Argininyantarnaya acidura
The disease was first described in 1958. It is transmitted by an autosomal recessive type of inheritance.
The primary biochemical defect in this type of protein metabolism disturbance is the inadequacy of the enzyme activity that provides the formation of the amino acid arginine from arginine succinic acid. This enzyme can be located in such organs and tissues as the liver, kidneys, small intestine, erythrocytes, as well as skin cells.
The degree of severity of the disease can range from mild to extremely severe, up to a lethal outcome in the first month of life of the child. Those symptoms that appear in a child with this impairment of amino acid metabolism are mainly due to intoxication with substances such as ammonia and arginine succinic acid, which accumulate in the body in excess. Deterioration of the condition with arginine-ventricular aciduria often develops after a meal rich in protein.
Depending on the timing of the appearance of the first signs and the nature of the course of the disease, two forms are distinguished: with acute symptoms in the first months of life and with a later manifestation of metabolic disorders.
Arginine-succinic aciduria with an early onset is characterized by a fast-progressive course and in most cases ends lethal. After a short asymptomatic period, the child begins to refuse to eat, the body weight decreases. Soon after that, the newborn becomes drowsy, signs of central nervous system depression appear, which ultimately leads to the development of coma. Quite often, there are various disorders of breathing, muscle tone decreases, convulsions, vomiting appear. When the examination reveals an increase in the size of the liver. The reason for the death of a child with this form of arginine-mandaric aciduria is the stopping of breathing and the heart, which occurs in the first weeks of life. In extremely rare cases, the first manifestations of the disease can appear at the age of up to 1 month of the child's life, but there is no lethal outcome. In such a course of the disease, the first symptoms in children appear in the form of a severe metabolic disorder, which is manifested by a violation of breathing( it becomes rapid, superficial, pathological breathing may appear: the child makes several breaths that become less deep, then within a minute there is no breath at all,and then appears again, with the depth of breathing gradually increasing, then everything repeats again), cardiac activity( the rapidity of the pulse, it becomes unstable, then it can comeslowing), child's mind( it becomes stalled or, conversely, overly excitable, then comes fainting or even coma).Usually such a picture develops in 1-2 weeks of life. In the future, such states are periodically repeated, which ultimately leads to a child's lag in psychomotor development from his peers.
The second form of arginine-succinic aciduria is characterized by a later appearance of characteristic symptoms, in early childhood( 1-3 years), and less severe course of the disease. At the forefront with this form of disease, signs of damage to the nervous system. Such a child can notice the appearance of seizures, it begins to progressively lag behind in the psychomotor development, periodically there may be violations of coordination of movements( "drunken gait", trembling of fingers, the child misses when trying to touch the tip of the finger to the tip of the nose, etc.).The hair of these children is dry and brittle, muscle tone is reduced. At the examination in a medical institution, an increase in liver size is revealed. In the literature, there are descriptions of several children with arginine-mandaric aciduria, who have retained normal intelligence.
In the study of blood and urine, a large amount of arginine succinic acid, as well as ammonia and its compounds, is detected, which arises as a result of excessive accumulation in the body.
Treatment of is mainly to maintain a diet based on limiting the amount of food rich in protein. The appointment of diet therapy requires the development of an individual diet and diet for each sick child. In addition, the child should be under control, which is carried out by the systematic method of determining the content of arginine succinic acid and ammonia in the blood and urine. Against the background of compliance with a low-protein diet, additional administration of arginine-succinic acid is advisable, the amount of which, against a background of the diet, is reduced to extremely low values.