Case Workbook for Human Genetics 9th Edition by Ricki Lewis

Exercise 5

A 28-year-old woman sought medical attention over a 6 year period, reporting vomiting and headache, then periodic loss of consciousness and leg cramps, and then loss of hearing, sight, and coordination. Examination of her muscles revealed abnormalities, and she was diagnosed with a muscle disorder with "ragged red fibers." The condition is caused by a mutation in a mitochondrial gene. However, upon analyzing samples of various tissues for the mutation, researchers found that some cell types had the mutations, and others did not. Explain this finding.