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Despite major advances in our understanding of the molecular pathology, pathophysiology, and control and management of the inherited disorders of haemoglobin, thousands of infants and children with these diseases are dying through lack of appropriate medical care. This problem will undoubtedly increase over the next 20 years because, as the result of a reduction in childhood mortality due to infection and malnutrition, more babies with haemoglobin disorders will survive to present for treatment. Although WHO and various voluntary agencies have tried to disseminate information about these diseases, they are rarely mentioned as being sufficiently important to be included in setting health care priorities for the future. It takes considerable time to establish expertise in developing programmes for the control and management of these conditions, and the lessons learned in developed countries will need to be transmitted to those countries in which they occur at a high frequency.

In the South West Pacific region, the striking geographical correlation between the frequency of [[Alpha].sup.+]-thalassemia and the endemicity of Plasmodium falciparum suggests that this hemoglobinopathy provides a selective advantage against malaria. In Vanuatu, paradoxically, [[Alpha].sup.+]-thalassemia increases the incidence of contracting mild malaria in the first 2 years of life, but severe disease was too uncommon to assess adequately. Therefore, we undertook a prospective case-control study of children with severe malaria on the north coast of Papua New Guinea, where malaria transmission is intense and [[Alpha].sup.+]-thalassemia affects more than 90% of the population. Compared with normal children, the risk of having severe malaria was 0.40 (95% confidence interval 0.22-0.74) in [[Alpha].sup.+]-thalassemia homozygotes and 0.66 (0.37-1.20) in heterozygotes. Unexpectedly, the risk of hospital admission with infections other than malaria also was reduced to a similar degree in homozygous (0.36; 95% confidence interval 0.22-0.60) and heterozygous (0.63; 0.38-1.07) children. This clinical study demonstrates that a malaria resistance gene protects against disease caused by infections other than malaria. The mechanism of the remarkable protective effect of [[Alpha].sup.+]-thalassemia against severe childhood disease remains unclear but must encompass the clear interaction between this hemoglobinopathy and both malarial and nonmalarial infections.

An epidemiological study of children on the island of Espiritu Santo in Vanuatu revealed a higher incidence of malaria in alpha-thalassaemic children, an effect most pronounced in the youngest children and for the less virulent malarial parasite Plasmodium vivax. The increased malaria incidence among alpha-thalassaemic children may be due to their beneficial ability to increase susceptibility to P. vivax, which acts as a natural vaccine and generates increased immunity, thus reducing the likelihood of a fatal or life-threatening attack.

The haplotypes of the [Alpha]-globin gene cluster were determined for 99 Indians from the Brazilian Amazon region who belong to 5 tribes: Wayampi, Wayana-Apalai, Kayapo, Arara, and Yanomami. Three predominant haplotypes were identified: Ia (present in 38.9% of chromosomes), IIIa (25.8%), and IIe (22.1%). The only [Alpha]-globin gene rearrangement detected was [[Alpha][Alpha][Alpha].sub.3.7] I gene triplication associated with haplotype IIIa, found in high frequencies (5.6% and 10.6%) in two tribes and absent in the others. [Alpha]-Globin gene deletions that cause [Alpha]-thalassemia were not seen, supporting the argument that malaria was absent in these populations until recently. The heterogeneous distribution of [Alpha]-globin gene haplotypes and rearrangements among the different tribes differs markedly from the homogeneous distribution of Β-globin gene cluster haplotypes and reflects the action of various genetic mechanisms (genetic drift, founder effect, consanguinity) on small isolated population groups with a complicated history of divergence-fusion events. The [Alpha]-globin gene haplotype distribution has some similarities to distributions observed in Southeast Asian and Pacific Island populations, indicating that these populations have considerable genetic affinities. However, the absence of several features of the [Alpha]-globin gene cluster that are consistently present among the Pacific Islanders suggests that the similarity of haplotypes between Brazilian Indians and people from Polynesia, Micronesia, and Melanesia is more likely the result of ancient common ancestry rather than the consequence of recent direct genetic contribution through immigration., Adult hemoglobin (HbA) is the predominant hemoglobin in human blood in adult life in addition to small amounts of fetal hemoglobin (HbF) and hemoglobin [A.sub.2]. HbA consists of two pairs [...]

An analysis of 36 Melanesians provided an insight into allelic sequence polymorphism at the beta-globin locus. Haplotype associations are evident in connected polymorphisms. Recombination and gene conversion may be responsible for the haplotype diversity. An average age of sequence divergence of around 450,000 years is evident.

A computer simulation model proposed for the genesis of a locus of variable numbers of tandern repeats (VNTRs) facilitated the analyses of additional rates as well as distinct constraints of recombination. The analyses, confined to population genetics of VNTRs, hypothesize the neutrality of VNTRs and the initial evanescence of VNTR polymorphism. The validation of the intrinsically poor fit to the infinite alleles models of simulated VNTR variations and estimated VNTR polymorphism derivatives of two Papua New Guinean populations.

An experiment to crystallize alpha-Si:H samples into polysilicon via excimer-laser annealing is presented. The resulting material, which consists of a large-grain surface with a fine-grain layer beneath, is used to fabricate thin film transistors with high field-effect mobility. Transmission electron microscopic analysis and surface reflectance measurementsprovide an electrical and material characterization of the crystallized samples.

A model describing the evolutionary persistence of single tandemly repetitive DNA (TR-DNA) is analyzed. The study assumes that variable numbers of tandem repeats (VNTRs) can be grouped with satellite DNAs to create a class of TR-DNA. The evolutionary process is likewise assumed to flow from an unbiased recombinational process. Results show that misalignment constraint generates VNTR loci evolution including minisatellites. The results support nonrandom VNTR and other TR-DNA distributions in the human genome.

Analysis of mitochondrial DNA from ancient human bones found on Easter Island near Chile revealed that Easter Islanders were of Polynesian origin. The bones were excavated from two archaeological sites situated on opposite ends of the island.