Melas syndrome otherwise known as mitochondrial encephalopathy is a rare disorder affecting the muscles and nervous system. The symptoms of this disorder begin as early as childhood and the signs become evident before the person attains 15 years. It can cause seizures, intense headaches and muscle weakness leading to loss of vision and hearing. For some children it may cause one side paralysis. This syndrome is caused due to defective mutation of mitochondrial DNA. No treatment is available for MELAS syndrome.
MELAS Syndrome Causes :
The DNA material involved in the making of mitochondria undergoes repeated mutation. Hence MELAS syndrome is a genetic disorder inherited by birth. Mitochondria are particles found in the cytoplasm of the cell. The mitochondria contain a chromosome (different from the regular chromosomes present in the nucleus) which is very small and round in shape. Mitochondrial chromosomes are always inherited from the other since during fertilization MtDNA obtained from the father is lost. Hence this disorder is passed on to the children from the mother.
Defective mutations of the mitochondrial chromosome cause this disorder. Affected mother would pass on the MtDNA to all her children however only the daughters would pass it on to the next generation. In some cases both normal and defective MtDNA are present in the same cell but the number of defective Mt may be large.
MELAS Syndrome Symptoms :
Signs of MELAS syndrome become evident between 2-15 years of age. In more than 75% of the cases symptoms of this disorder begin before 20 years. Not all the individuals with MELAS would have the same symptoms and it may differ in affected children of the same family also. This disorder is characterized with stroke like episodes and seizures. This can occur due to deficiency of nitric oxide in the blood vessels of the brain. In many cases loss of hearing, loss of vision can occur. Due to defective muscular growth, the person may be very short in structure.