On genetic diagnosis,they were all Southeast Asia(SEA) type of α thalassemia 1 and β thalassemia (-- SEA /αα, β T/β A)dual heterozygotes. Out of them, 3 cases were α thalassemia 1 and β 41 42(-TCTT), 2 were α thalassemia 1 and β-28(A→T) and 1was α thalassemia 1 and β IVS Ⅱ 654(C→T) double heterozygotes.
This study was using cord blood electrophoresis to screen alpha tha-lassemia in 204 newborns who were born in our hospital obstetrics from April to Dec. 1994. We identified 19 carriers of standard gene alpha thalassemia(11%) and 5 carriers of arrested gene (7%).
Among this group 7 patients suffered from α-thalassemia hemoglobin H disease and one patient from homozygous β-thalassemia.
Two other patients had decreased α/β ratios in the peripheral blood, probably because of the presence of an α-thalassemia gene.
The study depended on (a) most of the Hb H disease in Taiwan having anα-thalassemia-1 of the Southeast Asia type (-SEA) in one allele and (b) the differences of X box ofα-globin gene cluster in the other allele.
Rapid detection of -α4.2 deletion of α-thalassemia-2 by polymerase chain reaction
We sequenced part of the X boxes ofα-thalassemia-1 of Southeast Asia type (- -SEA) with-α4.2,-α3.7,-αG-Taichung, andαCSα.
The elevated expression of αJ chains in heterozygotes with 38% Hb J may be due to an α thalassemia gene trans to the α>amp;gt;J locus.
Therefore, the possibility of coexistence of an α thalassemia trait with a β thalassemia trait in the mother of the proposita and with Hb G San José heterozygosity in the two sisters who had lowered levels of abnormal Hb is discussed.
The obtained DNA pattern in all cases indicated loss of α-globin genes resulting in-α/αα,--/αα, and--/-α genotypes in αthalassemia-2, α-thalassemia-1, and Hb H individuals respectively.
High frequency of triplicated α-globin loci and absence or low frequency of α thalassemia in Polynesian Samoans
We have confirmed the strict relationship between Hb S levels and the number of α globin genes in double heterozygotes for the S gene and α thalassemia.
Alpha thalassemia retardation associated with chromosome16 (ATR-16 syndrome) is defined as a contiguous gene syndrome resulting from haploinsufficiency of the α-globin gene cluster and genes involved in mental retardation (MR).
As there were few cases of iron deficiency amongst these children, the authors concluded that alpha thalassemia was a major contributor to the anemia.
Karyotype analysis, alpha thalassemia screening, congenital infections should be done in all cases.