RESUMO
When first tested for abnormal hemoglobins, a 2-year-old boy, appeared to have Hb F, Hb S and Hb A2. Confirmatory testing revealed a beta chain variant inherited from his father and beta S from his mother. Analysis of tryptic peptides in conjunction with automated DNA sequence analysis showed that the variant hemoglobin was Hb Shelby [beta 131(H9)Gln-->Lys (CAG-->AAG)]. Heat and mechanical stabilities of various liganded Hb Shelby tetramers were compared to those of Hb A and Hb S. Oxy-Hb Shelby precipitated more readily than oxy-Hb A, but was much more stable than oxy-Hb S during mechanical agitation. In contrast, oxy-Hb Shelby was much less stable than oxy-Hb A and oxy-Hb S following heat treatment. Met-Hb Shelby was most unstable compared to other liganded forms of Hb Shelby, while deoxy- and carbonmonoxy-forms of Hb Shelby showed similar heat-induced precipitation rates. These data indicate that heat instability of Hb Shelby is accompanied by heme oxidation, and that denaturation by mechanical agitation occurs in the absence of heme oxidation. Hb Shelby, like Hb A, can form hybrids with Hb S which participate in polymer formation in vitro. However, Hb S/Hb Shelby hybrids copolymerized with Hb S less than A/S hybrids. Since the patient's MCHC value is normal, this finding coupled with the elevated Hb A2 and Hb F levels, both of which are known to inhibit polymerization of Hb S, may contribute to the patient's mild clinical presentation.
Assuntos
Globinas/genética , Hemoglobinas Anormais/genética , Traço Falciforme/genética , Sequência de Bases , Pré-Escolar , Feminino , Hemoglobina Falciforme/química , Heterozigoto , Temperatura Alta , Humanos , Ligantes , Masculino , Dados de Sequência Molecular , Polímeros , Desnaturação Proteica , Solubilidade , Estresse MecânicoRESUMO
A rapid, simple, nonradioactive method for detection of four common mutations causing cystic fibrosis (CF) has been developed combining multiplexing with allele-specific polymerase chain reaction amplification. This approach (MASPCR) provides an easy assay for direct genotyping of normal and mutant CF alleles in homozygotes and heterozygotes. The strategy involves multiplex PCR of exons 10, 11, and 21 within the cystic fibrosis transmembrane conductance regulator (CFTR) gene in a single reaction containing three common oligoprimers and either the four normal or four mutant oligos corresponding to the delta F508, G551D, G542X, and N1303K mutations. Primers are chosen so that the size of the four PCR products differ, thereby facilitating detection on agarose gels following amplification in the same reaction. Patient samples are primed with either four normal or four mutant oligo mixtures, and PCR products run in parallel on gels to detect band presence or absence. This approach provides a simple and potentially automated method for cost-effective population screening.
Assuntos
Fibrose Cística/genética , Proteínas de Membrana/genética , Mutação , Reação em Cadeia da Polimerase/métodos , Alelos , Sequência de Bases , Regulador de Condutância Transmembrana em Fibrose Cística , DNA de Cadeia Simples , Heterozigoto , Homozigoto , Humanos , Dados de Sequência Molecular , População Branca/genéticaRESUMO
We describe a new deletional form of gamma delta beta-thalassemia segregating in two generations of a family of Irish descent. Affected family members present with a beta-thalassemia minor phenotype, normal Hb A2 and Hb F levels. Genomic blotting analyses on DNA from affected family members show heterozygosity for a large deletion beginning at least 15 kb upstream of the 5' endpoint of the gamma delta beta-thalassemia-1 deletion, extending through the entire beta-like globin gene cluster, and continuing for at least 10 kb beyond the 3' endpoint of the deletion associated with the Spanish form of delta beta 0-thalassemia. This deletion is among the largest described so far, and removes at least 205 kb encompassing the entire beta-like globin gene cluster on chromosome 11.
Assuntos
Deleção Cromossômica , Cromossomos Humanos Par 11/ultraestrutura , Globinas/genética , Talassemia/genética , Adulto , Sondas de DNA , Feminino , Hemoglobina Fetal/análise , Hemoglobina A2/análise , Humanos , Recém-Nascido , Irlanda/etnologia , Icterícia Neonatal/etiologia , Masculino , Linhagem , Fenótipo , Polimorfismo de Fragmento de RestriçãoRESUMO
We describe a new deletional form of alpha thalassemia segregating in three generations of a family of northern European origin. A full-term female girl had hypochromic, microcytic anemia since early infancy associated with delayed language development, slow growth and weight gain. Hematologic studies suggested the presence of alpha thalassemia. Gene-blotting studies showed no abnormal alpha-like globin gene fragments; however, studies of inheritance of informative polymorphic restriction fragments using zeta, alpha and 3'-alpha-hypervariable region (3'-HVR) probes showed evidence for an extensive deletion encompassing the entire alpha-like globin gene cluster. The 3' breakpoint of this deletion maps beyond the 3'-HVR, a region implicated as a hot spot for the generation of other large deletional events within the alpha-like cluster. The 5' breakpoint maps at least 10 kilobases (kb) 5' to the zeta-globin gene. The minimum size estimate for this deletion is greater than 47 kilobases.
Assuntos
Deleção Cromossômica , Globinas/genética , Família Multigênica , Talassemia/genética , Pré-Escolar , Feminino , Alemanha , Hemoglobinas/análise , Humanos , Masculino , Linhagem , Polimorfismo de Fragmento de Restrição , Sequências Repetitivas de Ácido Nucleico , Mapeamento por Restrição , Talassemia/sangueRESUMO
Deformable sickle erythrocytes have been reported by Mohandas and Evans to be more adherent to vascular endothelium than rigid irreversibly sickled cells (ISC). To define the clinical implications of this finding we have determined genetic, hematological, clinical, and rheological characteristics of sickle erythrocytes obtained from 65 patients with sickle cell anemia and fetal hemoglobin (Hb F) levels less than 15%. The alpha-globin gene number had a significant effect on the hematological parameters, the percentage of dense cells, ISC number, and HB A2 levels. The presence or absence of alpha thalassemia, however, had no effect on the frequency and severity of the sickle cell painful crisis (r = 0.06, P greater than .05). RBC deformability, determined by an ektacytometer, showed great heterogeneity among patients with three or four alpha-globin genes. Linear regression analyses of the data showed significant positive correlation of the frequency and severity of the painful crisis with RBC deformability (r = 0.49, P less than .001), and negative correlations with the percentage of dense cells (r = -0.37, P = .002), and the percentage of ISC (r = -0.46, P less than .001). We propose that the more deformable the sickle RBC are, the greater their adherence to vascular endothelium, and the more they cause vaso-occlusive crises, RBC deformability and the percentage of dense cells (or ISC) seem to have a predictive value of the frequency and severity of painful crises in sickle cell anemia.
Assuntos
Anemia Falciforme/sangue , Deformação Eritrocítica , Eritrócitos Anormais/patologia , Dor/sangue , Adolescente , Adulto , Anemia Falciforme/complicações , Anemia Falciforme/genética , Criança , Eritrócitos Anormais/metabolismo , Feminino , Genes , Genótipo , Globinas/genética , Humanos , Masculino , Pessoa de Meia-Idade , Dor/etiologia , Análise de Regressão , ReologiaRESUMO
Seven patients, three males and four females, each with a single (unpaired) deciduous and permanent maxillary central incisor, were studied. All the males and two the female children were growth hormone deficient. One adult woman and a female infant with a single maxillary central incisor were short in stature but had normal growth hormone responses. No other dental anomalies or pituitary-hypothalamic dysfunctions were found. The dental anomaly was not familial. No eye abnormalitis were present in the patients or their families.