Two Haemoglobins Q, α74 (EF3) and α75 (EF4) Aspartic Acid→Histidine

Lorkin, P. A.; Charlesworth, Deborah; Lehmann, H.; Rahbar, Samuel; Tuchinda, S; Eng, Lie Injo Luan

doi:10.1111/j.1365-2141.1970.tb01607.x

Cited by 107 publications

(27 citation statements)

References 12 publications

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“…However, several a variants are present in unusually high proportions, composing 30-50% of the circulating hemoglobin in heterozygotes. Included among these "high expression" variants are Hb J Tongariki (10), J Mexico (11), G Philadelphia, Anantharaj, J Nyanza, G Chinese, J Rovigo, J Cape Town (12), Q Thai (13), and Norfolk (14). Three different The publication costs of this article were defrayed in part by page charge payment.…”

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confidence: 99%

Proportion of hemoglobin G Philadelphia (alpha 268 Asn leads to Lys beta 2) in heterozygotes is determined by alpha-globin gene deletions.

Sancar¹,

Tatsis²,

Cedeno³

et al. 1980

Proc. Natl. Acad. Sci. U.S.A.

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In humans the a-globin genes are duplicated and closely linked. Whereas The number and arrangement of the human a-globin genes has been established by utilizing the techniques of molecular hybridization and restriction endonuclease analysis. In most populations the a loci are duplicated and closely linked on chromosome 16 (1-4), each diploid cell containing four a-globin genes. Deletion of variable numbers of a genes occurs in subjects from several racial groups (2, 5-7) and is associated with a decrease or absence of a-globin synthesis characteristic of the different a-thalassemia syndromes (8). In Chinese and Thai populations, the reduction in a-chain synthesis is generally proportional to the number of genes deleted; individuals with a-thalassemia 2 ("silent carrier"), a-thalassemia 1 (a-thalassemia trait), Hb (15); (ii) interaction with a-thalassemia determinants cis or trans to the variant locus (16); and (iii) heterogeneity in the number of a-globin genes that does not produce an imbalance in globin chain synthesis-i.e., variable gene dosage (9,17,18). Subjects synthesizing 31% or 55% Hb J Mexico appear to fit the first model because these individuals possess four a genes (15) Hb G Philadelphia (a68 Asn-Lys) is the most common a-chain variant and occurs in approximately 1 in 5000 American Blacks (21). Most studies indicate that Hb G heterozygotes synthesize either 33% or 50% of the abnormal chain (17,22), although there is a single report of individuals who synthesize approximately 20% Hb G (18). Genetic studies suggest that in most subjects the aG locus is the only functional a locus on the affected chromosome (16,22,23). Whether inheritance of the aG-bearing chromosome confers a-thalassemia has been the subject of debate. Rieder et al. (23) tTo whom reprint requests should be addressed.

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confidence: 99%

Proportion of hemoglobin G Philadelphia (alpha 268 Asn leads to Lys beta 2) in heterozygotes is determined by alpha-globin gene deletions.

Sancar¹,

Tatsis²,

Cedeno³

et al. 1980

Proc. Natl. Acad. Sci. U.S.A.

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“…It is, therefore, unclear why the replacement of this residue by a glycyl residue would affect the oxygen binding properties of the hemoglobin molecule; the differences that have been observed are small but appear to indicate a slight increase in oxygen affinity. Two other variants have been observed that involve substitutions of the same aspartyl residue; these are Hb-Mahidol also known as Hb-G-Taichung and Hb-GThailand in which the substitution concerns a histidyl residue [ 19,20], and Hb-G-Pest in which the aspartyl residue is replaced by an asparaginyl residue [21]. These two variants do not exhibit significant change in their functional properties.…”

Section: Commentsmentioning

confidence: 99%

Hemoglobin Chapel Hill or α₂^Asp→Glyβ₂

1976

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“…[7], Diagnostic finger-prints of the tryptic digests of the globin chains were prepared and stained with ninhydrin (0.2%> in acetone) and with reagents spe cific for methionine, histidine, arginine, tyrosine and tryptophan [8], Preparative finger-prints (containing the digest from about 3.5 mg of globin each) were stained with 0.02°/o ninhydrin in acetone. Elution of the abnormal peptide in NH^OH and digestion with thermolysin was carried out as described before [9]. For analysis, ab normal peptides were eluted in 6 n HC1, hydrolysed in sealed capillary tubes at 110 °C for 18 h, dried and their amino acid compositions determined on an auto matic amino acid analyser.…”

Section: Methodsmentioning

confidence: 99%