Glucose phosphoisomerase deficiency
Introduction
Introduction to glucose phosphate isomerase deficiency Glucose phosphate isomerase (GPI) deficiency is the fourth most common erythrocyte enzyme disease in addition to G-6-PD, PK, pyrimidine 5'-nucleotidase (P5'N) deficiency. basic knowledge The proportion of illness: 0.001% Susceptible population: newborns, also in infants and childhood Mode of infection: non-infectious Complications: mental retardation simple red cell aplastic anemia
Cause
Glucose phosphate isomerase deficiency etiology
(1) Causes of the disease
GPI deficiency is autosomal recessive, about half of the patients are homozygous, others are heterozygous or double heterozygotes, heterozygous patients without anemia, only enzyme activity is reduced, and homozygous (or double heterozygotes) are accompanied There is congenital non-spherical erythrocyte hemolytic anemia (HNDHA).
(two) pathogenesis
GPI protein is a dimer with a molecular weight of 134kD. The lack of GPI is characterized by heat instability, but the enzyme kinetics, optimum pH and molecular weight are normal. One patient has spleen and liver when cutting the spleen. Muscle, leukocyte and plasma GPI electrophoresis were found to have the same abnormal band as red blood cells, suggesting that there is no tissue-specific isoenzyme in GPI in various tissues, and the GPI gene is located at 19p. It is known that patients with GPI deficiency have significant Molecular heterogeneity, with GPI structural gene mutations and gene deletions.
The mechanism of hemolysis remains unclear. Compared with normal red blood cells of the same age, GPI deficiency accumulates 6-phosphate glucose in red blood cells, ATP and 2,3-DPG decrease, erythrocyte membrane deformability decreases and becomes particularly stiff, and Hb is in red blood cells. The membrane adheres very tightly, so reticulocytes and mature red blood cells are easily destroyed by the spleen.
Prevention
Glucose phosphate isomerase deficiency prevention
Attention should be paid to prevention, eugenics, pre-marital and prenatal examinations.
Complication
Glucose phosphate isomerase deficiency complications Complications, mental retardation, simple red blood cell aplastic anemia
Aplastic anemia and severe hemolytic crisis may occur due to infection or induction of certain drugs. In most cases, there is no other organ damage. Only individual cases are accompanied by mental retardation, low muscle tone, and hepatic glycogen accumulation.
Symptom
Glucose phosphate isomerase deficiency symptoms Common symptoms Jaundice edema
Hemolytic anemia, but the severity of the disease can be very different, severe cases can be caused by fetal edema syndrome, one third of the newborns have anemia and jaundice and need to change blood, but also in infants and childhood, can be accompanied There are mild to moderate splenomegaly, with or without liver enlargement, some require long-term blood transfusion due to severe anemia, and some can be fully compensated.
Examine
Examination of glucose phosphate isomerase deficiency
1. Peripheral blood: The morphological characteristics of red blood cells are uneven size, heterotypic, polytropic erythrocytosis, common nucleated red blood cells, reticulocyte count can be significantly increased (50% to 60%).
2. Red blood cell life is shortened, even only 4.5 days, self-hemolytic test increased with saline, partial correction can be obtained after adding glucose and ATP.
3. GPI deficiency can be screened by a fluorescent dot test, but it is determined that the GPI activity is still determined, and the homozygous and double heterozygous enzyme activities are reduced to about 25% of normal.
Diagnosis
Diagnosis and identification of glucose phosphate isomerase deficiency
According to family history, clinical manifestations and GPI activity measurements can be confirmed.
