神经系统疾病

Friedreich Ataxia: Clinical Report of an Uncommon Point Mutation (R165C)

Abstract

Rosa María García Tercero, Javier Gualda Heras, Catalina Diaz Urrea, Pedro Barredo Benitez, Adolfo Heras Pérez, Fátima López González, Blanca serrano Serrano, Elena Elvira Soler and Carmina Díaz Marín

Introduction: Friedreich ataxia (FRDA) is the most common hereditary ataxia now. It is inherited as an autosomal recessive disease. Most of the patients are homozygotes, with an expansion of a GAA triplet in both alleles of the first intron of the frataxin gene (FXN, 9q13) (95-98% of the patients). The rest of the patients are heterozygotes with an expansion in only one allele and a point mutation in the other. These cases are more difficult to diagnose due to the low prevalence and the needed of enlarge molecular tests. Case Report: An ambulant 42-year-old man was referred to our hospital due to gait instability that had started 7 years ago. A clinical examination showed gait ataxia, areflexia, decrease vibration sense, scoliosis, and pes cavus. Results and Discussion: Laboratory tests, neuroimaging and neurophysiologic studies had been done since then without relevant findings. Somatosensory evoked potentials were also done and described a sensitive axonal neuropathy with an affectation of the posterior columns of the spinal cord. Due findings of 300-350 repetitions of GAA in one allele and the point mutation R165C in the other that confirmed the diagnosis. Conclusion: This case report highlights that, although most patients of Friedreich ataxia are usually homozygotes, there are a small number of patients that are heterozygotes and can have different phenotypes being important to identify them to give genetic counselling and detect new complications that suppose a risk for their lives.