A 6-year-old boy is brought to his pediatrician because his parents are concerned about the appearance of seizures and stroke-like episodes. Upon examination the parents reveal that their son has recently begun to exhibit a progressive incoordination in his walking and also difficulty picking up his toys. The physician notes that the patient is short for his age and an eye examination reveals pigmentary retinopathy. Analysis of blood shows elevated levels of lactic acid. These signs and symptoms are most indicative of which of the following disorders?

Question

Quizplus · Accepted Answer

The symptoms described, including seizures, stroke-like episodes, progressive incoordination, short stature, pigmentary retinopathy, and elevated lactic acid levels, are characteristic of MELAS syndrome, a mitochondrial disorder.  Mitochondrial biogenesis disorders are similar to lysosomal storage diseases in that there are symptom similarities between several different diseases of the class. Many of the mitochondrial encephalomyopathies are associated with hearing loss, vision problems such as pigmentary retinopathy, and neurological dysfunction. MELAS is characterized by the fact that it is also associated with the potential for severe lactic acidosis stroke-like episodes. Leigh syndrome is normally fatal before age 5 and so could be eliminated solely on the basis of the patient's age.

A 6-Year-Old Boy Is Brought to His Pediatrician Because His