Melas (mitochondrial encephalopathy, lactic acidosis and stroke episodes) (Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) - Genes MT-ND1, MT-ND5, MT-TH, MT-TL1, MT-TV.
MELAS syndrome, is a process that affects many organs, especially the central nervous system (encephalopathy) and muscles (myopathy). Signs and symptoms usually appear in childhood, but not exclusively, after a period of normal development. Initial symptoms include muscle weakness and pain, recurrent headaches, anorexia, vomiting and seizures. Most of those affected suffer from episodes of cerebral ischemia that begin before age 40, manifesting as transient episodes of muscle weakness on one side of the body (hemiparesis), perceptual disturbances, visual abnormalities, seizures and severe headaches.
Most people affected by the disease have lactic acidosis resulting in vomiting, abdominal pain, fatigue, muscle weakness and difficulty breathing. Less often, lactic acidosis results myoclonus, ataxia, hearing loss, heart and kidney disorders, diabetes and hormonal imbalances.
This syndrome is the result of mutations in certain genes of mitochondrial DNA (MT-ND1, MT-ND5, MT-TH, MT-TL1, MT-TV) found in the mitochondria (mitochondrial DNA, mtDNA). Some of these genes encode proteins involved in normal mitochondrial function. These proteins are part of a large enzyme complex in mitochondria that helps convert oxygen, fats and simple carbohydrates into energy. Other genes associated with the disease, molecules encoding transfer RNA (tRNA). These molecules help assemble amino acids to synthesize proteins into the mitochondria.
Mutations in MELAS related genes, nucleotide change in the gene, altering the ability of mitochondria to encode proteins, using oxygen and energy. It is unclear how changes in mitochondrial DNA leads to the signs and symptoms of MELAS. It is investigating the effects of mutations in mitochondrial genes different tissues, particularly the brain. A mutation in the MT-TL1 gene responsible for over 80% of cases of this syndrome replaces guanine adenine nucleotide by nucleotide at position 3243 (A3243G). In the MT-ND5 gene, a known mutation replaces guanine nucleotide with the adenine nucleotide at position 13513 (G13513A). In the MT-TV gene, they have been identified two mutations each of which alters a single nucleotide in the gene. One of these mutations replaces guanine nucleotide with the adenine nucleotide at position 1642 of the gene (G1642A). Another mutation changes the guanine nucleotide by adenine nucleotide at position 1644 (G1644A).
The MELAS syndrome is inherited mitochondrial or maternal pattern, since it is the egg, not the sperm, which contributes mitochondria to the future embryo. However, they can be affected both sexes, but only the mother through the egg, transmits it to the offspring. Mitochondrial disorders can appear in each generation of a family and can affect both men and women, but parents do not pass mitochondrial traits to their children. In most cases, people with MELAS syndrome inherit an altered mitochondrial gene from his mother. Less commonly, disruption is caused by a new mutation in a mitochondrial gene and occur in people with no family history of the disease.
Tests in IVAMI: in IVAMI perform the detection of mutations associated with MELAS syndrome by complete PCR amplification of the exons of the MT-ND1, MT-ND5, MT-TH, MT-TL1, MT-TV genes, respectively and subsequent sequencing.
Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).