Rapidly progressive frontotemporal dementia and bulbar amyotrophic lateral sclerosis in Portuguese patients with C9orf72 mutation

Abstract

Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) form a spectrum of clinically, pathologically, and genetically overlapping disorders, as confirmed by the recent report that it can be caused by a hexanucleotide repeat expansion in C9orf72. One hundred and fourteen Portuguese cases diagnosed as probable or possible familial FTLD, as part of the EOD consortium study, and nine further Portuguese cases with familial ALS were tested for the presence of this mutation. Results showed that six Portuguese patients from unrelated families had the mutation, five (4.4%) patients from the FTLD group and one (11.1%) from the ALS sample. Of these, three patients had FTLD and rapidly progressive bulbar ALS. Electromyography confirmed diffuse loss of motor units with marked bulbar involvement. In conclusion, the cases now reported showed a very rapid progression, suggesting bulbar ALS could be particularly common and aggressive in patients with the C9orf72 hexanucleotide repeat expansion, in the Portuguese population.

Key words::

• Amyotrophic lateral sclerosis
• frontotemporal lobar degeneration
• frontotemporal dementia
• hexanucleotide repeat expansion
• C9orf72

Acknowledgements

The authors are grateful to Manuela Guerreiro for neuropsychological evaluation of the patients, as well as to Guy Rouleau and Daoud Hussein from the Centre de Recherche CHUM, Notre-Dame Hospital, Montreal, for testing ALS cases. The genetic analysis of the C9orf72 gene in the Portuguese patients with FTLD was in part funded by the Interuniversity Attraction Poles program of the Belgian Science Policy Office; the Methusalem program of the Flemish Government; the Research Foundation − Flanders (FWO). The FWO provided a postdoctoral fellowship to J.v.d.Z. This work was partially supported by “Funda o para a Ci ncia e Tecnologia” – PIC/IC/82765/2007.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.