Results
A 17-year-old boy from a consanguineous Tuareg family (Figure 1A) was seen for walking difficulty. His past medical history was consistent with normal pregnancy and delivery, and no developmental delay. He is the second child of a sibship of seven, and presented symptoms at age 11 starting with hand tremor and slurred speech. Then, parents noticed progressive walking difficulty followed by frequent falls few months later, and skeletal deformities were noticed around age 14. These symptoms worsened gradually leading the patient to being wheel-chair bound at age 16.
Clinical examination found dysarthria with very few words, spasticity with brisk and diffuse reflexes, hypertonia with scissor legs, loss of vibration and joint sense, and bilateral extensor plantar responses. In addition, he had scoliosis, lumbar kyphosis and pes cavus (Figure 1B & C). Cardiologic, ophthalmologic and ENT examination revealed no abnormalities. Brain MRI showed cerebellar atrophy (Figure 1D) while nerve conduction study revealed axonal sensory polyneuropathy. Blood chemistries including blood glucose and cell counts were normal, but platelet and vitamin B12 levels were high. These features are consistent with Friedreich ataxia, and the testing of the FXN gene associated with this disease identified GAA expansions in the first intron of the gene in both alleles. The first allele had 999 GAA expansion while the second had 766. This haplotype was not previously reported. Clinical and laboratory findings are summarized in Table 1.