Clinical manifestations of congenital hematopoietic disorders

Congenital hematopoietic dysfunction is also relatively common in clinical practice. Most of the patients are infants and young children. Some children develop the disease within two weeks to two years after birth. Generally, many children can be diagnosed within one year old. Congenital hematopoietic dysfunction has many clinical manifestations, which often cause anemia and bleeding, and are particularly harmful to children.

Clinical manifestations of congenital hematopoietic dysfunction (I) Congenital pure diamond-blackfan anemia: 90% of cases develop between birth and 1 year old, rarely after 2 years old, the inheritance pattern is still unclear, and it is familial. The children have slow growth and development, and a few have mild congenital malformations, such as thumb deformities. Unlike Fanconi anemia, they are rarely associated with malignant diseases. The patient's erythroid progenitor cells are not only deficient in number, but also have qualitative abnormalities. Increased HbF, persistent presence of fetal membrane antigen i, and increased activity of purine salvage pathway enzymes indicate defects in nucleic acid synthesis. Patients' lymphocytes can inhibit the growth of normal erythroid progenitor cells in vitro. 20% of cases can achieve spontaneous remission, 60% of patients respond to adrenal cortex hormones, and those who do not respond can also undergo bone marrow transplantation. (ii) Acute acquired pure red blood cell aplasia: Viral infection during the course of chronic hemolytic anemia, especially human parvovirus (parvovirus) B19 infection, can selectively inhibit erythroid progenitor cells, resulting in acute pure red blood cell aplasia, also known as aplastic crisis of hemolytic anemia. In some cases, hematopoiesis temporarily stops after viral infection, leading to pancytopenia and the appearance of giant red blood cells in the bone marrow, also known as acute hematopoietic stagnation. Acute pure red cell aplastic anemia can also occur in children aged 1 to 4 years old, and heal itself after a few weeks without any infectious factors. It is called transient erythroblastopenia in children. Acute pure red aplastic anemia is also seen in viral hepatitis and certain drug-induced diseases, such as phenytoin, azathioprine, chloramphenicol, isoniazid and procainamide. Most cases will recover completely after stopping the drug.

(III) Chronic acquired pure red cell aplastic anemia is mainly seen in adults. 50% of patients have thymoma, and only 5% of thymoma patients have pure red cell aplasia; most of these thymomas are benign, 70% are spindle cell type, and a few are malignant; they are more common in women (female:male ratio is 3-4.5:1). A few cases may also be secondary to certain autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis, and certain tumors such as chronic lymphocytic leukemia, chronic myeloid leukemia, lymphoma, immunoblastic lymphadenopathy, biliary adenocarcinoma, thyroid cancer, bronchial lung cancer and breast cancer. Those with unknown causes are called primary acquired pure red blood cell aplasia, which is caused by multiple immune mechanisms leading to the inhibition of erythropoiesis. Anti-erythroblast antibodies, anti-erythropoietin antibodies or inhibitory T lymphocytes exist in the patient's serum. Patients often have multiple immunological abnormalities such as increased or decreased immunoglobulins, monoclonal immunoglobulins, and multiple positive serum antibodies, such as cold agglutinins, cold hemolysins, heterophilic antibodies, antinuclear antibodies, etc. Anti-human globulin test, etc. are positive. Some patients may have decreased function of multiple endocrine glands. Pure erythropoietic anemia without thymoma is more common in males (male:female ratio is 2:1).

The cause of the disease is congenital aplastic anemia, which is occasionally seen in siblings, suggesting that congenital aplastic anemia is a hereditary disease. Less than 10% of patients have a family history, and the majority of the rest are sporadic. One third of patients have autosomal dominant inheritance, and the rest have recessive inheritance. Linkage analysis revealed that there are at least three genetic loci for DBA, two of which have been identified, namely 19q13.2 and 8p23.3-p22. The related pathogenic gene has been cloned in the 19q13.2 region, which is the ribosomal protein S19 (RPS19) gene. Sequence analysis found that approximately 25% of DBA patients had RPS19 mutations.

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