In α-thalassemias, production of the α-globin chain is affected, while in β-thalassemia, production of the β-globin chain is affected.The β-globin chains are encoded by a single gene on chromosome 11; α-globin chains are encoded by two closely linked genes on chromosome 16. Thus, in a normal person with two copies of each chromosome, two loci encode the β chain, and four loci encode the α chain. Deletion of one of the α loci has a high prevalence in people of African or Asian descent, making them more likely to develop α-thalassemia. β-Thalassemias are not only common in Africans, but also in Greeks and Turks. Alpha-thalassemias
The α-thalassemias involve the genes HBA1 and HBA2, inherited in a Mendelian recessive fashion. Two gene loci and so four alleles exist. Two genetic loci exist for α-globin, thus four alleles are in diploid cells. Two alleles are maternal and two alleles are paternal in origin. The severity of the α-thalassemias is correlated with the number of affected α-globin; alleles: the greater, the more severe will be the manifestations of the disease. Alpha-thalassemias result in decreased alpha-globin production; therefore, fewer alpha-globin chains are produced, resulting in an excess of β chains in adults and excess γ chains in newborns. The excess β chains form unstable tetramers (called hemoglobin H or HbH of 4 beta chains), which have abnormal oxygen dissociation curves. Alpha thalassemias often are found in people from Southeast Asia, the Middle East, China, and in those of African descent.
Its 
  
    
      
        3
      
    
    {\displaystyle 3}
   x 
  
    
      
        3
      
    
    {\displaystyle 3}
   array of squares has a magic constant 
  
    
      
        M
      
    
    {\displaystyle M}
   of 
  
    
      
        15
      
    
    {\displaystyle 15}
  , where the sums of its rows, columns, and diagonals are all equal to fifteen. 5 is also the value of the central cell the only non-trivial order-3 normal magic hexagon that is made of nineteen cells.Polynomial equations of degree 4 and below can be solved with radicals, while quintic equations of degree 5, and higher, cannot generally be so solved. This is the Abel–Ruffini theorem.