The molecular basis of beta thalassaemia in Punjabi and Maharashtran Indians includes a multilocus aetiology involving triplicated alpha-globin loci. 1994

G Garewal, and C W Fearon, and T C Warren, and N Marwaha, and R K Marwaha, and C Mahadik, and H H Kazazian
Center for Medical Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland.

We have analysed 201 beta-thalassaemia (beta-thal) genes from natives of the Punjab (156) and Maharashtra states of India and found the causative mutation in 200 of them. The most common beta-globin gene mutations differed significantly between these two groups and between these groups and Indian immigrants in the U.S.A. and the U.K. In the Punjabi Indians the IVS-1, nt 1 (G-T) mutation accounted for nearly one-quarter of beta-thal genes, whereas it was 5% or less in the other groups. Likewise, the cap + 1 mutation was much more prevalent in the Punjabis, whereas the nonsense codon 15 allele had a higher frequency in the Maharashtrans of the Bombay region. The common IVS-1, nt5 allele had a frequency of 60% of beta-thal genes in the Maharastrans, 35% in North American immigrants, and only 23% in the Punjabis. Two-thirds of all beta-thal genes in Punjab were found in the merchant caste (Khatri-Arora), whereas the menial caste (Shudra) was highly represented among those with beta-thal genes in Maharashtra. Two novel beta-globin alleles were each found once; a frameshift codon 55 (+A) in Maharashtrans and a frameshift codons 47-48 (+ATCT) in Punjabis. Of three Punjabi patients with beta-thal intermedia in whom only a single severe beta-globin gene mutation was found, two had six alpha-globin genes (homozygosity for a triplicated alpha-globin locus) instead of the normal alpha-globin gene number of four. Thus, these two individuals had a multilocus aetiology of beta-thal and their parents have the unusual recurrence risk of 1 in 8 for conceiving a third with beta-thal intermedia. Since 15% of 126 alpha-globin clusters studies in Punjabis contained either single (10%) or triplicated (5%) alpha-globin genes, the alpha-globin gene number is a frequent modifier of the phenotype of beta-thal in this ethnic group.

UI MeSH Term Description Entries
D007194 India A country in southern Asia, bordering the Arabian Sea and the Bay of Bengal, between Burma and Pakistan. The capitol is New Delhi. Republic of India
D008297 Male Males
D009154 Mutation Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations. Mutations
D005260 Female Females
D005810 Multigene Family A set of genes descended by duplication and variation from some ancestral gene. Such genes may be clustered together on the same chromosome or dispersed on different chromosomes. Examples of multigene families include those that encode the hemoglobins, immunoglobulins, histocompatibility antigens, actins, tubulins, keratins, collagens, heat shock proteins, salivary glue proteins, chorion proteins, cuticle proteins, yolk proteins, and phaseolins, as well as histones, ribosomal RNA, and transfer RNA genes. The latter three are examples of reiterated genes, where hundreds of identical genes are present in a tandem array. (King & Stanfield, A Dictionary of Genetics, 4th ed) Gene Clusters,Genes, Reiterated,Cluster, Gene,Clusters, Gene,Families, Multigene,Family, Multigene,Gene Cluster,Gene, Reiterated,Multigene Families,Reiterated Gene,Reiterated Genes
D005914 Globins A superfamily of proteins containing the globin fold which is composed of 6-8 alpha helices arranged in a characterstic HEME enclosing structure. Globin
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000483 Alleles Variant forms of the same gene, occupying the same locus on homologous CHROMOSOMES, and governing the variants in production of the same gene product. Allelomorphs,Allele,Allelomorph
D016133 Polymerase Chain Reaction In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships. Anchored PCR,Inverse PCR,Nested PCR,PCR,Anchored Polymerase Chain Reaction,Inverse Polymerase Chain Reaction,Nested Polymerase Chain Reaction,PCR, Anchored,PCR, Inverse,PCR, Nested,Polymerase Chain Reactions,Reaction, Polymerase Chain,Reactions, Polymerase Chain
D017086 beta-Thalassemia A disorder characterized by reduced synthesis of the beta chains of hemoglobin. There is retardation of hemoglobin A synthesis in the heterozygous form (thalassemia minor), which is asymptomatic, while in the homozygous form (thalassemia major, Cooley's anemia, Mediterranean anemia, erythroblastic anemia), which can result in severe complications and even death, hemoglobin A synthesis is absent. Anemia, Cooley's,Anemia, Erythroblastic,Anemia, Mediterranean,Hemoglobin F Disease,Thalassemia Major,Thalassemia Minor,Erythroblastic Anemia,Mediterranean Anemia,Microcytemia, beta Type,Thalassemia Intermedia,Thalassemia Major (beta-Thalassemia Major),Thalassemia Minor (beta-Thalassemia Minor),Thalassemia, beta Type,beta Thalassemia,Anemia, Cooley,Anemia, Cooleys,Anemias, Erythroblastic,Anemias, Mediterranean,Cooley's Anemia,Disease, Hemoglobin F,Intermedia, Thalassemia,Intermedias, Thalassemia,Major, Thalassemia (beta-Thalassemia Major),Majors, Thalassemia (beta-Thalassemia Major),Mediterranean Anemias,Microcytemias, beta Type,Minor, Thalassemia (beta-Thalassemia Minor),Minors, Thalassemia (beta-Thalassemia Minor),Thalassemia Intermedias,Thalassemia Major (beta Thalassemia Major),Thalassemia Majors (beta-Thalassemia Major),Thalassemia Minor (beta Thalassemia Minor),Thalassemia Minors (beta-Thalassemia Minor),Thalassemia, beta,Thalassemias, beta,Thalassemias, beta Type,Type Microcytemia, beta,Type Microcytemias, beta,Type Thalassemia, beta,Type Thalassemias, beta,beta Thalassemias,beta Type Microcytemia,beta Type Microcytemias,beta Type Thalassemia,beta Type Thalassemias

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