A novel deletion/insertion caused by a replication error in the β-globin gene locus control region

Deletions in the β-globin locus control region (β-LCR) lead to (εγδβ)(0)-thalassemia [(εγδβ)(0)-thal]. In patients suffering from these rare deletions, a normal hemoglobin (Hb), phenotype is found, contrasting with a hematological thalassemic phenotype. Multiplex-ligation probe amplification (MLPA) is an efficient tool to detect β-LCR deletions combined with long-range polymerase chain reaction (PCR) and DNA sequencing to pinpoint deletion breakpoints. We present here a novel 11,155 bp β-LCR deletion found in a French Caucasian patient which removes DNase I hypersensitive site 2 (HS2) to HS4 of the β-LCR. Interestingly, a 197 bp insertion of two inverted sequences issued from the HS2-HS3 inter-region is present and suggests a complex rearrangement during replication. Carriers of this type of thalassemia can be misdiagnosed as an α-thal trait. Consequently, a complete α- and β-globin gene cluster analysis is required to prevent a potentially damaging misdiagnosis in genetic counselling.     

A Family with the 619 bp Deletion on the β-globin Gene Found in Kerman Province,Iran

In the present study, we report the first case of a 619 bp deletion on the β-globin gene, found in a family from Kerman Province, Iran. This mutation is frequent in Pakistan, but it has not been previously reported in any part of Iran. This study revealed that all family members have this β⁰-thalassemia (β⁰-thal) mutation.     

Release of retinal growth hormone in the chick embryo: Local regulation?

The neural retina is an extrapituitary site of growth hormone (GH) production and an autocrine or paracrine site of retinal GH action. Retinal GH is released from retinal tissue and may be secreted into the vitreous. Ontogenetic changes in the abundance of retinal GH during embryogenesis indicate that the amount of GH released may be regulated. The presence of pituitary GH secretagogues (GH-releasing hormone, GHRH; thyrotropin-releasing hormone, TRH; and ghrelin) and pituitary GH inhibitors (somatostatin, SRIF and insulin-like growth factor, IGF-1) within the neural retina may indicate the involvement of these factors in retinal GH release. This possibility is supported by the finding that GHRH is colocalized with GH in chick retinal ganglion cells (RGCs) and in immortalized cells (QNRD) derived from quail neuroretinal cells and by the induction of GH mRNA in incubated QNRD cells. In summary, these results provide evidence for the autocrine or paracrine regulation of retinal GH release in the ganglion cells of the embryonic chick retina.     

An embryonic stage-specific enhancer within the murine β-globin locus mediates domain-wide histone hyperacetylation

In mammalian nuclei, a select number of tissue-specific gene loci exhibit broadly distributed patterns of histone modifications, such as histone hyperacetylation, that are normally associated with active gene promoters. Previously, we characterized such hyperacetylated domains within mammalian β-globin gene loci, and determined that within the murine locus, neither the β-globin locus control region nor the gene promoters were required for domain formation. Here, we identify a developmentally specific erythroid enhancer, hypersensitive site-embryonic 1 (HS-E1), located within the embryonic β-globin domain in mouse, which is homologous to a region located downstream of the human embryonic ε-globin gene. This sequence exhibits nuclease hypersensitivity in primitive erythroid cells and acts as an enhancer in gain-of-function assays. Deletion of HS-E1 from the endogenous murine β-globin locus results in significant decrease in the expression of the embryonic β-globin genes and loss of the domain-wide pattern of histone hyperacetylation. The data suggest that HS-E1 is an enhancer that is uniquely required for β-like globin expression in primitive erythroid cells, and that it defines a novel class of enhancer that works in part by domain-wide modulation of chromatin structure.     

Molecular analysis of the β-globin gene cluster haplotypes in a Sudanese population with sickle cell anaemia

Introduction: Sudan has a multiethnic population with a high frequency of Hb S, but little is known about the β^S haplotypes in this population. Methods: Blood samples from Sudanese Hb SS individuals were taken at two locations. Family history, age, ethnicity and clinical symptoms were recorded for each subject. Hb S was investigated using cellulose acetate electrophoresis (CAE) and cation exchange–high performance liquid chromatography. Dried blood samples from 93 individuals were used for β^S haplotype identification based on restriction fragment length polymorphism analysis for seven restriction sites. Results: Haplotypes could be assigned unequivocally to 143 chromosomes. Four of the five typical β^S‐globin haplotypes were identified. The most frequent was the Cameroon (35.0%), followed by the Benin (29.4%), the Senegal (18.2%) and the Bantu (2.8%). The Indian‐Arab haplotype was not observed. Three atypical haplotypes were identified in 17 patients, occurring at a combined frequency of 14.6%. One of these, found at the high frequency of 11.8%, possibly represented a new Sudan haplotype. Conclusion: β^S Haplotyes were demonstrated successfully from dried blood samples. A new haplotype is apparent in Sudan, in addition to the four African haplotypes.     

Geographical distribution of β-globin gene mutations in Syria

ABSTRACT

Objectives: β-Thalassemia disease is caused by mutations in the β-globin gene. This is considered as one of the common genetic disorders in Syria. The aim of this study was to identify the geographical distribution of the β-thalassemia mutations in Syria.

Methods: β-Globin gene mutations were characterized in 636 affected patients and 94 unrelated carriers using the amplification refractory mutations system-polymerase chain reaction technique and DNA sequencing.

Results: The study has revealed the presence of 38 β-globin gene mutations responsible for β-thalassemia in Syria. Important differences in regional distribution were observed. IVS-I.110 [G?>?A] (22.2%), IVS-I.1 [G?>?A] (17.8%), Cd 39 [C?>?T] (8.2%), IVS-II.1 [G?>?A] (7.6%), IVS-I.6 [T?>?C] (7.1%), Cd 8 [?AA] (6%), Cd 5 [?CT] (5.6%) and IVS-I.5 [G?>?C] (4.1%) were the eight predominant mutations found in our study. The coastal region had higher relative frequencies (37.9 and 22%) than other regions. A clear drift in the distribution of the third common Cd 39 [C?>?T] mutation in the northeast region (34.8%) to the northwest region (2.5%) was noted, while the IVS-I.5 [G?>?C] mutation has the highest prevalence in north regions. The IVS-I.6 [T?>?C] mutation had a distinct frequency in the middle region. Ten mutations ?86 [C?>?G], ?31 [A?>?G], ?29 [A?>?G], 5′UTR; +22 [G?>?A], CAP?+?1 [A?>?C], Codon 5/6 [?TG], IVS-I (?3) or codon 29 [C?>?T], IVS-I.2 [T?>?A], IVS-I.128 [T?>?G] and IVS-II.705 [T?>?G] were found in Syria for the first time.

Conclusions: These data will significantly facilitate the population screening, genetic counseling and prenatal diagnosis in Syrian population.     

A unique combination of inhibitory and partially activating mutations in β3 of a patient with variant-type Glanzmann thrombasthenia

Thrombocytopenia is classically defined as a platelet count of less than 150?000/µl. Counts from 100?000 to 150?000/µl are considered mildly depressed, 50?000 to 100?000/µl moderately depressed, and less than 50?000/µl severely depressed. Thrombocytopenia occurs in about 10% of pregnant women. Gestational thrombocytopenia (GT) is a diagnosis of exclusion and considered the most prevalent cause of thrombocytopenia in pregnancy. GT accounts for almost 75% of cases of thrombocytopenia in pregnancy. The cause of GT is unclear, although existing studies denote the possibility of accelerated platelet consumption and the increased plasma volume during pregnancy. The presence of antiplatelet antibodies is not specific to GT. The degree of thrombocytopenia in GT is usually mild to moderate, usually remaining greater than 70?000/µl. Patients are asymptomatic with no evidence of bleeding and rarely preconception history of thrombocytopenia. The platelet count returns to normal within 2–12 weeks post partum. We wish to report a unique case of GT presenting as blurred vision due to retinal hemorrhages.     

Compounds of the anthracycline family of antibiotics elevate human γ-globin expression both in erythroid cultures and in a transgenic mouse model

We examined the effect of the anthracyclines aclarubicin, bleomycin, daunorubicin, doxorubicin and idarubicin on human γ- and β-globin promoter activity in an in vitro luciferase assay, ex vivo in erythroid cultures and in vivo in transgenic mice carrying the human γ-globin gene. Effects in erythroid liquid cultures derived from healthy donors were assayed by evaluating HbF production with high performance liquid chromatography and by measuring mRNA levels of the globin genes and the proportion of erythroblasts containing HbF. Compounds testing positive in the in vitro and ex vivo assays were applied to erythroid cultures derived from thalassaemic patients. Doxorubicin, idarubicin and daunorubicin increased HbF production in cultures of both, healthy and thalassaemic donors. Daunorubicin induced HbF in thalassaemic cells ex vivo with the highest statistical significance and, importantly and in contrast to the clinical HbF inducer hydroxyurea, showed specific induction of γ-globin without associated induction of α-globin. Daunorubicin was screened in transgenic mice carrying the human ^Aγ-globin gene, and it resulted in increased ^Aγ-globin mRNA levels. Our results indicate that anthracyclines are a promising group of compounds with the potential to provide lead substances for the synthesis of new agents with clinical applications as γ-globin gene inducers. In parallel, future studies of the epigenetic effects of the five anthracyclines on the β-globin locus will generate possible mechanistic leads on the regulation of the globin genes.     

A deletion of 11 bp (CD 131–134) in exon 3 of the β-globin gene produces the phenotype of inclusion body β-thalassemia

Dominant inherited -thalassemias describe those -thalassemia variants that result in a thalassemia intermediate phenotype in individuals who have inherited only a single copy of the abnormal gene. This form of thalassemia is characterized by moderately severe anemia with jaundice and splenomegaly; it is also characterized by the presence of inclusion bodies in the red blood cell precursors and has, therefore, previously been referred to as inclusion body -thalassemia. We describe a case of inclusion body -thalassemia in a 51-year-old Spanish male caused by a deletion of 11 bp (CD 131–134) in exon 3 of the -globin gene. The deletion of 11 bp in exon 3 of the -globin chain is predicted to produce an anomalous chain of 134 amino acids instead of the normal 146 with an extremely altered amino acid sequence from residues 131–134. Although this shortened variant would lead to a missing H helix, which is involved in ₁₁ contact and ₁₂ subunit interactions, the variant chain can still be bound to the heme group and acquire a secondary structure that is not suitable for the formation of stable dimers or tetramers and also less susceptible to proteolytic degradation. This is the first report of such a -thalassemia mutation.     

The genetic heterogeneity of β-globin gene defects in Sicily reflects the historic population migrations of the island

The aim of this study is to update the incidence and the distribution of the globin gene defects causing β-thalassemia and abnormal hemoglobins in Sicily. The data derived from a total of 8875 beta-thalassemia alleles and 1330 variant hemoglobin chromosomes studied in Sicily from 1990 during a hemoglobinopathy control program. Fifty-four beta-globin gene defects were characterized, involving 30 different beta-thalassemia mutations and 24 variant hemoglobins. Eight of 30 β-thalassemia defects accounted for 95.11% of examined alleles while other beta-globin gene defects were found at lower frequencies (<1%). A consistent number (24) of variant hemoglobins were identified of whom Hb S was the most represented (72.1%). Our data underline the heterogeneity of the beta-globin gene defects in the Sicily. The enormous progress in the technique for β-globin gene analysis permitted to characterize 99.93% of mutated alleles and it has made a first trimester prenatal diagnosis program possible in our region in all cases with a great improvement in thalassemia management. The origin of the large spectrum of mutations is discussed taking in consideration the history of the island.     

A case of lymphoepithelial cyst of pancreas with unique “cheerios-like” appearance in EUS

Lymphoepithelial cyst (LEC) of the pancreas is a rare benign lesion, which is difficult to diagnose preoperatively. We describe a case of a 60-year-old male, incidentally diagnosed as having LEC of the pancreas, which was managed by laparoscopic distal pancreatectomy. Most of the reported cases of LEC were asymptomatic and diagnosed incidentally. A high index of suspicion under EUS may help in making a diagnosis and avoiding unnecessary surgery in asymptomatic patients. In particular, the unique ??cheerios-like?? appearance of the lesion in EUS, which was also found in this case, might be helpful in the differential diagnosis of pancreatic cystic lesions.