Elia M, Guerrini R, Musumeci S A, Bonanni P, Gambardella A, Aguglia U
Department of Neurology, Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Troina, Italy.
Epilepsia. 1998 Jun;39(6):660-3. doi: 10.1111/j.1528-1157.1998.tb01435.x.
We explored the relationship between myoclonic absence seizures (MAS) and underlying chromosome disorders.
Among 14 patients with MAS observed in three centers, 5 had typical cryptogenic myoclonic absence epilepsy (MAE), 2 had MAS associated with other seizure types (1 with signs of a neuronal migration abnormality and 1 with signs of a metabolic disorder), and 7 had MAS, with or without other seizure types, complicating a chromosome abnormality syndrome-2 with trisomy 12p, 4 with Angelman syndrome, and 1 with inv dup (15).
In the 7 patients with chromosomopathy, MAS appeared at a mean age of 2.9 years (range 4 months to 6 years 6 months), had a duration of 4-20 s, and were accompanied by reduced awareness and rhythmic myoclonic jerks involving proximal limb muscles. Ictal EEG showed 2- to 3-Hz generalized spike-and-wave discharges.
In these patients, MAS differed slightly from those of typical MAE: age of onset was earlier, absences were of shorter duration, and no clear increase in muscular tone was noted. Abnormal expression of genes codifying for the subfamily of K+ channels and for gamma-aminobutyric acid-3 subunit receptors (GABRB3), both located in the chromosome segments involved in the chromosomopathies presented by our patients, could be responsible for the same generalized seizure type. Chromosome analysis should be performed in patients with mental retardation and MAS, especially when the ictal pattern does not completely overlap that observed in MAE.
我们探讨了肌阵挛失神发作（MAS）与潜在染色体疾病之间的关系。
在三个中心观察的14例MAS患者中，5例患有典型的隐源性肌阵挛失神癫痫（MAE），2例MAS伴有其他发作类型（1例有神经元迁移异常体征，1例有代谢紊乱体征），7例MAS伴有或不伴有其他发作类型，并发染色体异常综合征——2例12号染色体短臂三体，4例天使综合征，1例inv dup(15)。
在7例染色体病患者中，MAS平均发病年龄为2.9岁（范围4个月至6岁6个月），持续时间为4 - 20秒，伴有意识减退和累及近端肢体肌肉的节律性肌阵挛抽搐。发作期脑电图显示2 - 3Hz的广泛性棘慢波放电。
在这些患者中，MAS与典型MAE略有不同：发病年龄更早，失神持续时间更短，且未观察到肌张力明显增加。位于我们患者所患染色体病相关染色体片段上的钾离子通道亚家族和γ-氨基丁酸-3亚基受体（GABRB3）编码基因的异常表达，可能是导致相同全身性发作类型的原因。对于智力发育迟缓且伴有MAS的患者，尤其是发作期模式与MAE不完全重叠时，应进行染色体分析。
