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Carrier Screening For Inherited Genetic Conditions
Published in Vincenzo Berghella, Obstetric Evidence Based Guidelines, 2022
Whitney Bender, Lorraine Dugoff
Alpha-thalassemia results from a gene deletion of two or more copies of the four alpha-globin genes on chromosome 16. It is common among individuals of Southeast Asian, African, West Indian, and Mediterranean ancestry. Deletion of two genes, alpha-thalassemia trait, causes a mild hemolytic anemia. The deletions may occur on the same chromosome (cis aa/-) or on two different chromosomes (trans a-/a-). Individuals of Southeast Asian descent are more likely to carry the cis configuration compared to their African counterparts. Individuals with alpha-thalassemia trait are at increased risk for having a child with a more severe form of alpha-thalassemia. Hemoglobin H disease is caused by the deletion of three alpha-globin genes. Affected individuals have mild to moderate hemolytic anemia. Alpha-thalassemia major (Hb Bart disease) results from the absence of functional alpha-globin genes. Fetal hydrops and intrauterine fetal demise is the expected outcome in these cases due to the inability to produce functional HbF. Hemoglobin Bart disease does not usually occur in fetuses of alpha-thalassemia carriers of African origin, since individuals of African descent usually have the trans-configuration genotype. See Chap. 14 in Maternal-Fetal Medicine Evidence Based Guidelines.
Ferrihemoglobin in Normal Blood
Published in Manfred Kiese, Methemoglobinemia: A Comprehensive Treatise, 2019
In hemolysates from human red cells with hemoglobin H (7%) kept for 24 hr in a refrigerator, 1.9% of the total hemoglobin was found in ferric form, whereas the proportion of ferrihemoglobin in hemolysates from normal red cell was below 1%.126 Hemoglobin H consists of four β-chains127 and shows an oxygen affinity ten times higher than hemoglobin A.128,129 Under air the proportion of deoxygenated ferrohemoglobin, which is of importance for the rate of autoxidation, must be very small.
The Red Blood Cell In Thalassemia *
Published in Ronald L. Nagel, Genetically Abnormal Red Cells, 2019
Eliezer Rachmilewitz, Ariella Oppenheim, Oded Shalev
The morphological appearance of thalassemic RBC is grossly abnormal. Since the amount of hemoglobin A per cell is less than normal, the cells appear poorly hemoglobinized displaying hypochromia and microcytosis, reminiscent of the RBC found in profound iron deficiency anemia. However, while the iron deficient RBC is also microcytic and hypochromic, the changes observed in thalassemic RBC include striking degrees of anisocytosis, from macrocytes to microcytes, poikilocytosis, numerous target cells, and basophilic stippling (Figure 2). In addition, one may observe some hemoglobinized normocytes or macrocytes, almost transparent hypochromic elliptocytes, small spherocytes, and spiculated cells together with variable numbers of tear drop and elongated forms and a great assortment of bizarre poikilocytes and distorted cell remnants. Moreover, erythroblasts which are never found in iron deficiency anemia are always present, their number correlating with the degree of the anemia.1 The various morphological changes are much more evident in RBC of patients with thalassemia major and intermedia after removal of the spleen.34 The most striking finding in severe cases is a large number of normoblasts reaching levels as high as 200 x 109/€.35 In addition, large, rather than small, hypochromic cells are found along with piscine forms which are little more than fragments of stroma. Morphological evidence for an expanded free α-chain pool in β-thalassemia was first obtained by light microscopy by Fessas36 who described cytoplasmic inclusion bodies within both nucleated RBC and reticulocytes. The inclusions, which resemble Heinz bodies,37 can be easily detected if the cells are first incubated with the supravital stain methyl violet. In subsequent studies Fessas et al. isolated and partially purified the inclusion bodies from the peripheral blood and revealed by peptide mapping that they consisted of hemoglobin-like material in which the protein is composed predominantly, if not exclusively, of precipitated α chains.38,39 Analysis of marrow aspirated from individuals with β-thalassemia major and intermedia indicated that the proportion of erythroblasts containing intracellular precipitates and the average quantity of precipitation per affected cell increased with increasing nuclear diameter.40 It was concluded that α-chain precipitation commences early during erythroid maturation and the amount of the precipitated chains increases with increasing cellular maturity. This observations is in agreement with the fact that α chains, unlike β chains, are more unstable and cannot form a homotetramer of the type α4, similar to β4 (Hemoglobin H).
Successful four-factor preimplantation genetic testing: α- and β-thalassemia, human leukocyte antigen typing, and aneuploidy screening
Published in Systems Biology in Reproductive Medicine, 2021
Dongjia Chen, Xiaoting Shen, Yan Xu, Chenhui Ding, Qingjian Ye, Yiping Zhong, Yanwen Xu, Canquan Zhou
Patients with dual β-thalassemia mutations have β-thalassemia major and often cannot survive to child-bearing age. Patients with two types of α-thalassemia mutations, however, can experience mild-to-moderate anemia or hemoglobin H (HbH) disease, thereby having a longer life expectancy and reproductive capability than those with dual β-thalassemia mutations. When couples are carriers of α- and β-double thalassemia with a single α-thalassemia mutation, such as these three families, the probability of achieving a transferable embryo is 0.75 × 0.75 = 56.25%. In our study, the probability was close to the theoretical value at 51.5% (17/33). However, if one partner of each couple was HbH or carried two types of α-thalassemia mutations, the probability would decrease to 0.5 × 0.75 = 37.5%. Certainly, the probability would reduce by a quarter when combined with HLA typing, further declining when combined with PGT-A. For example, when combining PGT for two types of thalassemia and aneuploidy screening, Family 2 achieved no transferable embryo. To provide a large number of embryos for biopsy, poor responders generally need to undergo several ovarian stimulation cycles. If no blastocyst with matched HLA is obtained, patients may choose to transfer unaffected euploid embryos or reenter new PGT cycles.
Epidemiologic study of major complications in adolescent and adult patients with thalassemia in Northeastern Thailand: the E-SAAN study phase I
Published in Hematology, 2018
Nattiya Teawtrakul, Arunee Jetsrisuparb, Saranya Pongudom, Chittima Sirijerachai, Kanchana Chansung, Chinadol Wanitpongpun, Supan Fucharoen
Genotype group classification including; β-thalassemia/hemoglobin E defined as the presence of β-gene mutation(s) and hemoglobin E by hemoglobin type testing and or the DNA analysis.Combined α and β-thalassemia defined as the group of patients with Hb H disease, compound heterozygous Hb H and heterozygous Hb E (EABart’s disease), compound heterozygous Hb H and homozygous Hb E (EFBart’s disease), compound heterozygous Hb H with Hb CS and heterozygous Hb E (EABart’s disease with Hb CS), compound heterozygous Hb H with Hb CS and homozygous Hb E (EFBart’s disease with Hb CS), compound heterozygous Hb H with Hb Pakséand heterozygous Hb E (EABart’s disease with Hb Paksé).α-thalassemia defined as the group of patients with hemoglobin H (Hb H) disease with hemoglobin Constant Spring (Hb CS), Hb H disease with hemoglobin Paksé (Hb Paksé).
Detecting rare thalassemia in children with anemia using third-generation sequencing
Published in Hematology, 2023
Zhen-min Ren, Wu-jiao Li, Zhi-hao Xing, Xiao-ying Fu, Ju-yan Zhang, Yun-sheng Chen, De-fa Li
In addition to the TDT case, TGS confirmed one case of severe non-deletional HbH disease (–SEA/α−91α). HbH disease is divided into deletional and non-deletional types, with the non-deletional type being more severe [13,14]. In this study, –SEA/α−91α corresponded to the non-deletional type of HbH disease, characterized by splenomegaly and blood transfusion dependence since infancy. However, the –SEA/αCD30α in this study only presented mild anemia, consistent with a report by Chen et al. [15], but not with another report by Ma et al. [16]. The heterogeneity of hemoglobin H disease may be related to race or modified genes, requiring further research.