Hb Lepore Washington-Boston in two Mexican mestizo families.

Two Mexican mestizo families with Hb Lepore Washington-Boston are described. One family is from Cordova, in the State of Veracruz, in the East coast of Mexico: the proband is a 44-year old asymptomatic male with italian ancestors; the other family is from the city of Durango, State of Durango, in the northwestern part of the country: the propositus is a 32-year old pregnant female with French ancestors. In both cases the Hb Lepore was identified by alkaline electrophoresis and characterized by high performance liquid chromatography and PCR with specific probes flanking the deletion frame. The beta-haplotype in both families was +(-)-(-)-(++), the commonest beta-haplotype reported with this mutation. This paper describes the first cases of this entity in Mexico.

Hydroxyurea therapy in sickle cell anemia patients in Curaçao, The Netherlands Antilles.

We have treated 9 patients with sickle cell anemia (SS) with hydroxyurea (HU). All 9 patients carried 4 alpha-globin genes and the beta s-globin haplotypes 19/19 (Benin/Benin), except for 1 who had haplotype 19 together with type 3 (Benin/Senegal). Six patients received HU for 10 months and were again treated with the drug for 5 months after an interval of 1 year. One patient was given HU for 22 consecutive months. A record was kept of hematological and biochemical data, Hb F and G gamma levels, as well as possible clinical complications. Our data show that HU generally improves the hematological and biochemical values and the level of Hb F, and reduces painful crises in some patients. However, although the clinical symptoms improved in some patients during HU therapy, the older patients did not observe any changes in their general condition; the same is the case for the patient with haplotype 19/3. One patient also experienced life-threatening liver sequestration during treatment. We conclude that the selection of patients who may benefit from HU therapy needs further evaluation.

The relative levels of different types of beta-mRNA and beta-globin in BFU-E derived colonies from patients with beta chain variants; further evidence for somatic mosaicism in the Hb Costa Rica carrier [beta 77(EF1)His-->Arg].

We have identified and quantitated the different types of mRNA in single BFU-E derived colonies from Hb S and Hb Atlanta [beta 75 (E19)Leu-->Pro] heterozygotes and observed that the normal and mutated mRNAs were present in equal quantities. Similar studies for the different protein products gave less accurate data because high performance liquid chromatography methods were not sensitive enough for the analysis of a single colony, and as many as five colonies needed to be combined. The level of Hb S (approximately 40%) was the same as in red cell lysates of the Hb S heterozygote, while that of the unstable beta-Atlanta chain was lower than expected from the values observed in red cells. Similar studies for a carrier of the stable Hb Costa Rica [beta 77(EF1) His-->Arg] which was reported to be the result of a somatic cell mutation (1) gave quite different data. Dot-blot analysis with 32P-labeled probes and allele specific amplification methodology identified numerous colonies with beta A-mRNA only, while 12-15% of the colonies contained both beta A- and beta-Costa Rica-mRNA. This limited distribution of the beta-Costa Rica-mRNA was confirmed by hemoglobin analysis with anion exchange high performance liquid chromatography. These results are considered to provide additional and convincing evidence for a somatic mosaicism for the CAC-->CGC mutation at codon 77 of the beta gene which occurred during the development of the embryo and results in the presence of only some 6-8% of the abnormal Hb Costa Rica in the circulating red cells.

Hb Costa Rica or alpha 2 beta 2 77(EF1)His --> Arg: the first example of a somatic cell mutation in a globin gene.

We have identified a minor hemoglobin component (approximately 5%) in the blood of a healthy Costa Rican female, but not in her mother and two brothers (father not studied), that has an His --> Arg replacement at position beta 77 (Hb Costa Rica). No other amino acid replacements were observed and no beta- or gamma-chain-like peptides were present. Hb Costa Rica has abnormal stability. Sequence analyses of numerous polymerase chain reaction (PCR)-amplified segments of DNA that contain exon 2 of the beta gene failed to identify a CAC --> CGC (His --> Arg) mutation. The same was the case when cDNA was sequenced, indicating that a beta-Costa Rica-mRNA could not be detected with this procedure. Gene mapping of genomic DNA with Bg/II, BamHI, and HindIII gave normal fragments only and with the same intensity as observed for the fragments of a normal control. The quantities of the beta chain variants Hb J-Iran and Hb Fukuyama with related mutations at beta 77 vary between 30% and 45% in heterozygotes, whereas that of Hb F-Kennestone with the same His --> Arg mutation but in the G gamma-globin gene, is a high 40%-45% (as percentage of total G gamma) in a heterozygous newborn. These different observations exclude a heterozygosity of the A --> G mutation at codon beta 77, as well as a deletion comparable to that of Hbs Lepore or Kenya, or a beta-globin gene duplication, and point to a nontraditional inheritance of Hb Costa Rica. Allele-specific amplification of cDNA with appropriate primers identified the presence of a low level of mutated mRNA in the reticulocytes of the patient, which was confirmed by dotblot analysis of the same material with 32P-labeled probes. Comparable amplification products were not observed in genomic DNA. The A --> G mutation apparently occurred in a somatic cell at a relatively early stage in the development of the hematopoietic cell system, and Hb Costa Rica accumulated through rapid cell divisions in patchy areas in the bone marrow (somatic mosaicism). An unequal distribution of Hb Costa Rica over the red cells supports this possibility.

Compound heterozygosity for a mild beta (+) and a rare beta(0)-thalassemia allele.

Hematological and hemoglobin composition data are presented for 14 members of a Surinam family (and for 1 unrelated subject) with either a beta-thalassemia heterozygosity [5 with the -29 (A----G) beta + mutation and 5 with the IVS II-849 (A----G) beta(0) mutation] or a compound heterozygosity (the 5 remaining patients). Identification of the mutation was by hybridization of amplified DNA with 32P-labelled synthetic oligonucleotides. The data indicate distinct differences between the two groups of heterozygotes, mainly in degree of microcytosis and hypochromia, in Hb A2 level, and in the level of G gamma (high in the -29 heterozygotes and low in the IVS II-849 heterozygotes). The 5 compound heterozygotes had a thalassemia intermedia with high Hb F levels (high G gamma), elevated Hb A2, and Hb A levels comparable to those seen in patients with a homozygosity for the -29 mutation or with the combination of this beta(+)-thalassemia and Hb S. An alpha-thalassemia-2 heterozygosity (-3.7 kb deletion) was present in 2 patients. Their hematological data were improved over those for the patients with four alpha globin genes; one was the mother of two sets of twins. The high G gamma value in the Hb F of the compound heterozygotes suggests that the high Hb F production in the condition is mainly directed by the chromosome with the -29 (A----G) mutation.

Hb Chad or alpha 223(B4)Glu----Lys beta 2 observed in members of a Surinam family in association with alpha-thalassemia-2 and with Hb S.

Three different hemoglobinopathies, i.e. Hb S, Hb Chad [alpha 23 (B4)Glu----Lys], and alpha-thalassemia-2 (-3.7) have been observed in eight members of a family from Surinam. The proposita had all three abnormalities, while her mother and four of her half-brothers had Hb Chad together with an alpha-thalassemia-2 heterozygosity or homozygosity. Gene mapping and dot-blot analysis of amplified DNA identified a G----A mutation in codon 23 of the alpha 2 alpha 1 hybrid gene resulting in the Glu----Lys substitution. The quantity of the alpha-Chad chain averaged 31.5% in its carriers with an additional alpha-thalassemia-2 heterozygosity [-alpha Chad(-3.7 kb)/alpha alpha], and 43% in the two carriers with an additional alpha-thalassemia-2 homozygosity [-alpha Chad (-3.7 kb)/-alpha (3.7 kb)]. These quantities are considerably higher than those reported for families from Chad, China, and Japan; the low levels of 14.5-24% Hb Chad in members of previously reported cases suggest a mutation on a chromosome with two alpha-globin genes [alpha alpha Chad/alpha alpha or alpha Chad alpha/alpha alpha].

Hb F-Bonaire-Ga or alpha 2 A gamma 2 39(C5) Gln replaced by Arg, characterized by high pressure liquid chromatographic and microsequencing procedures.

A slowly moving gamma chain variant was discovered in the cord blood of a baby of English-Vietnamese descent. The abnormality concerned the substitution of Gln residue in position 39(C5) of the A gamma chain by an Arg residue resulting in an -Arg-Arg- sequence at positions 39 and 40. The quantity of the A gamma chain variant was nearly 10% of the total Hb F with 15% of the Hb F having normal A gamma chains and 75% of Hb F having G gamma chains. High pressure liquid chromatographic and microsequencing methods greatly facilitated the structural analyses.

Heterozygosity and homozygosity for the high oxygen affinity hemoglobin Tarrant or alpha 126 (H9) Asp replaced by Asn in two Mexican families.

Two Mexican families from the State of Jalisco have been studied in which 11 members were carriers of Hb Tarrant. Ten subjects were Hb Tarrant heterozygotes producing about 25% of the abnormal hemoglobin. One 9-year-old boy was homozygous for Hb Tarrant. About 50% of his hemoglobin was of the variant type. The heterozygotes had mild erythrocytosis which was considerably more severe in the homozygote. The average P50 value for blood of the heterozygote was 15.1 mm Hg (controls: 22.5 mm Hg) while this value was decreased to 9 mm Hg in the homozygote. The clinical condition of the homozygote is compatible with a mild chronic tissue hypoxia.

Delta beta-thalassemia in a Mexican family: clinical differences among homozygotes.

Three delta beta-thalassemia homozygotes were found in a Mexican family. Both parents and two sibling had heterozygous delta beta-thalassemia with about 10% Hb F, mild microcytosis and mild hypochromia, while three siblings were normal. Hb F, which was the only Hb component in the homozygotes, had equal quantities of Ggamma and Agamma chains as in BgammaAgamma-delta beta-thalassemia. The homozygotes had comparable erythrocytic indices which were about the same as those of the heterozygotes. However, two were clinically and hematologically healthy but the third had a severe chronic hemolytic anemia and a more severe in vitro chain synthesis imbalance than her homozygous sisters. Comparison of these cases with other GgammaAgamma-delta beta-thalassemia homozygotes and with GgammaAgamma-HPFH homozygotes indicates the possibility that the proliferation of F-cell precursors may be defective in delta beta-thalassemia.