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.