Concepts of Genetics 11th Edition by William Klug,Michael Cummings,Charlotte Spencer,Michael Palladino

Exercise 2

In 2000, Rocco Baldelli was a first-round draft pick by the Tampa Bay Rays baseball team. Two years later, his early success in professional baseball was followed by disabling muscle injuries and fatigue. His mysterious illness was traced to a disorder called mitochondrial myopathy. This diagnosis brought not only personal clarification to one set of identical twin brothers, but also national awareness of an array of similar disorders that affect thousands of children and adults regardless of age, gender, race, or position in society. For 14 years the twin brothers competed on equal terms until Rocco began to suffer loss of visual acuity and muscularity. Diagnosis of a mitochondrial disorder explained the cause and forecasted supportive treatment, but also raised some important questions.
How could one identical twin have an inherited mitochondrial disorder and not the other?