A 15-year-old boy is brought to the office by his mother due to difficulty with movement. The patient enjoys playing high school basketball but had to leave the team this year due to his progressively worsening symptoms. On examination, he is found to have significant kyphoscoliosis and a high plantar arch. His older brother suffered from a neurologic disorder and died of heart failure at age 25. This patient most likely has which of the following neuropathologic findings?

Question

A 15-year-old boy is brought to the office by his mother due to difficulty with movement.  The patient enjoys playing high school basketball but had to leave the team this year due to his progressively worsening symptoms.  On examination, he is found to have significant kyphoscoliosis and a high plantar arch.  His older brother suffered from a neurologic disorder and died of heart failure at age 25.  This patient most likely has which of the following neuropathologic findings?

Quizplus · Accepted Answer

11ec160b_39be_32c8_9249_8393b38242ca_MD0001_00 Friedreich ataxia is an autosomal recessive disorder caused by mutation of the frataxin (FXN) gene. This gene codes for an essential mitochondrial protein involved in the assembly of iron-sulfur enzymes. An increased number of trinucleotide repeats (GAA) is present in the mutated gene, causing decreased FXN expression. This leads to decreased mitochondrial energy production and increased oxidative stress, resulting in degeneration of neural tracts and peripheral nerves. The following sites of involvement are characteristic: (Choice A) Huntington disease is an autosomal dominant disorder caused by trinucleotide repeats (CAG) in the huntingtin (HTT) gene, which results in severe neuronal loss in the caudate nucleus. This condition manifests with dementia, behavioral abnormalities, and choreiform movements. (Choice B) Cerebral cortex atrophy occurs in Alzheimer and Pick diseases. Alzheimer disease is characterized by diffuse, mild cortical atrophy and progressive memory loss. Pick disease causes pronounced frontotemporal atrophy, illustrated by behavioral and emotional abnormalities. (Choice D) Charcot-Marie-Tooth disease is an autosomal dominant disorder associated with demyelination of peripheral nerves. Typical findings include distal leg weakness/atrophy with sensory deficits, pes cavus, and kyphoscoliosis; cardiomyopathy is not characteristic. (Choice E) Loss of neurons in the anterior horn of the spinal cord occurs in poliomyelitis and leads to flaccid paralysis, atrophy, areflexia, and muscle fasciculations. Damage of these neurons also occurs in amyotrophic lateral sclerosis. (Choice F) Loss of neurons of the substantia nigra occurs in Parkinson disease, which manifests with bradykinesia, rigidity, and a resting "pill-rolling" tremor. Educational objective: Friedreich ataxia is characterized by cerebellar ataxia (spinocerebellar tract degeneration) and loss of position/vibration sensation (dorsal column/dorsal root ganglia degeneration), kyphoscoliosis, and hypertrophic cardiomyopathy. Foot abnormalities and diabetes mellitus are also common. __________ References: Clinical features of Friedreich's ataxia: classical and atypical phenotypes. (http://www.ncbi.nlm.nih.gov/pubmed/23859346)

A 15-Year-Old Boy Is Brought to the Office by His