Aplasia (/əˈpleɪʒə/ ⓘ; from Greek a, "not", "no" + plasis, "formation") is a birth defect where an organ or tissue is wholly or largely absent.
[8] Men often learn they have Sertoli cell-only syndrome between the ages of 20 and 40 when they are checked for infertility and found to produce no sperm.
[9] Most cases of SCO syndrome are idiopathic, however, causes may include deletions of genetic material on Y-chromosome regions, particularly the azoospermia factor area.
[9] Pulmonary aplasia is a rare congenital pathology characterized by the unilateral or bilateral absence of lung tissue.
Thymic aplasia is a rare primary immunodeficiency with autosomal or X-linked recessive inheritance, characterized by thymus atrophy in the absence of other congenital abnormalities, profound T-cell deficiency, and normal or increased serum immunoglobulin levels.
Clinically, the condition is characterized by a lack of light perception, an afferent pupillary defect, and a fundus appearance of an absent optic nerve head and retinal vessels, as well as other ocular and nonocular abnormalities.
Although the anemia is usually normocytic, mild macrocytosis can be seen in conjunction with stress erythropoiesis and raised fetal hemoglobin levels.
Aplastic anemia patients present with symptoms related to a decrease in hematopoietic cell production in the bone marrow.
The following are examples of specific manifestations:[12] The majority of cases of aplastic anemia are idiopathic, and seeking a possible cause is frequently unproductive.