Carol West

Ferroportin 1 (SCL40A1) variant associated with iron overload in African-Americans.

We find that in the Black American population average ferritin levels are higher than those in Whites, both among men and women. African-Americans have an increased prevalence of iron storage disease characterized by prominent iron deposition in macrophages of the liver and other organs. The iron distribution in patients with mutations of the ferroportin gene is similar. A c.744 G-->T (Gln 248 His) mutation was detected among African-Americans at polymorphic frequencies. This variant is associated with increased ferritin levels in African-Americans and may play a role in their propensity to develop iron overload.

Genotypic and phenotypic heterogeneity of African Americans with primary iron overload

Primary iron overload may be relatively common in African Americans, but its cause is incompletely understood. Thus, we evaluated genotype and phenotype characteristics of unselected African American index patients with primary iron overload who reside in central Alabama. All had hepatic iron concentration > or =30 micromol/g dry wt or > or =2.0 g of iron mobilized by phlebotomy to achieve iron depletion. Genotype analyses were performed in African American control subjects from the same region. There were 23 patients (19 men, 4 women); mean age at diagnosis was 52 +/- 12 years (1 SD) (range 32-69 years). Nine (39.1%) reported that they consumed > or =45 g of ethanol daily; five had chronic hepatitis C. Eight had some form of hemoglobinopathy or thalassemia. Mean serum transferrin saturation was 56 +/- 28% (range 15-100%). The geometric mean serum ferritin at diagnosis was 1076 ng/mL [95% confidence interval 297-3473 ng/mL]. Increased stainable liver iron was observed in hepatocytes only in 4 patients, in macrophages only in 8 patients, and in hepatocytes and macrophages in 8 patients. The mean quantity of iron mobilized by phlebotomy (corrected for iron absorbed during treatment) was 5.3 +/- 2.0 g (range 4.0-8.4 g). Iron removed by phlebotomy was greater in patients with hemoglobinopathy or thalassemia than in those without these forms of anemia (6.6 +/- 1.3 g vs 3.9 +/- 1.6 g, respectively; P = 0.0144). Daily consumption of > or =45 g of ethanol or chronic hepatitis C was not associated with an increased or decreased amount of phlebotomy-mobilized iron, on the average. The percentage of index patients positive for HFE C282Y was greater than that of controls (P = 0.0058). The respective percentages of phenotype positivity for HFE H63D, D6S105(8), and HLA-A*03 were similar in patients and controls. HFE S65C, I105T, and G93R were not detected in index or control subjects. Two of 13 patients were heterozygous for the ferroportin allele nt 744 G-->T (Q248H), although the phenotype frequency of this allele was similar in patients and 39 controls. Synonymous ferroportin alleles were also detected in some patients. The ceruloplasmin mutation nt 1099C-->T (exon 6; Arg367Cys) was detected in 1 of 2 patients tested. Abnormal alleles of beta-2 microglobulin, Nramp2, TFR2, hepcidin, or IRP2 alleles were not detected in either of the 2 patients so tested. We conclude that primary iron overload in African Americans is not the result of the mutation of a single gene. HFE C282Y, ferroportin 744 G-->T, and common forms of heritable anemia appear to account for increased iron absorption or retention in some patients.

A previously undescribed nonsense mutation of the HFE gene

A patient with clinically manifest hereditary hemochromatosis was found to be heterozygous for the c.845 A→G (C282Y) mutation. As simple heterozygotes for this mutation do not develop the hemochromatosis phenotype, the coding region of the patients HFE gene was sequenced and a previously undescribed nonsense mutation was identified at c.211 C→T (R74X). The patients brother who also had the hemochromatosis phenotype shared his HFE genotype. To determine how common such mutations might be, the coding and 5′ region of the HFE genes of 11 subjects who had been found in a large population survey to be heterozygous for the C282Y mutation and had elevated ferritin levels were sequenced. No mutations were found. Sequencing of the HFE gene also revealed two polymorphisms that had not previously been noted, − 467 C→G and − 970 T→G. Neither of these mutations appear to cause an abnormality in iron metabolism.

Prevalence of Glucose-6-Phosphate Dehydrogenase Deficiency in Sickle-Cell Disease

Abstract Glucose-6-phosphate dehydrogenase genotypes were determined in 24 male patients with sickle-cell disease from 21 families and from 24 male sibs, including at least one from each family. Th...

Electrophoretic polymorphism of glutathione peroxidase

A method for the detection of glutathione peroxidase after electrophoresis on starch gel has been devised. Blood samples from 780 persons of Caucasian or Negro origin were studied. An electrophoretically fast enzyme, designated as the Thomas variant, was found in 6·4 % of 392 Negro donors and 0·8 % of 388 Caucasian donors. This variant was inherited in an autosomal dominant fashion. A slightly rapid electrophoretic mobility was noted in some cord blood samples and in a father and daughter with a refractory anaemia. Because this variant, designated ‘Musi’ differed so little from the normal variant, it was difficult to further characterize it, but it did not appear that this variant was genetically determined.

Genetic polymorphisms and susceptibility to lung disease

Susceptibility to infection by bacterium such as Bacillus anthracis has a genetic basis in mice and may also have a genetic basis in humans. In the limited human cases of inhalation anthrax, studies suggest that not all individuals exposed to anthrax spores were infected, but rather, individuals with underlying lung disease, particularly asthma, sarcoidosis and tuberculosis, might be more susceptible. In this study, we determined if polymorphisms in genes important in innate immunity are associated with increased susceptibility to infectious and non-infectious lung diseases, particularly tuberculosis and sarcoidosis, respectively, and therefore might be a risk factor for inhalation anthrax. Examination of 45 non-synonymous polymorphisms in ten genes: p47phox (NCF1), p67phox (NCF2), p40phox (NCF4), p22phox (CYBA), gp91phox (CYBB), DUOX1, DUOX2, TLR2, TLR9 and alpha 1-antitrypsin (AAT) in a cohort of 95 lung disease individuals and 95 control individuals did not show an association of these polymorphisms with increased susceptibility to lung disease.

A previously undescribed frameshift deletion mutation of HFE (c.del277; G93fs) associated with hemochromatosis and iron overload in a C282Y heterozygote.

A 62‐year‐old white man with a hemochromatosis phenotype was found to be heterozygous for the C282Y mutation of the HFE gene. The H63D and S65C mutations of HFE were not present. As most C282Y heterozygotes do not develop a hemochromatosis phenotype, the coding region of the patients HFE gene was sequenced and a previously undescribed frameshift mutation was identified in exon 2 (c.del277; G93fs) that resulted in a premature stop‐codon. There were no coding region mutations of the ferroportin gene (FPN1). We performed human leukocyte antigen (HLA) typing of the patient and his brother who was heterozygous for the C282Y HFE mutation unassociated with a hemochromatosis phenotype. They shared only C282Y and the HLA haplotype A*03, B*14; hence, the c.del277 mutation was linked to the HLA haplotype A*02, B*44 and therefore not on the same chromosome as the C282Y mutation. Thus, the present patients only intact HFE protein is C282Y, and this may explain his hemochromatosis phenotype.

Erythrocyte viability in blood salvaged during total joint arthroplasty with cement.

Background: Erythrocyte salvage, the collection of a patient’s blood shed from the surgical wound, is one aspect of blood management. Previous investigators have examined salvaged blood for content; however, to our knowledge, none have examined the viability of erythrocytes after exposure to the chemical and thermal reactions produced by motorized instruments and polymethylmethacrylate during surgery. The purpose of this study was to determine the viability of salvaged erythrocytes from patients undergoing primary total joint arthroplasty with cement. Methods: Erythrocyte viability studies were performed on specimens from three subjects with use of a double isotope-labeling technique employing chromium-51 and technetium-99m. With use of a fresh blood specimen obtained prior to surgery and a specimen of salvaged blood that had been recycled, washed, and filtered with use of the Cell Saver, the viability of the Cell-Saver-processed erythrocytes, labeled with chromium-51, was calculated on the basis of the technetium-99m-labeled red blood-cell mass. Results: The mean erythrocyte viability (and standard deviation) in blood salvaged with use of the Cell Saver was 88.0% ± 3.8%. The standard of the American Association of Blood Banks for minimum erythrocyte viability in adequately cross-matched allogeneic blood or predeposited autologous blood is 70%. Conclusions: The high rate of viability of the erythrocytes in this study shows that the Cell Saver is a valuable adjunct to other blood management techniques for patients having total joint arthroplasty. We believe that the very high mean rate of erythrocyte viability and the extremely small standard deviation in our three subjects, as compared with the standards of the American Association of Blood Banks, made additional study subjects unnecessary.

SLC40A1 c.1402G→A Results in Aberrant Splicing, Ferroportin Truncation after Glycine 330, and an Autosomal Dominant Hemochromatosis Phenotype

Background/Aims: To determine the molecular basis of a mild hemochromatosis phenotype in a man of Scottish-Irish descent. Methods: We sequenced genomic DNA to detect mutations of HFE, SLC40A1, TFR2, HAMP, and HFE2. RNA isolated from blood mononuclear cells was used to make cDNA. RT-PCR was performed to amplify ferroportin from cDNA, and amplified products were visualized by electrophoresis and sequenced. Results: The proband was heterozygous for the novel mutation c.1402G→A (predicted G468S) in exon 7 of the ferroportin gene (SLC40A1). Located in the last nucleotide before the splice junction, this mutation results in aberrant splicing to a cryptic upstream splice site located at nt 990 within the same exon. This causes truncation of ferroportin after glycine 330 and the addition of 4 irrelevant amino acids before terminating. The truncated ferroportin protein, missing its C-terminal 241 amino acids, would lack all structural motifs beyond transmembrane region 7. The patient was also heterozygous for the common HFE H63D polymorphism, but did not have coding region mutations in TFR2, HAMP, or HFE2. Conclusions: We conclude that this patient represents a unique example of hemochromatosis due to a single base-pair mutation of SLC40A1 that results in aberrant splicing and truncation of ferroportin.

Glucose-6-phosphate dehydrogenase variants in the chimpanzee☆

Abstract Blood samples from 29 male and 25 female chimpanzees were examined for G-6-PD activity and electrophoretic mobility. Wild-type chimpanzee G-6-PD had a slightly slower electrophoretic mobility than human G-6-PD. Fast and slow variants of chimpanzee G-6-PD were detected both by starch gel electrophoresis and by gel isoelectric focusing. The chimpanzees with the slow G-6-PD phenotype had a lower enzyme activity than those with the wild type. Only a single animal heterozygous for the fast type of G-6-PD was found, and although its activity was lower than average, no conclusion could be drawn. The existence of two types of enzyme in some females, but not in males, is consistent with sex linkage of G-6-PD in chimpanzees.