Ineffective erythropoiesis (red blood cell production) can also lead to compensatory bone marrow expansion which can then lead to bony changes/deformities, bone pain and craniofacial abnormalities. Extramedullary organs such as the liver and spleen that can also undergo erythropoiesis become activated leading to hepatosplenomegaly (enlargement of the liver and spleen). Other tissues in the body can also become sites of erythropoiesis, leading to extramedullary hematopoietic pseudotumors which may cause compressive symptoms if they occur in the thoracic cavity or spinal canal. Cause
Mutations
Two major groups of mutations can be distinguished:

Nondeletion forms: These defects, in general, involve a single base substitution or small insertions near or upstream of the β globin gene. Most often, mutations occur in the promoter regions preceding the beta-globin genes. Less often, abnormal splice variants are believed to contribute to the disease. Deletion forms: Deletions of different sizes involving the β globin gene produce different syndromes such as (βo) or hereditary persistence of fetal hemoglobin syndromes.Mutations are characterized as (βo) if they prevent any formation of β globin chains, mutations are characterized as (β+) if they allow some β globin chain formation to occur. mRNA assembly
Beta thalassemia is a hereditary disease affecting hemoglobin. As with about half of all hereditary diseases, an inherited mutation damages the assembly of the messenger-type RNA (mRNA) that is transcribed from a chromosome.
Adiposogenital dystrophy is a condition that may be caused by tertiary hypogonadism originating from decreased levels in GnRH. Low levels of GnRH has been associated with defects of the feeding centers of the hypothalamus, leading to an increased consumption of food and thus caloric intake. Presentation
It is characterized by:
Obesity
Growth delays and delayed sexual development, atrophy or hypoplasia of the gonads, and altered secondary sex characteristics,
Headaches
Problems with vision
polyuria, polydipsia.It is usually associated with tumors of the hypothalamus, causing increased appetite and depressed secretion of gonadotropin. It seems to affect males mostly.Many overweight children may appear to have the disorder because of the concurrence of obesity and retarded sexual development; these children have no endocrine disturbances, however, and they mature normally after delayed puberty. Diagnosis
Laboratory analysis of the urine from children with Froehlich syndrome typically reveals low levels of pituitary hormones, and that finding may suggest the presence of a lesion on the pituitary. Additional tests are needed before a definite diagnosis of Froehlich syndrome may be made. Treatment
Pituitary extracts may be administered to replace the missing hormones (hormonal replacement therapy) in patients with Froehlich syndrome. Tumors of the hypothalamus should be surgically removed if possible. Appetite may be very difficult to manage, although weight control depends on this. References


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