Three generations of a Jamaican family of African extraction are described, in several members of which an abnormal gene is carried. This gene produces high levels of fetal hemoglobin unassociated with the usual stigmata of thalassemia. It is found in all three generations of the family associated with hemoglobin A only and is also found in at least two members of the family interacting with hemoglobin S. In the latter combination little or no disability results.
The mode of inheritance of this abnormal gene is discussed, and reasons are put forward for a possible protective effect of high fetal hemoglobin levels due to inhibition of sickling.
The findings in the cord blood of the youngest child, including an unusually high percentage of sickling, are discussed, together with follow-up studies to the age of 25 weeks.