CO (carbon monoxide). It binds to the same sites on hemoglobin that oxygen would, except with a much greater affinity than oxygen does. Think of hemoglobin as a bus transporting oxygen from the lungs to the peripheral tissues, and think of CO as the guy who takes oxygen's seat so that he can't ride the bus. CO is also the chemical that kills people in house fires from smoke inhalation.
Carbon monoxide
For an infant, normal hemoglobin is 14-22 g/dL
loss of only one amino acid from the normal hemoglobin molecule
Normal levels of hemoglobin for neonates are 17 - 22 g/dl.
Normal levels of hemoglobin for adult females past menopause are 11.7 - 13.8 g/dl.
sickle trait hemoglobin
yes
The normal hemoglobin level ranges from 12-18 grams per deciliter. Above normal hemoglobin levels may result in dehydration, excess production of rbc in bone marrow and other conditions.
Normal Hemoglobin levels in a Male is 13.8 to 17.2 gm/dL but this can vary based on various labs and what they consider to be the normal range.
For adult males the normal hemoglobin values are from 14-18 grams/deciliter. For adult females the normal hemoglobin values are from 12-16 grams/deciliter. I don't know how these values could be expressed as percents.
DNA
40