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What is the genetic explanation behind Hgb S?
Glutamic Acid is replaced by Valine in position 6 of the beta chain
What does the Sickledex procedure test for?
- The presence of Hgb S
- Does not indicate amount, or homo/heterozygocity
What is the principle behind the Sickledex test?
- Sodium dithionite or sodium hydrosulfite reduces oxygen tension in the soln
- Tactoids are formed when the O2 environment around the cell is reduced
- This causes the characteristic "sickling" of the cells
- Hgb S Is insoluble after exposure to soln, and the blood will be opaque
What is the procedure (in detail) for the Sickledex test?
- Mix the powdered contents and liquid reagents together
- Place 3mL test soln into three test tubes in holder
- Fill the pipette w/ capillary action to the black line
- Put blood into one test tube, then invert the tube to thoroughly mix
- Put the + control into one tube, and mix
- Put the - control into the final tube, and mix
- Allow to stand
- View through solns for result. If blood is opaque then the patient is Hgb S positive