German F Sáenz

Mutation analysis of glucose-6-phosphate dehydrogenase (G6PD) variants in Costa Rica

SummaryGlucose-6-phosphate dehydrogenase (G6PD) deficiency has previously been reported among both the black and white populations of Costa Rica. All 28 G6PD A — samples were found to be of the common G6PD A-376G/202Atype. A previously described mutation associated with nonspherocytic hemolytic anemia, G6PD Puerto Limón, was found to be due to a G→A transition at nucleotide (nt) 1192, causing a glu→lys substitution. Mutations in this region of the G6PD molecule seem invariably to be associated with chronic hemolytic anemia. G6PD Santamaria had been described previously in two unrelated white subjects. We found that both did, indeed, have the same mutations. In this variant the A→G substitution at nt 376 that is characteristic of G6PD A was present, but an A→T mutation at nt 542, apparently superimposed on the ancient G6PD A mutation, resulted in an asp→val substitution. Thus, the gain of a negative charge at amino acid 126 was counterbalanced by the loss of a charge at amino acid 181, giving rise to a variant with the G6PD A mutation but with normal electrophoretic mobility.

A Glucose-6-Phosphate Dehydrogenase Variant, Gd(-) Santamaria Found in Costa Rica

Red cell glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-chromosomal-linked abnormality often associated with hemolytic anemia. The G6PD variants obtained from 2 unrelated males, one associated with enzyme deficiency and history of hemolytic jaundice, and the other associated with enzyme deficiency but no hemolytic problems, were examined. Although the 2 subjects have no known consanguinity, the two enzymes could not be distinguished from each other in respect to their electrophoretic mobilities and kinetic properties, both exhibiting slower than normal anodal electrophoretic mobility, lower Km for G6P and NADP and higher rate of utilization of 2-deoxy-G6P and deamino-NADP. An unique double-banded pattern was observed in starch gel electrophoresis at pH 7.0 and pH 8.6. The variant is distinguished from all reported Gd variants, and it is designated Gd(-) Santamaria.

Hb Costa Rica or α2β277(EF1)His→Arg: The first example of a somatic cell mutation in a globin gene

Abstract We have identified a minor hemoglobin component (∼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 β77 (Hb Costa Rica). No other amino acid replacements were observed and no β- or γ-chain-like peptides were present. Hb Costa Rica has a normal stability. Sequence analyses of numerous polymerase chain reaction (PCR)-amplified segments of DNA that contain exon 2 of the β gene failed to identify a CAC→CGC (His→Arg) mutation. The same was the case when cDNA was sequenced, indicating that a β-Costa Rica-mRNA could not be detected with this procedure. Gene mapping of genomic DNA with BglII, 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 β chain variants Hb J-Iran and Hb Fukuyama with related mutations at β77 vary between 30% and 45% in heterozygotes, whereas that of Hb F-Kennestone with the same His→Arg mutation but in the Gγ-globin gene, is a high 40%–45% (as percentage of total Gγ) in a heterozygous newborn. These different observations exclude a heterozygosity of the A→G mutation at codon β77, as well as a deletion comparable to that of Hbs Lepore or Kenya, or a β-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.

G6PD-Puerto Limón: A new deficient variant of glucose-6-phosphate dehydrogenase associated with congenital nonspherocytic hemolytic anemia

SummaryA new glucose-6-phosphate dehydrogenase (G6PD) variant with total deficiency associated with congenital nonspherocytic hemolytic anemia was found in a Costa Rican family. The study of the partially purified enzyme revealed thermal instability, increased G6P affinity, abnormal pH optimum, increased utilization of analogues, and a chromatographic behavior that differs from all the variants previously described. Thus, this new variant was designated G6PD Puerto Limón.

Two Cases of Hemoglobin New York in Costa Rica

Hemoglobin New York was first described by Ranney et al. (1) in a Chinese American family. It was also reported in Chinese subjects in Taiwan by Blackwell et al. (2).

Hemoglobin Suresnes in a Costa Rican Woman of Spanish-Indian Ancestry

The first example of hemoglobin Suresnes, α2 141 (HC3) Arg → His β2, has recently been reported by Poyart et al (1). Hb Suresnes was detected by electrophoresis in a 6 year old boy who was found by routine hematological examination to have an abnormal RBC count and Hb concentration. The propositus and the two other members of the family who also had the variant did not show any clinical symptoms.