FREQUENCY AND REGIONAL DISTRIBUTION OF VARIANTS IN HBB AND HBA1/HBA2
GENES IN PATIENTS WITH HEMOGLOBINOPATHIES FROM A SINGLE LARGE
INSTITUTION IN CENTRAL GREECE: INTERPLAY BETWEEN GENOTYPE AND
PHENOTYPE
Michael D. Diamantidis1, Achilles Manafas1, Evangelos Tsangalas1, Georgia Ikonomou2, Christina
Manara1, Ekaterini Karagianni1, Vasiliki Karagianni1, Domna Tsipoliti1, Angeliki-Antonia Tsolaki1 and
Paraskevi Fotiou1
(1) Thalassemia and Sickle Cell Disease Unit, Department of Hematology, General Hospital of Larissa,
Larissa, Greece, (2)Thalassemia Prevention Unit, General Hospital of Larissa, Larissa, Greece
Objectives: To determine the frequency of variants in the HBB and HBA1/HBA2 genes in
patients with hemoglobinopathies followed in a single large center in central Greece
(Thessaly) and to investigate the interplay between genotype and phenotype.
Methods: 132 Greek hemoglobinopathy patients (130 alive, 2 deceased)(49 males, 83
females) including 89 with thalassemia major (TM), 18 sickle cell disease (SCD) (17 sickle
cell/beta-thalassemia and 1 homozygous SCD), 16 thalassemia intermedia (TI), and 9 α-
thalassemia, were evaluated regarding their β- and α- thalassemia genotypes. All TM patients
were regularly transfused, whereas the remaining only with complications (sickle crises,
medical emergencies, pregnancy or giving birth). The vast majority of patients came from the
Larissa prefecture and a few came from other regions of Thessaly (Karditsa, Trikala), or from
other prefectures (Thessaloniki, Phthiotida, Magnisia). It is the largest study conducted in
Thessaly until today. Carriers of a single HBB or HBA1/HBA2 mutations were not evaluated.
DNA analysis was performed in the Laboratory of Medical Genetics, National and Kapodistrian
Athens University, using standard methods such as ARMS-PCR, PAGE, GAP-PCR, RE-PCR and
Sanger sequencing.
Results: The frequency of HBB variant alleles in patients with β-hemoglobinopathies in
Thessaly are shown in the Table. Among the 89 with TM phenotype, 8 patients also had
concomitant alpha thalassemia deletions, either - -Med or -α3.7 and one was compound
heterozygous for cd39 and -101C>T(HBB:c.118C>T;151C>T). Among the 16 patients with
TI, 2 patients had genotype involving δβ deletions with HBB variants without regular
transfusions and 3 patients were double heterozygotes for a triple alpha gene arrangement
and an HBB gene variant. Of these cases, 1 is transfused regularly (IVSI-n1G>A;=and
ααα(anti3.7)), whereas the remaining 2 are transfused very rarely (118C>T;= and
ααα(anti3.7)).
The most common mutation was IVSI-n110G>A(93-21G>A), followed by the cd39C>T(118C>T)
mutation (Table). The very rare mutations (frequency <1%) were: IVSI-n5G>A(92+5G>A) (δβ
Corfu), 78A>G(28A>G), 44bpdel(76_92+27del) and 1480+C>G.
The mutations IVSI-n110G>A(93-21G>A) and the cd39C>T(118C>T) were the most frequently
encountered among the β- gene mutations in sickle cell/beta-thalassemia trait patients.
Interestingly, 1 patient with the genotype 20A>T (βs CD6A>T)/IVSI-n110 (93-
21G>A)/ααα(anti3.7) showed less sickle crises and a more severe degree of anemia.
Six different genotypes contributed to 9 patients with hemoglobinopathy H of our cohort:
8 had mild clinical manifestations without regular transfusions: - -MedI/α2CD127A>T (1
patient), - -MedI/-α3.7(3 patients), αHphlα95+2_95+6delTGAGG/- -MedI (2 patients),