The gamma-globin gene rearrangements in newborns from the Republic of Macedonia.

Cord blood samples of 3,232 newborns of different ethnic origins living in the Republic of Macedonia were analyzed by starch gel electrophoresis, polyacrylamide gel electrophoresis and reversed phase high performance liquid chromatography. Hb Bart's was detected in 26 newborns (0.8%) indicating the low incidence of alpha-thalassemia in the Republic of Macedonia. Five different hemoglobin variants (Hb O-Arab, Hb Hamilton, Hb Strumica, Hb F-Macedonia-I, and Hb F-Macedonia-II) were also detected. The levels of the G gamma chains fell into three categories; normal range with G gamma between 50 and 80% (3,143 newborns or 97.2%), low range with G gamma levels of < 50% (35 newborns or 1.1%), and high range with G gamma levels of > 80% (54 newborns or 1.7%). The overall incidence of the A gamma T variant was 20.8%, similar to that found in several Mediterranean populations. DNA analyses showed that the molecular basis of high and low G gamma determinants are heterogeneous in our population. gamma-Gene triplications and the G gamma G gamma arrangements were detected in newborns with high G gamma levels, while gamma gene deletions and A gamma A gamma arrangements were found in newborns with low G gamma levels. All but one of the 135 samples with G gamma between 50 and 80% had the normal G gamma A gamma arrangement on both chromosomes; the only exception was an Albanian newborn (G gamma = 63%) with an-A gamma/G gamma G gamma A gamma arrangement.