While at Cambridge in 1956 Vernon Ingram (late of MIT)
discovered that it was a single amino acid substitution
in the beta globin protein that was responsible for the
molecular abnormality leading to Sickle Cell Anemia.



Beta Sickle sequence
 
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                  sickle trait
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    A blood and bone marrow transplant is currently the only cure for some patients who
    have SCD. Some medicines can alleviate pain: Hydroxyurea, help prevent sickle shape,
    transfusions supply normal Hb, and antibiotics to reduce infections.
 
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 Sickle Cell disease
occurs when the DNA sequence for glutamic acid is converted to valine.
 This results from a change in the nucleotide T to A.
 This change eliminates a site recognized by the restriction enzyme DdeI, that comes
 from the bacteria Desulfovibrio desulfuricans

 Restriction enzyme: DdeI (cuts DNA at recognition sequence: 5'-C^TNAG-3')

 Pattern result: normal cell  =  3 fragments  (1 large, a 201bp piece, and a 175bp piece)
                          sickle cell  =  2 fragments  (1 large piece and a 376bp piece)

   fig 20.9
* Thus the number of RFLP piece can indicate presence of defective alleles.


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 







 
 
 
 
 

 
 DdeI is a restriction enzyme isolated from Desulfovibrio desulfuricans, a Gram-negative sulfate
 reducing soil bacteria) that can digest 1ug DNA in 1 hr @ 37C at cut site 5'C|TNAG3'
                                                                                                                     3'GANT|C5' 

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