Heart Transplantation for a Patient With Kearns-Sayre Syndrome and End-Stage Heart Failure

Cardiomyopathies in Children and Systemic Disorders When Is It Useful to Look beyond the Heart?

Cardiomyopathy (CMP) is a rare disease in the pediatric population, with a high risk of morbidity and mortality. The genetic etiology of CMPs in children is extremely heterogenous. These two factors play a major role in the difficulties of establishing standard diagnostic and therapeutic protocols. Isolated CMP in children is a frequent finding, mainly caused by sarcomeric gene variants with a detection rate that can reach up to 50% of analyzed cohorts. Complex multisystemic forms of pediatric CMP are even more heterogenous. Few studies in literature take into consideration this topic as the main core since it represents a rarity (systemic CMP) within a rarity (pediatric population CMP). Identifying etiology in this cohort is essential for understanding prognosis, risk stratification, eligibility to heart transplantation and/or mechanical-assisted procedures, preventing multiorgan complications, and relatives' recurrence risk calculation. The previous points represent a cornerstone in patients' empowerment and personalized medical care approach. The aim of this work is to propose a new approach for an algorithm in the setting of the diagnostic framework of systemic pediatric CMP. On the other hand, during the literature review, we noticed a relatively common etiologic pattern in some forms of complex/multisystem CMP. In other words, certain syndromes such as Danon, Vici, Alström, Barth, and Myhre syndrome share a common pathway of directly or indirectly defective "autophagy" process, which appears to be a possible initiating/triggering factor for CMPs. This conjoint aspect could be important for possible prognostic/therapeutic implications in this category of patients. However, multicentric studies detailed functional and experimental models are needed prior to deriving conclusions.

Moving towards clinical trials for mitochondrial diseases

Primary mitochondrial diseases represent some of the most common and severe inherited metabolic disorders, affecting ~1 in 4,300 live births. The clinical and molecular diversity typified by mitochondrial diseases has contributed to the lack of licensed disease-modifying therapies available. Management for the majority of patients is primarily supportive. The failure of clinical trials in mitochondrial diseases partly relates to the inefficacy of the compounds studied. However, it is also likely to be a consequence of the significant challenges faced by clinicians and researchers when designing trials for these disorders, which have historically been hampered by a lack of natural history data, biomarkers and outcome measures to detect a treatment effect. Encouragingly, over the past decade there have been significant advances in therapy development for mitochondrial diseases, with many small molecules now transitioning from preclinical to early phase human interventional studies. In this review, we present the treatments and management strategies currently available to people with mitochondrial disease. We evaluate the challenges and potential solutions to trial design and highlight the emerging pharmacological and genetic strategies that are moving from the laboratory to clinical trials for this group of disorders.

Perspectives in Pediatric Pathology, Chapter 21. Testicular Pathology in Heritable Metabolic Disease

Inborn errors of metabolism have wide and profound effects in many or all organs, and especially so in those with endocrine functions. The testes are greatly affected by systemic metabolic disorders, leading to specific histological findings that generally reveal the nature of the underlying disorder. Here we describe the main testicular changes seen in the setting of metabolic disease.

Solid organ transplantation in primary mitochondrial disease: Proceed with caution

Solid organ transplants are rarely performed in both adult and pediatric patients with primary mitochondrial disease. Poor outcomes have been described in case reports and small case series. It is unclear whether the underlying genetic disease has a significant impact on post-transplant morbidity and mortality. Data were obtained for 35 patients from 17 Mitochondrial Disease Centers across North America, the United Kingdom and Australia. Patient outcomes were noted after liver, kidney or heart transplantation. Excluding patients with POLG-related disease, post-transplant survival approached or met outcomes seen in non-mitochondrial disease transplant patients. The majority of mitochondrial disease patients did not have worsening of their mitochondrial disease within 90-days post-transplant. Post-transplant complications, including organ rejection, were not a common occurrence and were generally treatable. Many patients did not have a mitochondrial disease considered or diagnosed prior to transplantation. In conclusion, patients with mitochondrial disease in this cohort generally tolerated solid-organ transplantation. Such patients may not need to be excluded from transplant solely for their mitochondrial diagnosis; additional caution may be needed for patients with POLG-related disease. Transplant teams should be aware of mitochondrial disease as an etiology for organ-failure and consider appropriate consultation in patients without a known cause of their symptoms.

Heart Disease in Disorders of Muscle, Neuromuscular Transmission, and the Nerves

Little is known regarding cardiac involvement (CI) by neuromuscular disorders (NMDs). The purpose of this review is to summarise and discuss the major findings concerning the types, frequency, and severity of cardiac disorders in NMDs as well as their diagnosis, treatment, and overall outcome. CI in NMDs is characterized by pathologic involvement of the myocardium or cardiac conduction system. Less commonly, additional critical anatomic structures, such as the valves, coronary arteries, endocardium, pericardium, and even the aortic root may be involved. Involvement of the myocardium manifests most frequently as hypertrophic or dilated cardiomyopathy and less frequently as restrictive cardiomyopathy, non-compaction, arrhythmogenic right-ventricular dysplasia, or Takotsubo-syndrome. Cardiac conduction defects and supraventricular and ventricular arrhythmias are common cardiac manifestations of NMDs. Arrhythmias may evolve into life-threatening ventricular tachycardias, asystole, or even sudden cardiac death. CI is common and carries great prognostic significance on the outcome of dystrophinopathies, laminopathies, desminopathies, nemaline myopathy, myotonias, metabolic myopathies, Danon disease, and Barth-syndrome. The diagnosis and treatment of CI in NMDs follows established guidelines for the management of cardiac disease, but cardiotoxic medications should be avoided. CI in NMDs is relatively common and requires complete work-up following the establishment of a neurological diagnosis. Appropriate cardiac treatment significantly improves the overall long-term outcome of NMDs.