Friedreich Ataxia

(M1.NE.15.30) An 8-year-old boy is referred to your neurology clinic with the chief complaint of "trouble walking." His mother believes her son's condition has gradually worsened over the past several months with the recent development of difficulty coordinating his arms. Physical examination is notable for an ataxic gait, nystagmus, and mild dysarthria. You also observe the findings in Figure A on musculoskeletal examination. His mother believes that her husband's brother suffered from similar complaints and passed away at the age of 37 years. Which physical exam findings would you statistically most likely find in this patient's 3-year-old brother?

(M1.NE.15.72) An 8-year-old boy is brought to the pediatrician because his mother is concerned about recent behavioral changes. His mother states that she has started to notice that he is slurring his speech and seems to be falling more than normal. On exam, the pediatrician observes the boy has pes cavus, hammer toes, and kyposcoliosis. Based on these findings, the pediatrician is concerned the child has a trinucleotide repeat disease. Which of the following trinucleotide repeats is this child most likely to possess?

(M1.NE.14.101) A 4-year-old male presents with a 1-year history of swaying while walking and recent episodes of tripping when ambulating. He has trouble trying to sit and get up from chairs, as well as walking up the stairs to his bedroom. On physical exam, the pediatrician notices nystagmus, absent deep tendon reflexes, significant loss of vibratory and proprioceptive sensation in his extremities, pes cavus, and slight kyphoscoliosis. A blood sample is sent for DNA sequencing and the results show a significant expansion of the trinucleotide GAA on chromosome 9. Which of the following diseases displays a similar mode of inheritance as the disease affecting this patient?