Spinocerebellar ataxia

Spinocerebelarne ataksije (SCA) su heterogena grupa dominantno nasljednih bolesti karakteriziranih cerebelarnom ataksijom i mnoštvom dodatnih cerebelarnih i ekstracerebelarnih simptoma. Ataksija je simptom, a ne specifična bolest ili dijagnoza, a očituje se slabom koordinacijom pokreta. Uz mali mozak u većini SCA najčešće je zahvaćena kralježnička moždina te se zbog toga i nazivaju tim imenom. Osim malog mozga i kralježničke moždine bolešću mogu biti zahvaćeni bazalni gangliji, piramidalni sustav, produžena moždina i periferni živčani sustav. Uzrokovane su različitim genskim mutacijama od kojih je najčešća ekspanzija CAG tripleta u genima za protein nazvan ataksin. Mutacije pokazuju izrazitu sklonost anticipaciji, tj. pogoršavanju simptoma u idućim generacijama. SCA spadaju u skupinu rijetkih bolesti čija je prevalencija 3-4,2/ 100.000. Postoji najmanje 30 različitih tipova SCA, a nazvane su redoslijedom otkrivanja bolesti. SCA 9 i 24 još nisu identificirane. Kod većine njih simptomi se javljaju u odrasloj dobi i uglavnom sporo progrediraju. Najčešći tip je SCA 3, a prevalencija pojedinih SCA ovisi o geografskom području. Kliničke slike pojedinih ataksija izrazito se preklapaju i zbog toga je konačna dijagnoza moguća jedino genetičkim testom. Ne postoji kauzalno i posve učinkovito liječenje, no simptomatska terapija olakšava brojne simptome bolesti.Spinocerebellar ataxias (SCA) are a heterogeneous group of autosomal dominant diseases characterized by cerebellar ataxia in association with many cerebellar and extracerebellar symptoms. Ataxia is a symptom, not a specific disease or diagnosis and it is presented with weak coordination of movement. With cerebellum, the most common affected structure in SCA is the spinal cord and that is why they are called by that name. Beside cerebellum and the spinal cord, the disease can affect basal ganglia, pyramidal system, brainstem and peripheral nervous system. SCA are caused by different gene mutations among which the most common is the CAG trinucleotide repeat in genes for protein called ataxin. These mutations shows great tendency for anticipation, which means increasing the symptoms in subsequent generation. They belong to a group of rare diseases with the prevalence of 3-4,2/ 100.000. There are at least 30 different types of SCA and they are called by the order of identification. Most of the SCA usually have adult-onset. The most common type is SCA 3, and the prevalence of each SCA depends on the geographic area. Clinical findings of different SCA overlap and that is why the diagnosis is possible only with a genetic test. There is no causal and efficient therapy for SCA, but supportive therapy reduces many symptoms of the disease