Known as the powerhouse of the cell mitochondria are responsible for providing energy to any living cell. The presence of mitochondria in a cell is usually seen as a sign of evolution and both plants and animals have mitochondria as a part of their cells. In fact the reason why viruses are considered half living and half dead is because they lack basic cellular structures like mitochondria. Mitochondrial diseases usually occur due to impaired mitochondrial functioning resulting from defective DNA present in the mitochondria. However before we discuss diseases it is important to know how mitochondria actually multiply and inherit DNA.
Just like every cell in the body has DNA similarly mitochondria too has DNA. The first thing to remember is that mitochondria have lesser DNA information stored in them and all the DNA present in mitochondria is inherited from the mother. When mitochondria divide the DNA present in the original mitochondria is distributed randomly into the new mitochondria, this means that a genetic defect can actually be amplified through random divisions and over a period of time the number of mitochondria with defective DNA can increase. Mitochondrial diseases usually occur when the number of mitochondria with defective DNA in the body or a particular organ is high; this is known as "threshold expression".
The good news is that mitochondria do not carry out all cellular functions of the body and it is possible for a cell to survive even with defective mitochondrial DNA, however when the number of defective mitochondria is large the organ that has defective mitochondria is impaired. In fact this is why expression of mitochondrial diseases is different in different people; the defect maybe the same but the part of the body that is affected can be different. The above stated fact makes diagnosis of mitochondrial diseases very difficult. More often than not it takes more than just one test or diagnosis to confirm mitochondrial diseases.
Mitochondrial diseases are usually expressed in a variety of ways like seizures, muscle wasting, low blood sugar etc. People suffering from mitochondrial diseases usually exhibit more than one symptom and hence the diagnosis of such a person is difficult. Since the mitochondria are responsible for providing energy to a cell, if the defective mitochondria are present in the nerves or muscles the effects are more severe. Patients with mitochondrial conditions that affect the nerves or muscles usually have poor co-ordination and exhibit poor muscular control and muscle wasting.
Since the symptoms of mitochondrial diseases are very diverse it is not easy to classify all patients into a single group, however there are a few symptoms that are usually associated with mitochondrial diseases. A patient suffering from mitochondrial disease can exhibit dementia, hypoglycaemia, muscle wasting, seizures, diabetes and other generic symptoms. In fact it requires considerable expertise to diagnose a patient with mitochondrial disease, since there is no single test or genetic marker that can pin point to mitochondrial disease the diagnosis of mitochondrial disease is usually a combination of tests and symptoms that a patient exhibits.
Diagnosis of Mitochondrial diseases
Unlike cancer and other diseases, there is no known marker test or set pattern that can help in diagnosing mitochondrial diseases. Diagnosis of mitochondrial diseases is purely based on the symptoms that a patient exhibits. Since mitochondrial diseases actually have different symptoms depending on the body organ that is affected sometime diagnosis of mitochondrial diseases can take weeks or months. Another problem with effective diagnosis of mitochondrial disease is that usually patients show improvement for a limited period of time when the symptoms are treated. Usually it takes more than one symptom of mitochondrial disease to develop to help in pin pointing the symptoms to mitochondrial diseases. In most cases blood tests and genetic tests usually help in effective diagnosis of mitochondrial diseases.
Greg Cavlovic is the author of this article on Donation.
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