Step I alpha-thalassemia 3 gene deletion

[OrthoRehab33]

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This in regards to Pathoma:
First question: there's 4 alpha genes to make 1 alpha monomer? so HbA= (a2b2) the "a" is an alpha monomer that required 4 alpha genes to be made...is this understanding correct?
Second: 3 gene deletion in utero the fetus is okay because of HbF (a2y2) - you have 1 good allele gene, but when you start replacing the HbF with HbA the child develops Sx but why? HbA (a2B2) forms Beta tetramers, how come the HbF doesnt form gamma tetramers with a 3 gene deletion?

 

[chillaxbro]

You only need one gene for it to be made. But if you have fewer copies, less can be made.

2nd question: yes that is correct. How come the 3 gene deletion you dont form gamma tetramers? I think they do but it doesnt necessarily kill you. In 4 gene deletion, you have no alphas at all so you cant even make HbF which kills you inutero

 

[OrthoRehab33]

You only need one gene for it to be made. But if you have fewer copies, less can be made.

2nd question: yes that is correct. How come the 3 gene deletion you dont form gamma tetramers? I think they do but it doesnt necessarily kill you. In 4 gene deletion, you have no alphas at all so you cant even make HbF which kills you inutero

Thanks! This makes sense