title: [Molecular genetic approach to spinocerebellar ataxias].
abstract: Spinocerebellar ataxia (SCA) is a group of degenerative ataxias with autosomal dominant inheritance. The most common form of mutation that causes SCA is the expansion of trinucleotide (CAG) repeat encoding polyglutamine. These "polyglutamine disorders" are, SCA1, SCA2, Machado-Joseph disease, SCA6, SCA7, SCA17 and DRPLA. Another dynamic mutation, yet a non-coding one, has been identified as the cause of SCA8, SCA10 and SCA12. This mutation includes, trinucleotide (CAG/CTG) expansion causing SCA8 and SCA12, and pentanuclotide (ATTCT) expansion leading SCA10. In addition to these dynamic mutations, static mutations, such as missense mutations and deletions, have been identified to cause SCA5, SCA11, SCA13, SCA14, SCA15 and SCA27. Since 1992, authors have been involved in identifying the mutation (s) of autosomal dominant cerebellar ataxia with rather pure cerebellar syndrome (ADCAIII). About a half of our cohort with ADCAIII were SCA6, caused by a small CAG repeat expansion in the alpha1A-voltage-dependent calcium channel gene. Recent study in patients' brains suggested that a small polyglutamine expansion leads a portion of this channel protein to aggregate in the Purkinje cell. Another type of ADCAIII is the chromosome 16q22.1-linked ADCA. By a comprehensive positional cloning strategy, we have found a genetic change that segregate with the disease. Identifying the mutation of 16q-ADCA is imperative for understanding molecular basis of this disease.
authors.affiliation: Department of Neurology and Neurological Sciences, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Kinya
authors.initials: K
authors.lastname: Ishikawa
authors.forename: Taro
authors.initials: T
authors.lastname: Ishiguro
authors.forename: Makoto
authors.initials: M
authors.lastname: Takahashi
authors.forename: Nozomu
authors.initials: N
authors.lastname: Sato
authors.forename: Takeshi
authors.initials: T
authors.lastname: Amino
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Niimi
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Mizusawa
mesh_terms: D015220:Calcium Channels / Q000235:genetics; D002885:Chromosomes, Human, Pair 16 / Q000235:genetics; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics; D006801:Humans; D009154:Mutation; D010455:Peptides / Q000235:genetics*; D013049:Spectrin / Q000235:genetics; D020754:Spinocerebellar Ataxias / Q000235:genetics*; D019680:Trinucleotide Repeat Expansion / Q000235:genetics; D020864:Calcium Channels, N-Type
chemical_list: D015220:Calcium Channels; D020662:Guanine Nucleotide Exchange Factors; D010455:Peptides; D013049:Spectrin; C105656:CACNA1A protein, human; D020864:Calcium Channels, N-Type; C503982:PLEKHG4 protein, human; C097188:polyglutamine