Low O2 levels are not the only issue with sickle cell trait. You can develop complications just from the increased atmospheric pressure experienced during diving. Here is an excerpt from the CDC:
"What Health Complications Are Associated
With Sickle Cell Trait?
Most people with SCT do not have any symptoms of SCD, although
— in rare cases — people with SCT might experience complications
of SCD, such as “pain crises” and, in extreme circumstances, sudden
death. More research is needed to find out why some people with
SCT have complications and others do not.
In their extreme form and in rare cases, the following conditions
could be harmful for people with SCT:
•• Increased pressure in the atmosphere (e.g., while scuba diving).
•• Low oxygen levels in the air (e.g., when mountain climbing,
exercising extremely hard in military boot camp, or training for
an athletic competition).
•• Dehydration (e.g., too little water in the body).
•• High altitudes (e.g., flying, mountain climbing, or visiting a city at
a high altitude)."
Given the above, if I was your instructor I would want a DAN affiliated physician to sign off on you participating in diving activities before allowing you to participate in any in-water training.
This is an issue that you should disclose to any of the people you are buddied up with as well, as you are their backup just as much as they are your backup...they should know that you are at risk of complications during the dive.
I would recommend you find another activity to invest yourself in. Your condition puts you and those you dive with at risk. The underwater world is a beautiful place but it is also an unforgiving domain...the fact that you may be aware of the risk your condition presents does not mean it should be imposed on anyone else.
-Z
"What Health Complications Are Associated
With Sickle Cell Trait?
Most people with SCT do not have any symptoms of SCD, although
— in rare cases — people with SCT might experience complications
of SCD, such as “pain crises” and, in extreme circumstances, sudden
death. More research is needed to find out why some people with
SCT have complications and others do not.
In their extreme form and in rare cases, the following conditions
could be harmful for people with SCT:
•• Increased pressure in the atmosphere (e.g., while scuba diving).
•• Low oxygen levels in the air (e.g., when mountain climbing,
exercising extremely hard in military boot camp, or training for
an athletic competition).
•• Dehydration (e.g., too little water in the body).
•• High altitudes (e.g., flying, mountain climbing, or visiting a city at
a high altitude)."
Given the above, if I was your instructor I would want a DAN affiliated physician to sign off on you participating in diving activities before allowing you to participate in any in-water training.
This is an issue that you should disclose to any of the people you are buddied up with as well, as you are their backup just as much as they are your backup...they should know that you are at risk of complications during the dive.
I would recommend you find another activity to invest yourself in. Your condition puts you and those you dive with at risk. The underwater world is a beautiful place but it is also an unforgiving domain...the fact that you may be aware of the risk your condition presents does not mean it should be imposed on anyone else.
-Z
Unfortunately I don't know what my HbS percentage is yet.
), even looked into Navy research on the subject (SCT is not a disqualifier for naval special warfare, including the Seals), and even purchased several research papers from online medical databases going as far back as the 80's. 
