Complex multisystem phenotype associated with the mitochondrial DNA m.5522G>A mutation

Camptocormia and Other Orthopedic Compromise Dominating Mitochondrial Disorder: A Case Report

Objectives: Camptocormia and other orthopedic abnormalities have been only rarely reported as a phenotypic manifestation of a mitochondrial disorder (MID). Here we present an MID patient with multiple orthopedic abnormalities dominating the phenotype.

Case report: The patient is a 55-year-old male in whom MID was diagnosed at age 34 upon clinical presentation, muscle biopsy, and biochemical investigations. Phenotypically, he manifested with multisystem disease including the brain (mental retardation, epilepsy, sleep disorder, cerebellar atrophy), eyes (cataract, myopia), ears (hypoacusis), heart (hypertrophic, cardiomyopathy, QT-prolongation, left anterior hemiblock, noncompaction), intestines (hepatopathy, cholecystolithiasis), muscle (myopathy), peripheral nerves (neuropathy), and the bone marrow (anemia). Additionally, there was facial dysmorphism (upslanting palpebral fissures, hypertelorism, protruding bulbs) and multiple orthopedic abnormalities, including camptocormia in the absence of axial myopathy, barrel thorax, gibbus, genu valga, knee contractures, bilateral gonarthrosis, bilateral ankle arthroses, and outwardly rotated feet. These abnormalities were complicated by wedge vortex, vertebral stenosis, and coxarthrosis requiring right hip endoprosthesis. His mother manifested with a largely different phenotype.

Conclusions: An MID can manifest phenotypically with orthopedic abnormalities, which may dominate the phenotype. According to this case, orthopedic abnormalities in a MID can be unrelated to the severity of myopathy and intrafamilial phenotypic variability can be high in a MID.

Genetic aspects of the oxidative phosphorylation dysfunction in dilated cardiomyopathy

Dilated cardiomyopathy is a frequent and extremely heterogeneous medical condition. Deficits in the oxidative phosphorylation system have been described in patients suffering from dilated cardiomyopathy. Hence, mutations in proteins related to this biochemical pathway could be etiological factors for some of these patients. Here, we review the clinical phenotypes of patients harboring pathological mutations in genes related to the oxidative phosphorylation system, either encoded in the mitochondrial or in the nuclear genome, presenting with dilated cardiomyopathy. In addition to the clinical heterogeneity of these patients, the large genetic heterogeneity has contributed to an improper allocation of pathogenicity for many candidate mutations. We suggest criteria to avoid incorrect assignment of pathogenicity to newly found mutations and discuss possible therapies targeting the oxidative phosphorylation function.

Letter to the Editor: Comments on "Obesity associated with a novel mitochondrial tRNACys m.5802A>G mutation in a Chinese family"

In a recent article Wang et al. reported about a 9-year-old Chinese male with obesity, insulin resistance, acanthosis nigricans, hyperuricemia, and non-alcoholic fatty liver disease (NALFD) being attributed to the variant m.5802A>G in tRNA(Cys) (Bioscience Reports (2020) 40(1), BSR20192153). Pathogenicity of the variant was substantiated by documentation of perturbed stability and mobility of the tRNA(Cys). The interesting study has a number of shortcomings, which do not allow drawing conclusions as provided before they are solved. Obesity is multifactorial and many differential causes of mtDNA variants were not discussed or excluded.

Unusual Phenotype and Disease Trajectory in Kearns-Sayre Syndrome

OBJECTIVE

To describe unusual course and unusual phenotypic features in an adult patient with Kearns-Sayre syndrome (KSS). Case Report. The patient is a 49-year-old male with KSS, diagnosed clinically upon the core features, namely, onset before the age 20 of years, pigmentary retinopathy, and ophthalmoparesis, and the complementary features, namely, elevated CSF protein, cardiac conduction defects, and cerebellar ataxia. The patient presented also with other previously described features, such as diabetes, short stature, white matter lesions, hypoacusis, migraine, hepatopathy, steatosis hepatis, hypocorticism (hyponatremia), and cataract. Unusual features the patient presented with were congenital anisocoria, severe caries, liver cysts, pituitary enlargement, desquamation of hands and feet, bone chondroma, aortic ectasia, dermoidal cyst, and sinusoidal polyposis. The course was untypical since most of the core phenotypic features developed not earlier than in adulthood.

CONCLUSIONS

KSS is a multisystem disease, but the number of tissues affected is higher than so far anticipated. KSS should be considered even if core features develop not earlier than in adulthood and if unusual features accompany the presentation.

Cluster headache as a manifestation of a stroke-like episode in a carrier of the MT-ND3 variant m.10158T>C

In a recent article Fu et al reported about a 52 years old female with a mitochondrial disorder due to the variant m.10158T>C in the mtDNA located gene MT-ND3. The study has a number of shortcomings. The study would particularly profit from providing more data about multisystem disease, from providing the current medication, the cerebro-spinal fluid findings, the detailed phenotypic presentation, and the genotype of first-degree relatives. Since the index patient had experienced recurrent seizures it is crucial to know the current and previous anti-seizure medication as it may strongly determine the outcome. Some of them are mitochondrion-toxic and particularly valproic acid may exhibit fatal side effects. The outcome may also depend on the degree of multisystem involvement why it is crucial to prospectively investigate the patient for subclinical involvement of organs not obviously affected. Additionally, the outcome of the stroke-like lesions on imaging would be interesting to see. Stroke-like lesions may completely disappear or may end up as white matter lesion, laminar cortical necrosis, focal atrophy, cyst, or as the so-called toenail sign. There is also a need of discussing more profoundly the imaging findings and their diagnostic significance and to investigate first degree relatives of the index patient clinically and genetically. Though highly interesting, the presentation of this case of a mitochondrial disorder lacks clinical and genetic data of the patient and his relatives. Outcome parameters, such as severity of disease, degree of progression, drugs, pathogenicity of the mutation, and multisystem involvement require a profound discussion.