11% presented 3-methylglutaconic aciduria. It was more frequently seen in ATPase related disorders, with mitochondrial DNA depletion or deletion, but not in patients with single respiratory chain complex deficiencies. Besides, it was a consistent feature of patients with mutations in TAZ, SERAC1, OPA3, DNAJC19 and TMEM70 accounting for mitochondrial membrane related pathology. 3-methylglutaconic aciduria is found quite frequently in patients suspected of a metabolic disorder, and mitochondrial dysfunction is indeed a common denominator. It is only a discriminative feature of patients with mutations in AUH, TAZ, SERAC1, OPA3, DNAJC19 TMEM70. These conditions should therefore be referred to as inborn errors of metabolism with 3-methylglutaconic aciduria as discriminative feature.

The 3-methylglutaconic acidurias: what's new?

The heterogeneous group of 3-methylglutaconic aciduria (3-MGA-uria) syndromes includes several inborn errors of metabolism biochemically characterized by increased urinary excretion of 3-methylglutaconic acid. Five distinct types have been recognized: 3-methylglutaconic aciduria type I is an inborn error of leucine catabolism; the additional four types all affect mitochondrial function through different pathomechanisms. We provide an overview of the expanding clinical spectrum of the 3-MGA-uria types and provide the newest insights into the underlying pathomechanisms. A diagnostic approach to the patient with 3-MGA-uria is presented, and we search for the connection between urinary 3-MGA excretion and mitochondrial dysfunction.

Pearson syndrome in the neonatal period: two case reports and review of the literature

Pearson syndrome is a multiorgan mitochondrial cytopathy that results from defective oxidative phosphorylation owing to mitochondrial DNA deletions. Prognosis is severe and death occurs in infancy or early childhood. This article describes 2 cases with a severe neonatal onset of the disease. A review of the literature reveals the atypical presentation of the disease in the neonatal period, which is often overlooked and underdiagnosed.

Myeloid dysplasia in familial 3-methylglutaconic aciduria

A kindred is reported with four members affected with neurodegenerative disorder and 3-methylglutaconic aciduria. Two siblings developed thrombocytopenia heralding a myelodysplastic syndrome; in one patient it evolved into acute myeloid leukemia with monosomy 7 in the marrow. The hematologic complications have hitherto not been previously reported in other cases of 3-methylglutaconic aciduria and are thus thought to represent a new disease entity. This family adds additional evidence to the genetic heterogeneity of Mendelian disorders in which the primary mutation may have a mutator effect that could give origin to myelodysplastic syndrome and acute myeloid leukemia through acquired chromosomal changes.

Organic acidurias and related abnormalities

Organic acid analysis is a powerful technique in the diagnosis of inborn errors of metabolism. Since the development of the technique over twenty-five years ago, it has evolved into a sophisticated and powerful method and is an essential tool in the diagnosis of the organic acidurias. The chemistry and biochemistry of organic acids, as well as sample preparation, instrumentation, and many aspects of the more commonly used methods for the analysis of these compounds, are reviewed. The biochemical and clinical characteristics of each of the primary organic acidurias are described. In addition, the various noninherited causes of secondary organic acidurias that lead to the excretion of abnormal organic acids are also described, and ways of differentiating primary from secondary causes are discussed.