Department of Neurology, Rouen University Hospital, Rouen, France.
Am J Med Genet A. 2011 Apr;155A(4):815-8. doi: 10.1002/ajmg.a.33911. Epub 2011 Mar 15.
Juvenile Huntington disease (JHD) is a rare clinical entity characterized by disease onset before the age of 21. JHD accounts for <10% of Huntington disease patients. Transmission of JHD is paternal in 80-90% of cases. Patients with JHD usually carry more than 60 CAG repeats within the HTT gene. We report here on a 23-month-old boy presenting with global developmental delay first noted at 18 months of age. Clinical examination showed truncal hypotonia, postural and intentional tremor, limb rigidity, and ataxia. Cerebral magnetic resonance imagery (MRI) showed reduced cerebellar volume. Six months later, his 47-year-old father was seen for a 4-year history of progressive dementia with severe behavioral disturbance and chorea. Cerebral MRI showed discrete global and caudate atrophy. DNA analysis revealed a very large and heterogeneous expansion (210-250 CAG) in the child and a 43 CAG expansion of the HTT gene in the father. This unusual case demonstrates that very early onset JHD due to large CAG expansions should be considered in cases of global developmental delay associated with reduced cerebellar volume, including cases without known HD family history.
青少年亨廷顿病（JHD）是一种罕见的临床病症，其特征是在 21 岁之前发病。JHD 占亨廷顿病患者的<10%。80-90%的 JHD 病例是由父系遗传的。JHD 患者通常在 HTT 基因内携带超过 60 个 CAG 重复。我们在此报告了一例 23 个月大的男孩，其主要表现为 18 个月时出现的全面发育迟缓。临床检查显示躯干张力减退、姿势性和意向性震颤、肢体僵硬和共济失调。脑磁共振成像（MRI）显示小脑体积减小。6 个月后，他 47 岁的父亲因进行性痴呆症就诊，病史为 4 年，伴有严重的行为障碍和舞蹈病。脑 MRI 显示广泛且明显的大脑和尾状核萎缩。DNA 分析显示孩子的 HTT 基因有一个非常大且不均匀的扩展（210-250 CAG），而父亲的 HTT 基因有 43 CAG 的扩展。这个不寻常的病例表明，对于伴有小脑体积减小、包括无已知亨廷顿病家族史的全面发育迟缓的病例，应考虑与大 CAG 扩展相关的非常早发性 JHD。
