Clinical and genetic analysis of juvenile-onset Huntington's disease: 10 cases report

Abstract

Objective To investigate the clinical features and dynamic mutation of 10 cases with juvenile-onset Huntington's disease (HD).  Methods The cytosine-adenine-guanine (CAG) repeats of IT15 gene were detected by polymerase chain reaction (PCR) and capillary electrophoresis in 272 individuals of 159 pedigrees with preliminary diagnosis of HD. The correlation between clinical features and expanded CAG repeats in the IT15 gene of 10 cases with juvenile-onset HD were studied carefully.  Results Among 211 individuals carried expanded CAG repeats, 10 cases onset before 20 years of age. The predominant clinical manifestations were involuntary movement and cognitive impairment. The average age of onset was (12.50 ± 4.55) years, and the average CAG repeat number of IT15 gene was 63.70 ± 14.83. Pearson correlation analysis showed that the age of onset was significantly and negatively correlated with the CAG repeat number (r = - 0.865, P = 0.001). Conclusions 1) The juvenile?onset case of HD presented with different clinical features compared with adult - onset cases. The most common presentation is cognitive decline. 2) Analysis of CAG repeats of IT15 gene is necessary for the diagnosis of juvenile-onset case of HD with no family history. 3) The variability in age of onset is not completely explained by the effects of expanded CAG repeats of IT15 gene, which is more prominently for the juvenile?onset cases, therefore, it is
suggested that other factors may modulate the age of onset.

DOI: 10.3969/j.issn.1672-6731.2017.08.008