[Abnormal expansion of C9orf72 gene in familial frontotemporal dementia]. / Expansión anormal de hexanucleótido en gen C9orf72 en una familia con demencia frontotemporal y cuadros asociados.

Frontotemporal Dementia (FTD) and Motor Neuron Disease (MND) may share similar pathogenic mechanisms. An abnormal hexanucleotide expansion in C9orf72 gene is the most common genetic abnormality of these conditions and explains their concurrence in the same family. We report a 77-year-old female presenting with non-fluent aphasia leading to mutism and a mild Parkinsonism. A magnetic resonance imaging showed a severe atrophy of frontal and temporal lobes. Several family members of the patient suffered of atypical Parkinsonism, lateral amyotrophic sclerosis and dementia. We identified an abnormal hexanucleotide expansion in the C9orf72 gene in the proband. To the extent of our knowledge, this is the first time that this diagnosis is confirmed in our country. The knowledge of the genetic basis of neuro degenerative disorders improves diagnosis and opens expectatives for future treatments of these disabling conditions.