Classification of primary( hereditary and congenital) disturbances of intestinal absorption( a.f. frolkis)

I. Primary malabsorption of monosaccharides.

1. Primary malabsorption of glucose and galactose.

2. Primary malabsorption of fructose.

II.Primary disorders of absorption of amino acids.

1. Hartnap disease( 1: 26,000-1: 200,000).

2. Cystinuria( 1: 7000 newborns).

3. Congenital lisinuria( 1: 60,000 - 80,000 thousand).

4. Primary maltobsorption of tryptophan.

5. Imino-glycinuria( 1:15 000).

6. The syndrome of Loy.

7. Primary malabsorption of methionine.

III.Primary disorders of fat absorption.

1. A-betalapoproteinemia.

2. Primary malabsorption of bile acids.

IV.Primary disorders of absorption of vitamins.

1. Primary malabsorption of vitamin B12.

2. Primary malabsorption of folic acid.

V. Primary infringements of absorption of mineral substances.

1. Acrodermatitis is enteropathic.

2. Primary hypomagnesemia.

3. Menkes syndrome( 1: 35,000).

4. Family hypophosphatemic rickets.

5. Idiopathic primary hemochromatosis.

Hereditary disorders of absorption of amino acids must be distinguished from hereditary amino acid metabolism disorders, in which transport processes in the intestine do not suffer. The study of congenital disorders of amino acid transport in the small intestine made it possible to establish that these are quite diverse disorders. On the one hand, they can be mild and not accompanied by clinical symptoms, on the other hand, there may be quite severe, sometimes fatal disorders( Low syndrome, congenital lysinuria).There are good reasons to believe that under these pathological conditions there is a genetically programmed defect in the synthesis of the corresponding vectors.

It can be assumed that there are 4 transport systems and, consequently, the corresponding carriers:

1) for absorbing neutral amino acids( most amino acids);

2) for the absorption of basic amino acids( arginine, lysine, ornithine, cystine);

3) for the transport of acidic amino acids( aspartic, glutamine);

4) for the absorption of amino acids proline, hydroxyproline, sarazine, betaine and glycine. It is impossible to exclude and an independent system for the absorption of methionine. Apparently, there is also an independent mechanism for the transport of amino acids that make up peptides, which helps compensate for the genetic defect in certain diseases.

Of great importance is the fact that with the primary pathology of absorption of amino acids in most cases, there is a defect in the transport of these substances in the kidneys. At the same time there is an increased loss of certain amino acids by urine.

In most hereditary defects of the small intestine absorption function, the anomalous gene is localized in one or the other of the 22 autosomes. In some pathological conditions( Menkes syndrome, familial hypophos-phatemic rickets), the abnormal gene is localized in the sex X chromosome, i.e., an anomaly is associated with the sex, with impairment of absorption clinically manifested mainly in males, and in females- only in cases where an abnormal gene is present in both X chromosomes.

Most of the hereditary intestinal absorption disorders are inherited by the recessive type. This inheritance indicates that clinical manifestations of the disease and pronounced biochemical changes occur in individuals who are homozygous for this abnormal gene. Heterozygotes with only one anomalous gene from the pair and one normal gene are usually practically healthy, although they may have latent( latent) biochemical shifts. Among parents of such children, related marriages are more common than in the population.

The cause of primary disturbances of the small intestine absorption function are genetically caused disorders of the molecular mechanisms of intestinal transport of nutrients. Changes in the structure of the small intestine mucosa, observed in some forms of such disorders( Loy syndrome, lethal family protracted diarrhea, abetalipoproteinemia, enteropathic acrodermatitis), develop again against the background of existing disorders.

The presence of selective( selective) intestinal absorption disorders is the most important confirmation of the existence of independent transport systems for certain substances( glucose, galactose, fructose, various amino acids, fats, bile acids, vitamin B12, zinc, magnesium, copper, phosphates, electrolytes).The existence of general mechanisms of transport in the intestines and kidneys is evidenced not only by selective absorption disorders of amino acids, but also by other forms of primary malabsorption( malabsorption of glucose and galactose, hypophosphatemic rickets), where transport disorders in the small intestine and in the kidneys are observed.

At present, chromium, copper, cobalt, manganese, molybdenum, selenium and zinc are considered irreplaceable for human food elements. It is known that the overall physiological role of microelements is determined by their connection with the enzyme systems in the cell. Microelements ensure the stability of the spatial structure of protein molecules in the body, which gives it greater vitality and reactivity. Metals are part of the enzymes and their complexes. Thus, microelements are vital for the synthesis of all proteins in the human body.