Mitochondrial cytopathies: clinical, morphological and genetic characteristics.
OBJECTIVE
Mitochondrial cytopathies are heterogeneous disorders affecting multiple systems but most commonly involving the skeletal muscle and central nervous system. The variety of symptoms and signs requires biochemical, morphological and genetic evaluation. The results of genetic studies indicate that there is no direct correlation between genotype and phenotype in mitochondrial cytopathies. This study is the first such analysis of a group of Polish patients with mitochondrial cytopathies. Its aim is to define the clinical features of mitochondrial cytopathies in relation to their genetic defects.


METHODS
In a retrospective study, 46 patients with final diagnosis of mitochondrial cytopathy were evaluated clinically and electrophysiologically. Each patient underwent electromyography, electroneurography, and some patients were also assessed using electroencephalography. Clinical diagnoses were confirmed through the histopathological evaluation of muscle biopsies. In 36 cases mitochondrial DNA (mtDNA) testing was performed.


RESULTS
Eight different clinical syndromes were diagnosed among the evaluated patients. In the skeletal muscle biopsy, ragged-red fibres, which are a significant symptom for these disorders, were present in the majority of cases (93%). The presence of specific gene mutations was confirmed in 9 out of the 36 cases in which mtDNA was examined.


CONCLUSIONS
The results of our study confirm the remarkable clinical heterogeneity of mitochondrial cytopathies. Final diagnosis in many cases could only be confirmed by detection of the genetic defects. Molecular diagnosis may in the future have a significant impact on new therapeutic approaches.
Kierdaszuk
Biruta
B
Klinika Neurologii, Warszawski Uniwersytet Medyczny, 02-097 Warszawa. bi_ruta@vp.pl
Jamrozik
Zygmunt
Z
Tońska
Katarzyna
K
Bartnik
Ewa
E
Kaliszewska
Magdalena
M
Kamińska
Anna
A
Kwieciński
Hubert
H
D000293:Adolescent; D000328:Adult; D000368:Aged; D001706:Biopsy; D002648:Child; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D008931:Mitochondria, Muscle / Q000235:genetics; D017240:Mitochondrial Myopathies / Q000145:classification* / Q000235:genetics* / Q000473:pathology; D018482:Muscle, Skeletal / Q000473:pathology*; D011044:Poland; D012189:Retrospective Studies
D004272:DNA, Mitochondrial