Epilepsia mioclónica con fibras rojas rasgadas (MERRF)

Myoclonic epilepsy with ragged red fibers (MERRF) is a multisystem disorder characterized by myoclonus, which is often the first symptom, followed by generalized epilepsy, ataxia, weakness, and dementia. Symptoms usually first appear in childhood or adolescence after normal early development. The features of MERRF vary widely from individual to individual, even within families. Other common findings include hearing loss, short stature, optic atrophy, and cardiomyopathy with Wolff-Parkinson-White (WPW) syndrome. The diagnosis is based on clinical features and a muscle biopsy finding of ragged red fibers (RRF). In over 80% of cases, MERRF is caused by genetic changes in the mitochondrial gene called MT-TK. Several other mitochondrial genes have also been reported to cause MERRF, but many of the individuals with genetic changes in these other genes have additional signs and symptoms. Coenzyme Q10 and L-carnitine are often used with the hope of improving mitochondrial function.

Genetic Mutations: MERRF is caused by genetic mutations, also known as pathogenic variants. Genetic mutations can be hereditary, when parents pass them down to their children, or they may occur randomly when cells are dividing. Genetic mutations may also result from contracted viruses, environmental factors, such as UV radiation from sunlight exposure, or a combination of any of these.

Si sospecha que puede tener esta enfermedad, se recomienda que empiece a recopilar el historial de salud de su familia. Debe comentar con su equipo médico cualquier información sobre otros familiares que hayan tenido síntomas similares, cuándo aparecieron por primera vez dichos síntomas (en usted o en sus parientes) o la exposición a factores ambientales que pudieran, potencialmente, causar la enfermedad.

Known Genetic Mutations: MERRF is caused by genetic mutations in the following known gene(s):

TRNL1, TRNS1, MT-TF, TRNH, TRNP, ND5, TRNK

Dadas las mutaciones genéticas conocidas de esta enfermedad, se recomienda que pregunte a su equipo de atención médica si las pruebas genéticas son adecuadas para usted. Las pruebas genéticas son exámenes de laboratorio de muestras de sangre, saliva u otros tejidos para ayudar a identificar cambios en genes, cromosomas o proteínas. Las pruebas genéticas pueden confirmar o descartar una posible enfermedad genética, o dar otra información útil a su equipo médico.

Disruption in Metabolism: MERRF is caused by a disruption in a person’s metabolism. Metabolism is the series of chemical reactions in our body that turns the food we eat into energy and removes toxins. Hormones and specific proteins, called enzymes, help make the right chemical reactions happen in the right order. However, genetic changes can prevent hormones or enzymes from working properly, which can lead to a disruption in metabolism such as energy not being created for the body or toxins not being removed from the body.

Impaired Mitochondrial Function: MERRF is caused by an impairment, or issue, in mitochondrial function. Mitochondria make the energy needed for cells to work properly. When mitochondria are unable to produce enough energy for a cell, the cell can become damaged or can die. Depending on the location and number of damaged cells, different organs and body systems can be affected.

Sí. Es posible que un progenitor biológico transmita a su hijo mutaciones genéticas que causen esta enfermedad o que aumenten las probabilidades de heredarla. Esto se conoce como herencia. Saber si otros miembros de la familia han tenido previamente esta enfermedad o, dicho de otro modo, el historial de salud de su familia, puede ser una información muy importante para su equipo médico.

Existen diversas formas o patrones en los que una enfermedad puede heredarse en función del gen o los genes implicados. A partir de los datos actuales del GARD, esta enfermedad puede heredarse según los siguientes patrones:

Herencia mitocondrial: la herencia mitocondrial significa que la mutación genética se produce en un tipo específico de ADN, el llamado ADNmt. El ADNmt se encuentra dentro de las mitocondrias de la célula. Las mitocondrias son estructuras diminutas que producen energía para el organismo. Las mutaciones genéticas en el interior del ADNmt pueden impedir que las mitocondrias funcionen correctamente.

During human conception, egg cells, or the cells that come from the female parent, provide mitochondria. If a female parent is affected by a mitochondrial genetic mutation, there is a 100% chance their child inherits the mutated gene. However, the child may or may not be affected by the disease. A male parent cannot pass mitochondrial genetic mutations to their children.