Genetic counseling and genetic heterogeneity in the thalassemias

In this study, we have compared the hemoglobin A2 levels (Hb A2) of alpha-thalassemia carriers (-alpha/-alpha and -alpha/alpha alpha genotypes) with those of double heterozygotes for delta+ and beta thalassemia genes, who were identified by family studies and polymorphic restriction site analysis within the beta-globin gene cluster. We found that double heterozygotes for the delta+ and beta thalassemia have significantly (p less than 0.001) higher Hb A2 levels as compared with carriers of alpha-thalassemia. This finding has practical implications in the genetic counseling of subjects with a thalassemia-like phenotype associated with normal or borderline Hb A2 levels.     

A new sickle cell disease phenotype associating Hb S trait,severe pyruvate kinase deficiency (PK Conakry), and an α2 globin gene variant (Hb Conakry)

A Guinean woman, hetererozygous for haemoglobin (Hb) S, was studied because of episodes of marked anaemia, repeated typical metaphyseal painful crises and haemosiderosis. Her sickling syndrome resulted from the association of Hb S trait with a severe pyruvate kinase deficiency leading to a 2,3-DPG concentration of twice normal levels. Sequence of the PK-R gene revealed an undescribed mutation in the homozygous or hemizygous state within exon 5 (nucleotide 2670 C → A), leading to the interchange of Ser 130 into Tyr (PK Conakry). In addition, the patient carried a new haemoglobin variant, Hb Conakry [α80(F1) Leu → Val], which seemed to have a mild effect. The high intraerythrocytic 2,3-DPG concentration induced by the PK deficiency resulted in a decreased oxygen affinity which favoured sickling to a level almost similar to that of Hb S/C compound heterozygous patients. This was confirmed by oxygen binding measurements of Hb A/Hb S erythrocytes in which 2,3-DPG content was modified in vitro. Hysteresis between deoxy- and reoxygenation curves, as well as increase in the n_max value, demonstrated that the extent of HbS polymerization in the propositus was almost the same as that of RBCs from a homozygous sickle cell patient or those of an A/S heterozygous patient with an artificial in vitro increase of 2,3-DPG concentration.     

Sickle cell anemia as a syndrome: a review of diagnostic features.

Sickle cell (SS) disease is a complex of various genetic conditions. In some, homozygosity for the beta S gene may be present alone or in combination with the heterozygous or homozygous alpha-thalassemia-2 condition. Such combinations might ameliorate the clinical and hematological condition of the patient. The same may be true for the high levels of Hb F and F-cells observed in many Hb S homozygotes. Howeever, the chemical heterogeneity of Hb F appears not to be related to the clinical status of the Hb S homozygote. Combinations of a Hb S heterozygosity with a heterozygosity for a Hb D-type of variant, for either one of two types of beta-thalassemia, two types of alpha beta- thalassemia, and five types of HPFH are discussed, and data are compared with those obtained for Hb S homozygotes. The use of advanced laboratory procedures and family studies is often necessary for an accurate diagnosis.     

Hemoglobin Villejuif [beta 123(H1) Thr----Ile]: a new variant found in coincidence with polycythemia vera

A new abnormal hemoglobin, Hb Villejuif [beta 123(H1) Thr----Ile] has been discovered during the exploration of a polycythemia in a 87-year-old patient of French origin. The isoelectric focusing of the lysate revealed the presence of a variant hemoglobin with an isoelectric point very close to that of HbA. The oxygen binding properties of the patient's red blood cells being normal, it was clear that the polycythemia was not a consequence of the presence of this hemoglobin. In fact, the red blood cell morphology and the involvement of the other blood cell lines, demonstrating excessive hemopoiesis, led to the diagnosis of polycythemia vera.     

Biotransformation of 4-dimethylaminophenol in the isolated perfused rat liver and in the rat

Isolated rat livers were perfused with various concentrations of 4-dimethylaminophenol-[¹⁴C] (DMAP). During single pass perfusion with modified protein-free Krebs-Henseleit solution up to 70μM prehepatic 4-dimethylaminophenol (DMAP) were metabolized by the liver. The main route of biotransformation was conjugation. At steady state conditions glucuronide formation showed an apparent V_max of 8.5 μmoles × min^?1 × g protein^?1, and K_m of 562 μM, whereas sulfate formation had an apparent V_max of 1.2 and a K_m of 35. Thus, at low substrate concentration the sulfate conjugation outweighed glucuronidation whereas at high substrate concentration the ratio of conjugates was reversed. In contrast to DMAP-sulfate, some DMAP-glucuronide was stored by the liver and was released with a half life of about 15 min which showed positive correlation with the dose of DMAP during the washout period. Perfusion with human or rat erythrocytes demonstrated the other important path of biotransformation of DMAP within erythrocytes, namely thioether formation with glutathione and SH-groups of hemoglobin. The pattern of DMAP-conjugation was affected depending on the time of prehepatic exposure to erythrocytes, and the species of red cells. The results obtained from the isolated metabolic system resemble the hepatic part of the overall metabolism under in vivo conditions.     

Eigenschaften des instabilen Hb Wien

Zusammenfassung Hb Wien besitzt als elektrophoretisch schnell wanderndes instabiles Hämoglobin im Vergleich zu manchen anderen instabilen Varianten einige abweichende Eigenschaften. Diese bestehen in kaum erhöhter Spontanoxydation und einem praktisch normalen Methämoglobinspektrum. Die in der Cyanmethämoglobinform nicht vom HbA₁ abweichende Hitzeempfindlichkeit ist wahrscheinlich auf den stabilisierenden Effekt der Ligandenbildung mit Cyanid zurückzuführen. Das fetale Hämoglobin entspricht quantitativ und in der intracellulären Verteilung anderen bei instabilen Varianten mitgeteilten Befunden. Das HbA₂ ist normal.     

Hemoglobin J Guantanamo [alpha 2 beta 2 128 (H6) Ala----Asp] in association with hemoglobin C and alpha-thalassemia in a family from Benin

Hemoglobin J (HbJ), Guantanamo, which had been described but once in the literature, was found in a family originating from Benin; this second case was found to be in association with hemoglobin C (HbC) and alpha-thalassemia. High-performance liquid chromatography (HPLC) procedures and microsequencing were used for characterization of the aminoacid substitution. The main hematological disorder, in relation with the instability of Hb J Guantanamo, seems to be a worsening of the rheological properties of the red blood cells (RBC), as demonstrated by ektacytometric studies. Oxygen-binding properties of the RBC were almost normal, but a slight decrease in cooperativity and lowered Bohr and 2,3-diphosphoglycerate (DPG) effects were observed for pure stripped Hb J Guantanamo. The expression of the electrophoretic charge difference was partly masked, as is often observed when the structural abnormality is situated in or near a contact area.     

Immunochemical estimation of haemoglobin types in red blood cells by FACS analysis

Summary. A fixation and permeabilization procedure using formaldehyde and acetone has been developed which allows immunostaining of intracellular haemoglobin for fluorescence activated cell sorter (FACS) analysis of erythrocytes. The treatment preserves antigenicity and light-scattering properties. Validation of the method was given by the correlation of F cell number in adults determined by FACS analysis with that assessed by microscopic examination of cell smears, and by the direct relationship between β chain synthesis and intensity of β chain/Hb A immunofluorescence within fetal erythrocyte samples known to vary in their β chain/Hb A content. The procedure is rapid, non-subjective and sensitive, and makes analysis of haemoglobin content, type and distribution amongst red cell populations possible.     

高海拔地区新生儿窒息与红细胞增多症的关系及微循环观察

目的：本文主要探讨新生儿窒息与红细胞增多症的关系及微循环流态变化；方法：对于国产期有窒息史或羊水污染的患儿于入院后２４小时做血细胞分析、血气分析及耳廓微循环流态观察；结果：窒息组Ｈｂ、ＨＣＴ、ＲＢＣ三项值明显高于对照组，８５便血气分析２７例代谢性酸中毒、１０例呼吸性酸中毒、１５例混合性酸中毒、６例低氧血症、１２例Ｉ型呼衰、８例Ⅱ型呼衰。４５例耳廓生循环观察、综合判断结果：中度异常２０例，轻度异常１     

Laboratory preparation and evaluation of a multiparameter hemocytometry control

A protocol for the laboratory preparation of a multiparameter hemocytometry control is given. Human platelets, stabilized by a basically simplified and inexpensive fixation procedure, are added to our previously described white and red blood cell control. Evaluation of this multiparameter control shows good precision characteristics and acceptable mechanical stability for at least 7 weeks, as measured in the Coulter counter Model S Plus-II. The control can basically contribute to the realization of the essence of internal quality control: continuous self-auditing and continuous attempts at improvement of performance.