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The brain's secret crisis: How MELAS causes stroke-like attacks and epilepsy?
MELAS (mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes) is a rare genetic disorder that is part of a family of mitochondrial diseases that also includes maternally inherited diabetes and deafness (MIDD), MERRF syndrome, and Leber inheritance Sexual optic neuropathy. These diseases are caused by defects in maternally inherited mitochondrial genes, which are often inconsistent with healthy genetic structure. MELAS was first diagnosed and named in 1984.
The signature mutation of MELAS is m.3243A>G, which is the most common form of mitochondrial DNA mutation.
Symptoms and signs
MELAS typically affects multiple systems, but the most significant effects are on the brain and nervous system and the muscular system. In most cases, children develop symptoms between the ages of 2 and 10, and development is usually normal until then. Patients may experience recurring migraines, loss of appetite, vomiting, and seizures. Additionally, lactic acid buildup in the body can cause lactic acidosis, which can lead to conditions such as extreme fatigue, muscle weakness, and difficulty breathing.
Different diagnosis
The symptoms of MELAS may be similar to those of Kearns–Sayre syndrome and MERRF syndrome, so careful attention is needed. Each of these diseases has its own characteristics, but symptoms such as epilepsy and muscle spasms are common to many mitochondrial diseases.
Basics of genetics
MELAS is mostly caused by genetic mutations in mitochondrial DNA, and may also involve mutations in nuclear DNA. Some genes like MT-ND1 and MT-ND5 are related to NADH dehydrogenase, while MT-TH, MT-TL1 and MT-TV are related to specific mitochondrial transfer RNAs. These mutations affect the ability of mitochondria to generate energy, leading to clinical symptoms.
Researchers are continuing to investigate how mutations cause the specific symptoms of MELAS, particularly in the brain.
Heredity
MELAS is passed down through the maternal line. The conceived fertilized egg comes from the mother's mitochondria, and the father's sperm does not pass on this trait. This means that the disease can appear in every generation and can affect both men and women, but fathers cannot pass mitochondrial traits on to their children. In most cases, MELAS patients inherit the mutated gene from their mother.
Diagnosis process
The process of diagnosing MELAS usually involves MRI scans, lactate level testing and genetic testing. MRI often shows multifocal infarct-like areas forming in different parts of the cortex, and elevated lactate levels are another key indicator. Due to the heterogeneity of mitochondria, urine testing and blood testing are critical to the accuracy of diagnostic results.
Treatment Plan
Currently, there is no cure for MELAS, and the disease course can be progressive and fatal. Treatment is primarily symptomatic based on the affected body part. For support of mitochondrial function, patients can receive a variety of enzyme, amino acid, and antioxidant supplements, among which coenzyme Q10 and vitamin B complex are considered to be potentially helpful supplements.
Epidemiology
The exact incidence of MELAS is unknown, but it is relatively common in a group of diseases called mitochondrial diseases, which affects about one in 4,000 people.
As awareness of this disease increases, early diagnosis and intervention are key to potentially saving lives.
For MELAS and related mitochondrial diseases, can future research enable us to better understand these hidden crises and bring hope to patients?
