Newborns were examined for the presence of slow-moving haemoglobin components, tentatively designated X components and previously found in a group of Hb H disease in which invariably one of the parents of each patient had the same slow-moving Hb X components also. Structural studies showed that the abnormal haemoglobin in Chinese was identical with Hb Constant Spring, an c-chain variant. Newborns with Hb Bart’s and slow-moving X components invariably had one parent with the X components also. When the child grew older Hb Bart’s disappeared while the Hb X components remained in the blood. The homozygous state for the X components was found in a Malay boy through his newborn brother who had the X components in addition to Hb Bart’s and had both parents with the X components. One other Malay baby had the X components and Hb A2 Indonesia inherited from the parents. The present study of newborns also showed that Hb Bart’s can accompany different abnormalities of haemoglobin production, involving alpha-chains, beta-chains as well as gamm-chains. Its presence in cord blood is, therefore, not specific for alpha-thalassaemia
Key Words: Haemoglobinopathies; Hb Bart’s; Slow-moving Hb X; Thalassaemia
Blood samples, demographic and cultural data were collected from seven settlements of Semai Senoi, a swidden farming ethnic group of Malaysia. Three genetic loci (ABO blood group, hereditary ovalcytosis, and hemoglobin) were analyzed in a total sample of 546 individuals. These data indicate a considerable degree of genetic microdifferentiation in this area of the Semai distribution. Parent-offspring birthplace data (analyzed by means of a migration matrix) and settlement histories show that settlements are not strongly isolated. Genetic differences in the study area demonstrate a reasonable correspondence with migration and the history of the settlements. Genetic convergence also occurs through the addition of migrant groups to established populations leading to new patterns of marriage between donor and recipient groups. The genetic structure of the total Semai population through time thus comprises a mosaic of shifiting allele frequencies in a series of semi-isolated local populations.
Analysis of histories and genealogies from seven relatively unacculturated, swidden-farming Semai settlements shows that the composition of local groups fluctuates through time. This instability is similar to a pattern which Neel and his colleagues have suggested is typical of primitive society, the fission-fusion model. In addition, the individuals comprising Semai fission groups are kinsmen which implies that the number of independent genomes represented is markedly less than the number of individual migrants (the lineal effect). Fission groups may form new villages or fuse with an established settlement. In either case, the genetic effects of such migration are more pronounced than would be expected on the basis of founder effect or random migration. Despite several conspicuous differences in social organization between the Semai and the South American Indians (e.g., bilateral vs. unilineal descent) whose population structure provided the empirical basis for the fission-fusion, lineal effect model, the basic similarities are striking. The Semai case thus lends support to the proposition that this pattern may be of some generality in technologically primitive populations.
The Land Dayaks and the Sea Kayaks of Sarawak were surveyed for haptoglobin, transferrin and serum albumin variants. The Hp1 gene frequency was 0.385 in 283 Land Dayaks as well as in 205 Sea Kayaks. The TfDChi gene frequency in 283 Land Dayaks was 0.030 and in 188 Sea Kayaks it was 0.040. Serum albumin Medan was found in one of the 188 Sea Kayaks.
All subspecies of black rats (Rattus rattus) used in the present study are characterized by having large and clear C-bands at the centromeric region. The appearance of the bands, however, is different in the subspecies. Chromosome pair No. 1 in Asian type black rats (2n=42), which are characterized by an acrocentric and subtelocentric polymorphism, showed C-band polymorphism. In Phillipine rats (R. rattus mindanensis) the pair was subtelocentric with C-bands, but in Malayan black rats (R. rattus diardii) it was usually acrocentric with C-bands. In Hong-Kong (R. rattus flavipectus) and Japanese black rats (R. rattus tanezumi) it was polymorphic with respect to the presence of acrocentrics with C-bands or subtelocentrics without C-bands. The other chromosomes pairs showed clear C-bands, but in Hong-Kong black rats the pairs No. 2 and 5 were polymorphic with and without C-bands. In Japanese black rats, 6 chromosome pairs (No. 3, 4, 7, 9, 11 and 13) were polymorphic in regard to presence and absence of C-bands, but the other 5 chromosome pairs (No. 2, 5, 6, 8 and 10) showed always absence of C-bands. Only pair No. 12 usually showed C-bands. C-bands in small metacentric pairs (No. 14 to 20) in Asian type black rats generally large in size, but those in the Oceanian (2n=38) and Ceylon type black rats (2n=40) were small. In the hybrids between Asian and Oceanian type rats, heteromorphic C-bands, one large and the other small, were observed. Based on the consideration of karyotype evolution in the black rats, the C-band is suggested to have a tendency toward the diminution as far as the related species are concerned.
Hidrotic ectodermaldysplasia was found, to our knowledge, for the first time in a Chinese family in Malaysia, and it affected 15 members in five generations. The disease, which is transmitted as a non-sex-linked autosomal dominant trait, presumably originated from southern China. All 15 members had the typical nail, hair, and skin lesions, and we observed three different types of nail defects. Scalp alopeica was more extensive in the female members while keratoderma of the palms and soles was more notable in the male members. The nail and skin lesions also became severer with age. Except for the infectious eczematoid dermatitis present in the propositus, none had other skin or systemic disorders. All were relatively healthy and had normal life expectancies;
It has been reported that studies of the genetic consequences of inbreeding should adopt a different strategy in populations having a relatively old inbreeding history and where inbreeding levels have varied over time. This contention is tested with a series of 39,495 single-birth records from Bombay, India, collected in a World Health Organization survey on congenital malformations. Our analysis reveals that: 1. the incidence of major malformations is significantly higher among the inbred offspring (1.34%) as compared to that among non-inbred ones (0,81%)--a finding at variance with a previous study in the same area; 2. the inbreeding effect on perinatal mortality (stillbirths and mortality during the first few days of life) is also found to be significant. In view of the above findings, the genetic load as disclosed by inbreeding is computed for perinatal mortality, major malformations and pooling these together. A + B, the measure of the number of lethal equivalents per gamete, is found to be at variance with other reports. Such variability can be ascribed to non-genetic factors. Supporting evidence collected from Brazil and Malaysia in the same survey is also presented.
alpha1-Antitrypsin types were determined in 200 individual specimens of Malaysian Macaca irus. We found the pattern B in 76 samples, BC in 116, and C in 8. Assuming that these patterns are determined by codominant alleles at one locus, this distribution constitutes a significant (P less than 0.001) deviation from Hardy-Weinberg equilibrium, because of an excess of BC and low prevalence of C. We found no clear evidence for the presence of alpha1-antitrypsin deficiency comparable to the situation in man.
Histocompatibility locus A typing of 43 Malaysian Chinese and 51 Hong Kong Chinese patients with nasopharyngeal carcinoma (NPC) confirmed the association between the occurrence of A2-Sin 2 and the increased risk for NPC that was previously demonstrated in Singapore Chinese. The results support the previous interpretation that the histocompatibility locus A genotype of importance in NPC predisposition is the A2-Sin 2 haplotype. The histocompatibility locus A-linked, genetically determined NPC risk is common to Asian Chinese from at least three geographic locations.