Identification of deletion and triple alpha-globin gene haplotypes in the Montreal beta-thalassemia screening program: implications for genetic medicine
| Autor: | Charles R. Scriver, T M Fujiwara, B R Akerman, G A Lancaster, Kenneth Morgan |
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| Rok vydání: | 1990 |
| Předmět: |
Adult
Erythrocyte Indices Male Adolescent Genotype Thalassemia Genetic Carrier Screening Alpha (ethology) Biology hemic and lymphatic diseases medicine Humans Mass Screening Globin Hemoglobin A2 Child Genetics (clinical) Mass screening Genetics Haplotype Quebec Infant DNA Middle Aged medicine.disease Globins Hemoglobinopathy Phenotype Haplotypes Child Preschool Female Chromosome Deletion |
| Zdroj: | American journal of medical genetics. 36(1) |
| ISSN: | 0148-7299 |
| Popis: | We obtained blood samples in a screening program designed to detect beta-thalassemia heterozygotes in Montreal; additional samples were obtained from referred persons. We analyzed DNA for variant numbers of alpha-globin genes, notably the alpha-thalassemia2 (-alpha/), alpha-thalassemia1, (- -/), and triplicated alpha-globin gene (alpha alpha alpha/) haplotypes using restriction enzymes and probes for alpha-globin and zeta-globin gene sequences. We estimated the numbers of Montreal residents of Italian and Greek ethnic origin with -alpha/alpha alpha genotype. Thus, 4.3% of Italians and 1.5% of Greeks, or about 7,500 persons, are estimated to be alpha-thalassemia2, trait (silent carriers), largely (80%) in the -alpha 3.7/type I form. The triplicated alpha-globin gene haplotype was also found. The risk of a severe (alpha-thalassemia1) phenotype associated with inheritance of - -/alpha alpha or -alpha/-alpha genotypes was low and was found predominantly in this study, in persons of Asian ethnic origin. The sample of Asians was too small to estimate carrier frequencies; however, based on results from the beta-thalassemia screening program, we estimated that about 4% of Asians (about 1,300 persons) in Montreal are alpha-thalassemia carriers. We identified persons heterozygous for both beta-thalassemia and alpha-thalassemia mutations. In these double heterozygotes, the effect of the triplicated alpha-globin gene was to make the erythrocyte parameters used for screening (MCV and %HbA2) more deviant from normal whereas deletion of 2 alpha-globin genes tended to normalize the erythrocyte values. These findings have implications for the screening program and reproductive counseling. |
| Databáze: | OpenAIRE |
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