Which of the following is NOT associated with mitochondrial disorders?

Mitochondrial disorders are a group of diseases caused by dysfunction in the mitochondria, which are the energy-producing structures in cells. The options provided include conditions that are associated with mitochondrial disorders, with one exception.

Myoclonic Epilepsy with Ragged Red Fibers (MERRF), pigmentary retinopathy, and Leber hereditary optic neuropathy (LHON) are all recognized conditions associated with mitochondrial dysfunction. MERRF involves seizures and myoclonus, as well as ragged red fibers observed in muscle tissue due to abnormal mitochondrial accumulation. Pigmentary retinopathy, characterized by degeneration of the retina that can lead to vision loss, is often seen in mitochondrial diseases. LHON specifically affects the optic nerve, leading to vision loss and is classically linked to mutations in mitochondrial DNA.

On the other hand, Down syndrome is a chromosomal disorder resulting from an extra copy of chromosome 21, known as trisomy 21. It is not a mitochondrial disorder and is primarily characterized by developmental delays, intellectual disabilities, and distinct physical features, but not by the dysfunctional energy production typically seen in mitochondrial diseases. Since Down syndrome is fundamentally different in its etiology, it does not belong in the group of conditions specifically