Hb F-Macedonia-II [G gamma 104(G6)Lys-->Asn]: a new gamma chain variant

Thalassemias and Other Hemoglobinopathies in the Republic of Macedonia

This paper summarizes the results on the epidemiology and molecular basis of thalassemias and other hemoglobinopathies in the Republic of Macedonia. Over the past 40 years, population surveys of more than 22,000 participants (school children and workers) from all over the country, have shown that the average incidence of beta-thalassemia (thal) trait is 2.6%, ranging from less than 1% in the northeast to 10% in the south. The frequency of deltabeta-thal is 0.2%, while the frequency of the Swiss type of hereditary persistence of fetal hemoglobin (HPFH) is 0.3%. Screening of 9,619 newborns has shown that the frequency of alpha-thal trait is 1.5%, of which alpha-thal-2 is 1.45% and alpha-thal-1 is 0.05%. The molecular basis of the different forms of beta-thal and other hemoglobinopathies has been completely defined. Among the Macedonians, over 450 beta-thal chromosomes have been studied. Fifteen different beta-thal mutations have been detected, four of which [IVS-I-110 (G-->A), IVS-I-6 (T-->C), IVS-I-1 (G-->A), codon 39 (C-->T)] account for 85% of all beta-thal chromosomes. Among the Albanians, 48 beta-thal chromosomes have been studied. Eight different mutations have been detected, four of which [codon 39, -30 (T-->A), IVS-I-110, IVS-I-1] account for 85% of all beta-thal chromosomes. Four new mutations [-101 (C-->A), -87 (C-->G), -30, polyadenylation signal (poly A) (AATAAA-->AATGAA)] have been characterized. Molecular analyses of DNA from over 20 unrelated cases with deltabeta-thal have shown that this condition is caused by a 13 kb deletion (Sicilian type); in two families a deletion of 18 to 23 kb (Macedonian type of deltabeta-thal) was discovered. Molecular analyses of alpha-thal in the Republic of Macedonia have shown the following types of molecular defects: 20.5 kb deletion, 17.5 kb deletion, 3.7 kb deletion, poly A mutation (AATAAA-->AATGAA), and Hb Icaria [alpha142, Term-->Lys, TAA-->AAA (alpha2)]. The incidence of abnormal hemoglobins (Hbs) in the Republic of Macedonia is 0.4%. Three different alpha chain variants among 10 families, seven different beta chain variants among 33 families, two gamma chain variants in two newborns, one variant with an extended alpha chain, and Hb Lepore among 105 families, have been observed. Structural analysis of numerous cases with Hb Lepore showed that the variant was of the Washington-Boston type.

Thalassemias and Other Hemoglobinopathies in Former Yugoslavia

This review summarizes our results on the epidemiology and molecular basis of thalassemias and other hemoglobinopathies in the republics and provinces of the Former Yugoslavia. Over the past 40 years, surveys of more than 37,000 school children and more than 1,600 adults, from all over Former Yugoslavia, except Slovenia, have shown an average incidence of β-thalassemia (β-thal) trait of 1.2%, ranging from 2.9% in the south (Macedonia) to 0.8% in the northwest (Croatia). The frequency of δβ-thal was 0.2%, while that of Swiss type hereditary persistence of fetal hemoglobin (HPFH) was 0.4%. Screening of 12,680 newborns has shown that the frequency of α-thal trait was 1.5%. The molecular basis of the thalassemias in the populations of Former Yugoslavia has been completely defined. More than 700 β-thal chromosomes have been studied and their molecular defect was determined. In the Macedonian population, 16 different β-thal mutations were detected, four of which (IVS-I-110, G→A; IVS-I-6, T>C; IVS-I-1, G>A and codon 39, C>T) accounted for 85% of all β-thal chromosomes. In the Croatian population, 18 different β-thal alleles were detected. Four new mutations [nucleotide (nt) -87, C>A; IVS-II-850, G>C; initiation codon mutation T>C; polyadenylation signal (poly A), AATAAA>AATGAA)] and one new deletion (1605 bp), were characterized. Molecular analyses of DNA from over 50 unrelated cases with δβ-thal have shown that this condition was mainly caused by a 13 kb deletion (Sicilian type); in one family, a deletion of >18 to 23 kb (Macedonian-Turkish type), and in another, a deletion of 148 kb (Yugoslavian type of εγδβ-thal) of the β-globin gene complex, were discovered. Molecular analyses of α-thal from Former Yugoslavia revealed the following defects: the -20.5, -17.5 and -3.7 kb deletions, a 5 nt deletion, and Hb Icaria [α142, Term→Lys (TAA>TCA in α2)]. The incidence of abnormal hemoglobins (Hbs) in Former Yugoslavia was 0.3%. Five different α chain variants in 16 families, 16 different β chain variants in 61 families, one δ chain variant in one family, two types of Hb Lepore in 122 families and two γ chain variants, have been characterized.

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.