Most patients will not exhibit all of these symptoms, but more than one of these symptoms will be present in a patient who has been diagnosed with MERRF disease. Mitochondrial disorders, including MERRF, may present at any age. Due to the multiple symptoms presented by the individual, the severity of the syndrome is very difficult to evaluate. Causes
The cause of MERRF disorder is due to mutations in the mitochondrial genome. This means that it is a pathological variant in mtDNA (mitochondrial DNA) and is transmitted by maternal inheritance. Four point mutations in the genome can be identified that are associated with MERRF: m.A8344G, m.T8356C, m.G8361A, and m.G8363A. The point mutation m.A8344G is most commonly associated with MERRF, in a study published by Paul Jose Lorenzoni from the Department of neurology at University of Panama stated that 80% of the patients with MERRF disease exhibited this point mutation. This point mutation disrupts the mitochondrial gene for tRNA-Lys. This disrupts the synthesis of proteins. The remaining mutations only account for 10% of cases, and the remaining 10% of the patients with MERRF did not have an identifiable mutation in the mitochondrial DNA.Many genes are involved. These genes include:

MT-TK
MT-TL1
MT-TH
MT-TS1
MT-TS2
MT-TFIt involves the following characteristics:

progressive myoclonic epilepsy
"Ragged Red Fibers" - clumps of diseased mitochondria accumulate in the subsarcolemmal region of the muscle fiber and appear as "Ragged Red Fibers" when muscle is stained with modified Gömöri trichrome stain.There is currently no cure for MERRF. Mechanism
The mechanism by which MERRFs syndrome occur is not yet well understood.
If the pain relates to the coccyx, this should produce immediate relief.If the anesthetic test proves positive, then a dynamic (sit/stand) x-ray or MRI scan may show whether the coccyx dislocates when the patient sits.Use of dynamic x-rays on 208 patients who gave positive results with the anesthetic test showed:

31% Not possible to identify the cause of pain
27% Hypermobility (excessive flexing of the coccyx forwards and upwards when sitting)
22% Posterior luxation (partial dislocation of the coccyx backwards when sitting)
14% Spicule (bony spur) on the coccyx
5%  Anterior luxation (partial dislocation of the coccyx forwards when sitting)This study found that the pattern of lesions was different depending on the obesity of the patients: obese patients were most likely to have posterior luxation of the coccyx, while thin patients were most likely to have coccygeal spicules. Angle of incidence
Sagittal coccygeal movement is measured using the angle of incidence—or the angle at which the coccyx strikes the seat when an individual sits down. A smaller angle indicates the coccyx being more parallel to the seat, resulting in flexion (or “normal” movement) of the coccyx. A larger angle indicates the coccyx being more perpendicular to the seat, causing posterior subluxation (or “backward” movement) of the coccyx. Causes
One way of classifying coccydynia is whether the onset was traumatic versus non-traumatic. In many cases the exact cause is unknown and is referred to as idiopathic coccydynia. Coccydynia is a fairly common injury which can often result from falls, particularly in leisure activities such as cycling and skateboarding.