Spinocerebellar ataxia type 7 (SCA7) – correlations between phenotype and genotype in one large Belgian family
| Autor: | Jurgen Del-Favero, Jean-Jacques Martin, Ann Löfgren, Nicole Van Regemorter, Christine Van Broeckhoven |
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| Rok vydání: | 1999 |
| Předmět: |
Adult
Male Ataxin 7 Genotype Positional cloning Nerve Tissue Proteins Neuropathology Biology Retina Belgium Trinucleotide Repeats Autosomal dominant cerebellar ataxia Cerebellum medicine Humans Spinocerebellar Ataxias Age of Onset Aged Aged 80 and over Ataxin-7 Genetics Chromosome Mapping Middle Aged medicine.disease Pedigree Phenotype Neurology Child Preschool Anticipation (genetics) Spinocerebellar ataxia biology.protein Female Chromosomes Human Pair 3 Neurology (clinical) Age of onset Trinucleotide repeat expansion |
| Zdroj: | Journal of the neurological sciences |
| ISSN: | 0022-510X |
| DOI: | 10.1016/s0022-510x(99)00176-8 |
| Popis: | Spinocerebellar ataxia type 7 (SCA7), in which the degenerative process also affect the retina, belongs to the category of the autosomal dominant cerebellar ataxia type II (ADCA II). We have described the neuropathology of this condition [Martin JJ, Van Regemorter N, Krols L, Brucher JM, de Barsy T, Szliwowski H, et al. On an autosomal dominant form of retino-cerebellar degeneration: an autopsy study of five patients in one family. Acta Neuropathol (Berl) 1994;88:277-286] in a very large Belgian family (CA-1). We have observed anticipation in the age of onset with increasing severity of the symptoms in consecutive generations. The SCA7 gene was mapped to chromosome 3p12-13 [David G, Abbas N, Stevanin G, Dürr A, Yvert G, Cancel G, et al. Cloning of the SCA7 gene reveals a highly unstable CAG repeat expansion. Nat Genet 1997;17:65-70; Del-Favero J, Krols L, Michalik A, Theuns J, Löfgren A, Goossens D, et al. Molecular genetic analysis of autosomal dominant cerebellar ataxia with retinal degeneration (ADCA type II) caused by CAG triplet repeat expansion. Hum Mol Genet 1998;7:177-186], and the gene identified. SCA7 is a new gene of unknown function that contains an expansion of CAG repeats in SCA7 patients. During the procedure of positional cloning, we examined 26 patients belonging to the CA-1 family and realized, in some of them, an ophthalmologic examination and neuro-imaging of the brain. This allowed us to differentiate four groups: (1) asymptomatic young carriers with 38 to 43 CAG repeats; (2) mildly symptomatic, older patients with 38-41 CAG repeats; (3) patients with the full-blown picture of SCA7 and age of onset during adolescence, with 54-55 CAG repeats; (4) children with early onset and rapid fatal course of the disease who had over 55 CAG repeats. We were able to draw correlations between clinical phenotype, age at onset and CAG repeat number and to make predictions, to some extent, as to the clinical course of the disease in new patients. |
| Databáze: | OpenAIRE |
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