Clinical spectrum of C9orf72 expansion in a cohort of Huntington’s disease phenocopies
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The expansion in the C9orf72 gene has been recently reported as a genetic cause of Huntington’s disease (HD) phenocopies. We aim to assess the frequency of the C9orf72 gene expansion in a Portuguese HD phenocopies cohort. Twenty HD phenotype-like patients without diagnosis were identified in our institutional database. C9orf72 gene expansion was detected using repeat-primed PCR. Clinical files were reviewed to characterize the phenotype of expansion-positive cases. One patient (5%) was positive for the C9orf72 expansion. A second patient presented 27 repeats—within the intermediate size interval. Both had familial neuropsychiatric disease characterized by diverse movement disorders, dementia, and psychiatric dysfunction that was distinct in severity and clinical expression. C9orf72 disease is clinically heterogeneous and without evident imaging markers. The definition of the role of intermediate alleles and of the pathological threshold for C9orf72 repeat expansions may have diagnostic implications.
KeywordsMovement disorders C9orf72 expansion Huntington’s disease phenocopies Intermediate allele
The authors would like to acknowledge the patients and their family for the participation in this study.
Compliance with ethical standards
Informed consent was obtained from all individual participants included in the study. Additional informed consent was obtained from all individual participants for whom identifying information is included in this article.
Conflict of interest
The authors declare that they have no conflict of interest.
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