MELAS syndrome in a patient with a point mutation in MTTS1.
BACKGROUND, OBJECTIVE AND METHODS: We describe a female patient with a mitochondrial encephalopathy, lactic acidosis and stroke-like episodes syndrome. As a child, she developed epilepsy and stroke-like episodes giving cognitive impairment and ataxia but no hearing impairment. At the age of 44 years, she suffered a cerebral sinus thrombosis which was warfarin treated. One month later, she developed an episode of severe acidosis associated with encephalopathy and myelopathy.


RESULTS
She was found to harbour a 7512T>C mutation in the mitochondrial encoded tRNA(Ser(UCN)) gene (MTTS1). The mutation load was 91% in muscle and 24% in blood. Enzyme histochemical analysis of the muscle tissue showed numerous cytochrome c oxidase (COX)-negative fibres. Restriction fragment length polymorphism (RFLP) analysis of single muscle fibres showed significantly higher level (median 97%, range: 94-99%) of the mutation in the COX-negative fibres compared with COX-positive fibres (median 36%, range: 12-91%), demonstrating the pathogenic effect of the mutation. Different levels of heteroplasmy (range 34-61%) were detected in hair shafts analysed by RFLP.


CONCLUSIONS
This case adds to the spectrum of clinical presentations, i.e. sinus thrombosis, in patients having MTTS1 mutations.
Lindberg
C
C
Department of Neurology, Neuromuscular Center, Sahlgrenska University Hospital, Göteborg, Sweden. christopher.lindberg@vgregion.se
Moslemi
A-R
AR
Oldfors
A
A
D000328:Adult; D004252:DNA Mutational Analysis / Q000379:methods; D005260:Female; D006801:Humans; D017241:MELAS Syndrome / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D017354:Point Mutation / Q000235:genetics*; D012362:RNA, Transfer, Ser / Q000235:genetics*
D012362:RNA, Transfer, Ser