Summary Pyruvate kinase (PK) deficiency is an iron‐loading anaemia characterized by chronic haemolysis, ineffective erythropoiesis and a requirement for blood transfusion in most cases. We studied 11 patients from 10 unrelated families and found nine different disease‐causing PKLR mutations. Two of these mutations ‐ the point mutation c.878A>T (p.Asp293Val) and the frameshift deletion c.1553delG (p.(Arg518Leufs*12)) ‐ have not been previously described in the literature. This frameshift deletion was associated with an unusually severe phenotype involving neonatal hyperferritinaemia that is not typical of PK deficiency. No disease‐causing mutations in genes associated with haemochromatosis could be found. Inappropriately low levels of hepcidin with respect to iron loading were detected in all PK‐deficient patients with increased ferritin, confirming the predominant effect of accelerated erythropoiesis on hepcidin production. Although the levels of a putative hepcidin suppressor, growth differentiation factor‐15, were increased in PK‐deficient patients, no negative correlation with hepcidin was found. This result indicates the existence of another as‐yet unidentified erythroid regulator of hepcidin synthesis in PK deficiency.

β-Thalassemia (β-thal) is considered rare in Central Europe. As in other malaria-free regions, the presence of β-thal in Central Europe reflects historical and recent immigration, and demographic changes that have influenced the genetic variability of the current populations living in this area. This study assesses the frequency and spectrum of mutations on the β-globin gene in Czech and Slovak subjects with clinical symptoms of thalassemia. The results of the initial part of this research were published more than two decades ago; the aim of this study was to update these original reports. During the period from 2002 to 2015, 400 cases from Czech and Slovak hematological centers were analyzed. Twenty-nine β-thal mutations, identified in 356 heterozygotes from 218 unrelated families, involve five unique mutations including a recently described insertion of a transposable L1 element into the β-globin gene. One mutation described here is reported for the first time. Most of the mutations were of Mediterranean origin and accounted for 82.0% of cases. All but one case studied were heterozygous carriers, manifesting β-thal minor, with rare exceptions represented by the rare (β(0)) codons 46/47 (+G) (HBB: c.142_142dupG) mutation associated with an α-globin gene quadruplication and by dominantly inherited β-thal with a more severe phenotype. One double heterozygous β-thal patient was a recent immigrant from Moldavia. The list of δβ-thal alleles (26 carriers, 16 families) contains Hb Lepore and two types of δβ(0)-thal deletions. In the past, genetic drift and migration as well as recent immigrations were responsible for the introduction of Mediterranean alleles, while several mutations described in single families were of local origin.

5307 Background: Thalassemias are rare disorders in Middle Europe. However, as a result of historical and recent migration, thalassemias became common cause of congenital anemia in the Czech and Slovak populations. Abnormal hemoglobin variants and red-cell enzymopathies are rare cause of congenital anemia in this region. The aim of this work was to update the original reports of this research published almost two decades ago (Indrak et al., Hum Genet 1992; 88:399–404, Xu et al., Blood 1995; 85:257–63, Lenzner et al., Blood 1997; 89:1793–9). We assessed the frequency and spectrum of β-globin gene mutations in the patients with clinical symptoms of β-thalassemia or δ,β-thalassemia, the α-globin gene status in the patients with clinical symptoms of α-thalassemia, and we characterized red cell enzymopathies on molecular level in the Czech and Slovak populations. Patients and methods: Nearly 390 cases with clinical symptoms of thalassemia or hereditary nonspherocytic hemolytic anemia from several centers of Czech and Slovak Republic were analyzed. Hematological parameters, hemoglobin electrophoresis and enzyme activities were measured by standard procedures. Genomic DNA was used for PCR-sequencing analysis. Results: We identified 22 β-thalassemia mutations in more than 260 heterozygotes; most of the mutations were of Mediterranean origin. The newly discovered insertion of transposable element L1 into the HBB gene represents a novel etiology of β-thalassemia due to a silencing effect of repressive chromatin associated with retrotransposon insertion. The list of abnormal hemoglobins now contains 14 β-globin variants, involving Heinz body hemolytic anemia variant Hb Hana (β63(E7) His-Asn), phenotype of which was worsened by concomitant partial glutathione reductase deficiency (Mojzikova et al., Blood Cells Mol Dis 2010; 45:219–22). Several G6PD and PK variants were described in the Czech and Slovak populations; the G6PD variants include G6PD Olomouc, G6PD Varnsdorf and G6PD Praha. Recently, we identified a new frameshift mutation c. 1553delG (p. Arg518fs) at the homozygous state in exon 11 of the PKLR gene of the pediatric patient who suffered from transfusion dependent hemolytic anemia with Hb=9.4 g/dL, Ret=4.5%. His red cells PK activity was 4.52 IU/gHb (normal range 13–17 IU/gHb). The mutation occurs in C domain of PK-R subunit containing the binding site for fructose-1,6-bisphosphate. The patient's extremely elevated level of growth differentiation factor 15 (GDF15, 3577 pg/mL, healthy controls 231–345 pg/mL) could explain hereditary hemochromatosis and signs of iron overload in this patient. Conclusions: In the Czech and Slovak populations, hemoglobinopathies and red-cell enzymopathies appear to be an uncommon disorder, which, however, must be considered as the prevailing cause of congenital anemia. Most of the thalassemia patients were heterozygous, manifesting thalassemia minor. Most of the hemoglobin variants were described in single families, some of them originated locally. Among hemolytic anemias due to red-cell enzymopathies is the most frequent PK deficiency. This work was supported by grants NT11208, NS10281 (Ministry of Health Czech Republic), MSM6198959205 (Ministry of Education, Youth and Sports) and student projects LF_2011_006 and LF_2011_011 of the Palacky University. Disclosures: No relevant conflicts of interest to declare.