It is known that with the development of genetics, many congenital pathologies were discovered. Changing chromosomes can cause a wide variety of abnormalities. Some of them are noticeable immediately after the birth of the child, others are manifested in childhood or adulthood. Kearns-Sayre syndrome refers to pathologies of mitochondrial DNA. It combines 3 symptoms, the relationship between which was discovered only by the end of the 20th century. Mitochondrial diseases are a large group of genetic pathologies that are laid during the period of intrauterine development and are transmitted through the maternal line. This type of anomaly was discovered due to the development of genetics.
Kearns-Sayre Syndrome: Description
Diseases of mitochondrial DNA imply tissue respiration, which occurs at the biochemical level. As a result, the symptoms of these pathologies may be different. Kearns-Sayre syndrome belongs to the group of mitochondrial diseases in which a deletion of chromosomes occurs. It was first described in 1958. At that time, the scientist Cairns gave only 9 examples of incidence. The main symptoms of this pathology are progressive ophthalmoplegia, retinopathy and intracardiac block. The disease occurs with the same frequency in both boys and girls. However, only women can be carriers of a damaged chromosome. This pathology refers to very rare anomalies; at the moment, about 200 cases have been recorded worldwide.
Causes of Kearns-Sayre Syndrome
Like all mitochondrial diseases, this syndrome has been studied not so long ago. Therefore, the exact reasons for its development are not known. It is believed that the anomaly is formed in the first trimester of pregnancy, when the laying of tissues and genetic material inherited from parents occurs. The basis of the disease is a deletion of the chromosome, that is, the loss of its part from the DNA chain. In addition, in some patients there is duplication (doubling) of the D-loop. Carriers of these genetic changes can only be women. This is due to the fact that mitochondrial chains are present only in the composition of the egg cells. Nevertheless, it is impossible to establish exactly what triggers the process of deletion of chromosomes. Like all congenital pathologies, diseases are associated with exposure to harmful environmental factors. These include: stress experienced in the first month of pregnancy, chemical poisoning, smoking, alcoholism and drug use.
The clinical picture of the disease
Kearns-Sayre Syndrome is characterized by three classic symptoms. Among them:
- Progressive ophthalmoplegia. It develops due to damage to certain muscles that are responsible for the movements of the eyeball and upper eyelid. For the same reason, another symptom is observed - unilateral ptosis. Most often, this is the first sign that makes itself felt. Later, muscles in the other eye begin to be affected. Gradually, due to ptosis and ophthalmoplegia, the field of vision decreases more and more, and a person has to bend or throw his head back to see.
- Retinopathy retinopathy. This symptom is characterized by the appearance of spots on the retina. If you examine the eye center (bottom) using a special device, then you can see the common pigmentation. Unlike retinitis, the center is most colored - a yellow spot. As a result of pigmentation in some patients there is a symptom of "night blindness" and a decrease in visual acuity.
- Intracardiac block. This symptom develops later than the rest. Most often, conduction is disturbed in the AV node, which is characterized by bradycardia, rapid fatigue and intolerance to loads. With 3 degrees of blockade, convulsions and a fainting state can occur .
Diagnostic criteria for Kearns-Sayre syndrome
Diagnosis of Kearns-Sayre syndrome is based on clinical and laboratory-instrumental data. The disease develops in childhood or adolescence (up to 20 years) and has a progressive course. In addition to the classic symptoms, other manifestations of the pathology can be observed. Among them: cerebellar ataxia, deafness, facial muscle weakness , decreased intelligence. Instrumental examinations necessary for this syndrome: ECG and echocardiography, ophthalmoscopy. To make an accurate diagnosis, you need the conclusion of an ophthalmologist, cardiologist and genetics.
Cairns-Sayre Syndrome Treatment
To date, the development of etiological treatment of this disease is underway. Some studies describe the effectiveness of Coenzyme Q10, which normalizes the level of lactic and pyruvic acids. All patients with Cairns-Sayre Syndrome need symptomatic treatment. It is mainly aimed at eliminating heart block. In case of bradycardia, Atropine is prescribed, if there is a convulsive syndrome - Diazepam medication. In most cases, the patient needs a pacemaker. Surgery is necessary for the treatment of ptosis, ophthalmoplegia and retinopathy retinopathy.