Mitochondrial diseases with the main manifestations of cardiomyopathy and respiratory muscle damage / 中华实用儿科临床杂志

Objective The 3243A ＞ G mutation in mitochondrial DNA is a common cause of the classical mitochondrial diseases characterized by neuro-muscular disorders.This study reports a rare case with the main manifestations of mitochondrial disease in children of mitochondrial cardiomyopathy and respiratory muscle damage.Methods The clinical characteristics,diagnosis and treatment,biochemical,pathological and genetic features of a 10-year-old girl were studied.Results The girl was admitted because of heart failure and respiratory failure at the age of 10.Ragged red fibers in skeletal muscles had been noticed.On her mitochondrial gene,3243A ＞ G mutation,Leu tRNA (UUR),was detected.The mutation rate in the peripheral blood cells was 94％.After the treatment with a high dose of creatine phosphate sodium,coenzyme Q10 and L-carnitine with assisted ventilation,the patient improved rapidly.The child was followed up for 2 years without recurrence.Meanwhile the growth,development and daily life were normal.Conclusions Cardiac and respiratory muscle impairments that appeared at the same time as the first manifestations of the children's mitochondrial disease is not common,and it is rare to have cardiomyopathy based mitochondrial gene 3243A ＞ G mutation is seldom seen clinically.Skeletal muscle biopsy and genetic test is the key for accurate diagnosis.Improving mitochondrial metabolism and assisted ventilation appear to be helpful treatments.

Kearns-Sayre Syndrome: 3 Case Reports and Review of Clinical Feature

Kearns-Sayre syndrome, first described by Kearns and Sayre in 1958, is a rare disorder consisting of ptosis, limited movement of both eyes and atypical retinal pigmentary change (salt-pepper like appearance). Most cases have shown an increase in the concentration of mitochondria and ragged-red fiber under Gomori-trichrome staining on muscle biopsy. Occasionally, it is combined with other neurologic and endocrinologic symptoms such as ataxia, dementia, diabetes, and hyperaldosteronism. We recently experienced three cases of male teenaged patients who expressed the clinical features of Kearns-Sayre syndrome.

Pathologic Findings of Mitochondrial Myopathy

Mitochondrial myopathy (MM) has been applied to muscle disease in which mitochondria have abnormal structure, function or both. To characterize the pathologic findings of MM, we examined the ultrastructural and histochemical findings of 24 cases of MM. The ultrastructures of the MM were characterized by abnormal mitochondria in number (pleoconia) and size (megaconia), and showed predominant accumulation of mitochondria in the subsarcolemmal space of myofibers in all cases. Mitochondria contained abnormally shaped cristae (concentric form and gyriform) in 79% of cases. Paracrystalline inclusion which was known to be a characteristics of MM were seen only in 7 cases (29%). Electron dense deposits were more frequently found (77%) in abnormal mitochondria of chronic progressive external opthalmoplegia and Kearn-Sayre syndrome. But, other findings were not specific for the specific clinical entities. On succinate dehydrogenase (SDH) stain, ragged red fibers (RRF) showed more intense positivity than modified Gomori-trichrome stain and definite strong reactive products were present along the periphery of myofibers which showed normal findings on modified Gomori-trichrome stain. In conclusion, ultrastructural findings such as mitochondria showing pleoconia with megaconia, and bizarre shaped cristae may be helpful for the diagnosis of MM and SDH stain is more useful for identification of RRF than modified Gomori-trichrome stains.

A Case of Kearns-Sayre Syudrome

Kearns-Sayer syndrome, a rare mitochondrial disorder, is composed of chronic progressive external ophthalmoplegia, atypical retinal pigmentation and complete heart block, and also causes numerous neurologic or endocrinologic symptoms. On muscle biopsy, a "ragged red fiber" was seen with Gomori trichrome stain, On electron microscopy, aggregations of abnormal mitochondria were demonstrated, confirming the diagnosis of mitochondrial myopathy. We report a case of Kearns-Sayer syndrome we have experienced.

A Case of Chronic Progressive External Ophthalmoplegia

Chronic progressive external ophthalmoplegia(CPEO) is rare syndrome, which is characterized by slowly progressive blepharoptosis, paralysis of extraocular muscle and has involvement of other organs, particularly the retina, heart, endocrine gland, and bony skeleton. Histological examination of muscle showes characteristic ragged red fibers. Electron microscopy reveals a number of abnormal mitochondria which contain paracrystalline inclusion bodies. We experienced a 50-year-old female with CPEO, that was pathologically proven by electron microscopy and bilateral levator levator advancements were given for ptosis.

Clinical Manifestations of Mitochondrial Diseases

According to the recently published reports about mitochondrial diseasbl the clinical manifestations are more various than expected. There have been no clinical studies covering whole spectrum of mitochond7iral disease except a few case reports in our country. The authors performed this studies to understand the various clinical and laboratory findings of mitochondrial disease and the usefulness of current tools for the diagnosis of mitochondrial diseases. We reviewed retrospectively the clinical, laboratory and pathologic findings of mitochondrial disease. The diagnosis of mitochondrial disease was based on clinical manifestations, 'ragged-red fiber' in Gomori stainging, and/or abnormal mitochondrial morphologies on electron microscopy. Twenty one patients were diagnosed as mitochondrial disease. Their clinical diagnosis included 7 MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes); 3 MERRF (myoclonic epilepsy with ragged red fibers); 2 KSS (Kearns-Sayre syndrome); 7 CPEO (chronic progressive external ophthalmoplegia); and 2 mitochondrial myopathy. The usefulness of electrodiagnostic studies, such as EMG, NCV and FEG, were limited in some patients. The muscle biopsy showed ragged red fibers in 10 of 15 sampled examined. Eleven patients had abnormal serum lactic acid level. The authors found that the mitochondrial disease revealed broad clinical spectrum and clinically available diagnostic tests, such as serum lactate and light microscopic examination showed limited value. Therefore, to evaluate the mitochondrial dysfunction with systemic involvement may be desirable to depend on sensitive and specific methods including succinate dehydrogenase (SDH) staining, electron microscopy and biologic studies of mitochondrial DNA.

A case of MELAS syndrome

MELAS syndrome is a rare but distinct clinical entity belonging to a group of mitochondrial encephalomyopathies characterized by the tetrad of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes. We experienced a case of MELAS syndrome in an 8 year-old boy who showed headache, pain of the eyeball, vomiting, stroke-like episodes such as visual disturbance and dysarthria, myoclonic seizure, confusion, and walking disturbance. His serum lactate level was elevated up to 48 mg/dl. MRI findings showed high signal intensities T2-weighted image and low signal intensities in T1-weighted image in the right thalamus and parietooccipital lobe and bilateral symmetric high signal intensity in T1-dweighted image in the basal ganglia. We have seen the dispersed ragged-red fibers with modified Gomori trichrome staining on light microscope, and abundant and dysmorphic mitochondria on electon microscope in the specimen of muscle biopsy. esis of SLE.