Mostly found in Northern India and in the Uyghur population (China), sometimes called Hb Los Angeles, where it has been first described. Hemoglobin abnormality due to the replacement of glutamic acid with glutamine at position 121 in the  β chain of hemoglobin.

-  heterozygous form:        25 to 40 % hemoglobin D at electrophoresis;  no clinical signs. Blood smear: target red blood cells. The association with the HbS trait leads to severe sickle cell syndrome (see drepanocytosis)

-  homozygous form:        > 95 % hemoglobin D at electrophoresis; splenomegaly, sometimes chronic hemolytic anemia with reticulocytosis, target red blood cells.

Anesthetic implications: 

check hemoglobin levels and for a possible association with the sickle cell trait

References : 

Updated: October 2021