Dürr A, Brice A, Lepage-Lezin A, Cancel G, Smadja D, Vernant J C, Agid Y
INSERM U289, Hôpital de la Salpêtrière, Paris, France.
Clin Neurosci. 1995;3(1):12-6.
Spinocerebellar ataxia 2 (SCA2) is one of the loci for the clinically and genetically heterogeneous group of autosomal dominant type I cerebellar ataxias. After initial linkage to chromosome 12q in Cuban families, SCA2 was shown to be the gene responsible for the disease in Italian, Tunisian, French-Canadian, Austrian-Canadian and Martinican kindreds with dominant ataxia, and the candidate interval was reduced to 6.4 cM between markers D12S84 and D12S79. Comparison of patients from families of different geographical origins clearly demonstrates the clinical interfamilial variability of the clinical signs which reaches statistical significance for the frequency of extrapyramidal rigidity, postural tremor and dementia. The most striking difference between the 29 Martinican SCA2 patients and those with SCA1 on chromosome 6p or SCA3/MJD on chromosome 14q is the greater frequency of hyporeflexia in the former. A mean 12.5 year anticipation is observed, with a more rapid clinical course of the disease in successive generations, indicating that an expanded trinucleotide repeat probably constitutes the underlying molecular mechanism.
脊髓小脑共济失调2型（SCA2）是常染色体显性I型小脑共济失调临床和遗传异质性群体的基因位点之一。在古巴家族中首次发现与12号染色体长臂连锁后，SCA2被证明是意大利、突尼斯、法裔加拿大、奥地利裔加拿大和马提尼克岛具有显性共济失调的家族中导致该疾病的基因，候选区间缩小到标记D12S84和D12S79之间的6.4厘摩。对来自不同地理区域家族的患者进行比较，清楚地显示出临床体征在家族间的变异性，这在锥体外系僵硬、姿势性震颤和痴呆的频率方面具有统计学意义。29名马提尼克岛SCA2患者与6号染色体短臂上的SCA1患者或14号染色体长臂上的SCA3/MJD患者之间最显著的差异是前者反射减退的频率更高。观察到平均12.5年的遗传早现现象，疾病在连续几代中的临床进程更快，这表明三核苷酸重复序列的扩增可能构成潜在的分子机制。
