Hereditary metabolic diseases

August 12, 2017 17:51 | Genetic Diseases

among human hereditary diseases is one of the most important places occupied by hereditary metabolic disease.This is a fairly large group of diseases that includes about 700 different diseases.For 200 of them are currently installed proximate cause, t. E. A genetic mutation and its location in the human chromosome.Most of the metabolic disorder is a congenital deficiency of a certain enzyme, which is the cause of a genetic mutation.When he or deficiency of the enzyme is not formed in the human body at all or is formed, but differs from the normal low activity that leads to metabolism disorders.The enzyme is a substance which can not without various chemical reactions occur which form the basis of metabolism.Loss of this enzyme function creates a block in the corresponding chemical reaction.As a result, accumulation of metabolites observed immediately preceding block, and final reaction products deficiency;metabolic block can also lead to disruption of separate transport connections.

accumulate to block

chemicals are often toxic.Thus, when a specific enzyme deficiency in the blood and tissue accumulates not only the amino acid phenylalanine, but also phenylpyruvic acid, has a toxic effect on the baby's brain at such disease as phenylketonuria.Hereditary disorders urea synthesis may result in accumulation in the blood and tissues of ammonia, which is also accompanied by a toxic central nervous system.

Many diseases are caused by deficiency of end products of metabolism, stopped as a result of a specific unit.An example is the synthesis of hormones hereditary disease (congenital adrenal hyperplasia, hypothyroidism, hypoparathyroidism).

A number of inherited metabolic diseases caused by lack of vitamins in the body.In some cases, the absence or reduction of the corresponding enzyme activity can be partially restored by administration of high doses of vitamin.These metabolic disorders are known as congenital vitaminzavisimyh.As a result of a genetic mutation formation of the enzyme is completely broken or formed with impaired enzyme structure, devoid of its activity, the introduction of high doses of vitamin does not give any effect.Such infringements of deception are called vitaminrezistentnyh (resistant to the introduction of vitamins) congenital disorders.

reason for a number of inherited metabolic diseases may be micronutrient deficiencies.More than 180 enzymes of the human body are metalloproteins, t. E. Are composed of molecules or metal ions.Such metals include, for example, copper, zinc, manganese, magnesium, molybdenum, cobalt, selenium.Micronutrient deficiency may be due to the peculiarities of the environment in which a person lives, although in most cases it is often associated with impaired absorption or transport of metals in the body.

Most of all hereditary disease is inherited in a recessive exchange (autosomal or clutch X-linked) type.Dominant inheritance is very rare.

There are various classifications NBO - the type of inheritance, by the nature of metabolic disorders and others, but none of them is not exhaustive and does not fully reflect the whole complex set of this pathology.

detection of hereditary metabolic diseases of emerging symptoms is quite difficult.Modifying enzyme activity causes various disorders of metabolism, which leads to a wide variety of symptoms.In some cases, signs of emerging disease in humans may be associated with very severe disease and lead to death even in the neonatal period, some lead to permanent mental retardation and disability.Sometimes sharing violations are accompanied by less severe symptoms or proceed with a complete lack of them.

Despite the variety of symptoms of hereditary metabolic diseases can be identified common features, on the basis of which it is possible to draw conclusions about the presence of abnormalities in the baby.These characteristics include: mental retardation, disorders of the nervous system, repeated convulsions and coma, the specific smell of urine and body (sweaty feet, cat urine, mouse smell, the smell of maple syrup), loss of muscle, skeletal abnormalities, changes in hair andskin, cataracts, enlarged liver and spleen, indigestion, unexplained death of the brothers (sisters).Many hereditary diseases exchange occur in the neonatal period, but seldom recognized.This is due to the fact that the deviations in the child's state of health is often considered by doctors as a consequence of oxygen deficiency during pregnancy and intracranial birth trauma.A distinctive feature of hereditary diseases in newborns is the presence of an asymptomatic period that can last for 2-3 days after birth.Children are born apparently healthy, but their condition worsens suddenly.

various metabolic diseases rarely have the characteristics, but in humans, symptoms can be grouped into two basic groups: toxic type and gipoenergeticheskogo type.brain damage such as toxic due to the accumulation in the body of toxic metabolic products.These may be organic acids, ammonia, and many other substances.Common manifestations of toxic lesions are: the rejection of the chest, vomiting, lethargy and coma, convulsions, respiratory failure, muscle and kidney failure, hypertension, muscle clonus, the loss of large amounts of fluid.brain lesions characterized gipoenergeticheskogo type or depletion of energy reserves, or inability to use by the body.This type of destruction is manifested the same symptoms (vomiting, lethargy, coma), but with a marked decrease in muscle tone, reduction or complete absence of reflexes, heart lesions, vascular insufficiency, syncope, and even sudden death.

Early diagnosis of hereditary metabolic diseases before the appearance of characteristic symptoms, the presence of which mention the irreversibility of processes in the human body, it is necessary first of all to the timely correction of metabolic disorders, as well as to prevent possible dangerous consequences.To this end, in recent decades, widespread program sieving (screening).They are used to identify the population of certain types of hereditary metabolic diseases.Mass examined all newborns, as well as those of the special risk groups such as children with various developmental disorders.Screening programs include two stages.At the first stage the alleged individual patients or carriers of hereditary metabolic diseases, on the second - a more complete examination and a final recognition of the disease.In modern mass screening programs are mainly used methods of determining the abnormal blood exchange products.

There are a number of criteria for the selection of certain diseases like sifting the exchange object:

1) the disease to be quite common in a population at a frequency of at least 1: 100 000 live births;

2) disease without timely detection and treatment can lead to serious health disorders;

3) there are ways to treat the disease;

4) have adequate diagnostic tests to detect;

5) costs of screening programs do not exceed the funds needed to service this category of patients.

Given these criteria, it was recognized that mass screening is necessary to detect phenylketonuria, hypothyroidism, adrenogenital syndrome, galactosemia and other metabolic diseases.

survey of individual risk groups, especially children who are lagging behind in psychomotor and physical development, it is necessary to prevent serious consequences of metabolic diseases.Timely detection of the disease contributes to, in addition to the prevention of disability in children;effective genetic counseling of families surveyed, which prevents the spread of disease in the family and society.

now been developed principles of treatment of hereditary metabolic diseases.They include the following items:

1) compliance with the specific diet in order to eliminate from the diet products containing the substance is not completely digested and subsequent transformations occurring in a healthy body.This eliminates the accumulation of toxic substances;

2) the introduction of the missing exchange regulators (hormones, vitamin B6, B12, etc.)..;

3) substitution of the missing enzymes;

4) transplantation of organs and tissues (kidney, bone marrow, heart);

5) to eliminate or limit the influence of adverse factors of the environment (elimination of solar irradiation in diseases with increased skin sensitivity or distorted, seizure medications exacerbate metabolic disorders);

6) specific treatments.

Drug treatment of mental retardation in hereditary diseases of metabolism involves the use of stimulants of the central nervous system.They improve metabolic processes in nerve tissue and play a major role in the development of mental and speech and motor development of children.In the complex treatment of a great role for vitamins.When hereditary metabolic diseases of the endocrine system are often used respective hormones.In violation of the formation of bone tissue is highly hormonal drugs in combination with calcium supplementation, phosphorus, B vitamins, citrate, antioxidants.

In the prevention of hereditary diseases of metabolism play a special role of prenatal diagnosis.The objects of study in this case are either chorionic cells in the 7-9 week of pregnancy, or amniotic fluid taken for analysis at 16-17 weeks of gestation.Currently, prenatal diagnosis is possible when more than 60 different inherited metabolic diseases.