DNA contains both the instructions (genes) for stringing amino acids together into proteins, as well as stretches of DNA that play important roles in regulating produced protein levels.In thalassemia, an additional, contiguous length or a discontinuous fragment of non-coding instructions is included in the mRNA. This happens because the mutation obliterates the boundary between the intronic and exonic portions of the DNA template. Because all the coding sections may still be present, normal hemoglobin may be produced and the added genetic material, if it produces pathology, instead disrupts regulatory functions enough to produce anemia. Hemoblogins normal alpha and beta subunits each have an iron-containing central portion (heme) that allows the protein chain of a subunit to fold around it. Normal adult hemoglobin contains 2 alpha and 2 beta subunits. Thalassemias typically affect only the mRNAs for production of the beta chains (hence the name). Since the mutation may be a change in only a single base (single-nucleotide polymorphism), on-going efforts seek gene therapies to make that single correction. Risk factors
Family history and ancestry are factors that increase the risk of beta thalassemia. Depending on family history, if a persons parents or grandparents had beta thalassemia major or intermedia, there is a 75% (3 out of 4) probability (see inheritance chart at top of page) of the mutated gene being inherited by an offspring. Even if a child does not have beta thalassemia major or intermedia, they can still be a carrier, possibly resulting in future generations of their offspring having beta thalassemia.Another risk factor is ancestry.
A urachal fistula is a congenital disorder caused by the persistence of the allantois (later, urachus), the structure that connects an embryos bladder to the yolk sac. Normally, the urachus closes off to become the median umbilical ligament; however, if it remains open, urine can drain from the bladder to an opening by the umbilicus.This condition is a rare defect, mostly found in children, and is also known as an open or patent urachus. == References ==