Hemoglobin M disease
Introduction
Introduction to hemoglobin M disease Hemoglobin M disease is a methemoglobin caused by a change in the amino acid composition of the globin chain. The blood of patients with hemoglobin M disease is dark brown. The patient has no congenital heart disease, but has had a cyanosis since childhood. This hair lice has nothing to do with self-work. basic knowledge The proportion of sickness: 0.00017%--0.00028% Susceptible people: children Mode of infection: non-infectious Complications: hemolytic anemia
Cause
Cause of hemoglobin M disease
Cause:
The disease is caused by mutation of the globin gene and is an autosomal dominant genetic disease. Therefore, it is also called "familial purpura", and all of them are heterozygous.
(two) pathogenesis
Hemoglobin transports oxygen in iron-dependent hemoglobin in a reduced state (ferrous iron). When iron is oxidized to a high-iron state (ferric iron), hemoglobin becomes methemoglobin and cannot bind oxygen. Under physiological conditions, methemoglobin only accounts for hemoglobin. Below 0.01, when the methemoglobin content is >0.01, cyanosis occurs; >0.25 occurs clinical symptoms; >0.80 can cause death, and the globin chain amino acid variation of the disease occurs mostly in the position related to heme, for example with The histidine adjacent to heme is replaced by tyrosine, the hydroxyl group of tyrosine stabilizes iron in the trivalent state, and resists the methemoglobin reductase system, resulting in the formation of methemoglobin (hemoglobin M), in addition to hemoglobin M, clinical There are two main reasons for the cyanosis caused by methemoglobin: methemoglobin reductase deficiency and drugs, chemical-induced methemoglobin, the pathogenesis is different from this disease.
Prevention
Hemoglobin M disease prevention
Timely detection of timely treatment, usually eat more foods with high vitamin content. Because hemoglobin M disease is a genetic mutation, it can be considered from an environmental perspective. The impact of the environment on phenotypes, various environmental factors and even less care will have a certain impact on your phenotype (that is, traits). Note: This effect is not necessarily negative. It may be a manifestation of adapting to the environment. If you prevent harmful genetic mutations, you need to pay attention to the usual living environment, try to live in a place with less noise, radiation, pollution, good habits and habits must be developed, in order to effectively reduce the probability of genetic mutation.
Complication
Hemoglobin M disease complications Complications hemolytic anemia
The complication of hemoglobin M disease is hemolytic anemia. Hemolytic anemia refers to an anemia that occurs when red blood cell destruction is accelerated and bone marrow hematopoietic function is insufficiently compensated. If the bone marrow can increase erythropoiesis and is sufficient to compensate for the shortened survival of red blood cells, no anemia will occur. This state is called compensatory hemolysis.
Symptom
Hemoglobin M disease symptoms common symptoms cyanosis hemolysis
Mainly manifested as cyanosis, common in respiratory obstruction, severe pneumonia, pulmonary congestion, pulmonary edema, massive pleural effusion, spontaneous pneumothorax, etc.; can also be seen in systemic congestion, peripheral blood perfusion, local blood circulation disorders, such as right heart Failure, severe shock, thromboangiitis, cold stimulation, etc. Other clinical manifestations were not obvious. Taking oxidants (such as sulfonamides) can make your symptoms worse.
Examine
Examination of hemoglobin M disease
The absorption spectrum of hemoglobin M on the spectrophotometer is different from that of oxygenated HbA and other methemoglobin. Hemoglobin M and HbA can also be separated by pH 7.0 buffer hemoglobin electrophoresis. Hemoglobin electrophoresis globin-producing anemia is one of the most common and most common single-gene genetic diseases in the world. There are two common types, namely and marine anemia (formerly known as thalassemia), which are caused by genetic mutations. Several hemoglobin (Hb) synthesis in red blood cells is abnormal. This test can be used to test abnormal Hb and further diagnose some related diseases.
Diagnosis
Diagnosis and identification of hemoglobin M disease
Hemoglobin M disease should be differentiated from hereditary methemoglobinemia:
Hereditary methemoglobinemia is due to the lack of cytochrome b5 reductase (b5R). b5R is a flavoprotein. There are two types of membrane binding and solubility. Both b5Rs are expression products of the same gene. The gene is located on chromosome 22 and is 31 kb in length. It has been found that there are at least 11 variants of b5R. In addition, five b5R variants have been found, and their electrophoretic behavior is abnormal, but the enzyme activity is normal and belongs to the polymorphism of the enzyme.
The disease is autosomal recessive, divided into 2 types:
Type I: Also known as simple red blood cell type. The patient has a cyanosis since birth, and the blood MetHb content accounts for 8% to 50% of the total amount of Hb.
Type II: Also known as the whole body type. Various cells in the body lack b5R activity, including membrane-bound and soluble, accounting for about 10%. Abnormalities in this type of b5R are associated with the breakdown and elongation of fatty acids, the synthesis of cholesterol, and the metabolism of certain drugs.
