In a study of Malaysians of different racial groups, 1,510 sera (908 from Malays, 371 from Chinese and 231 from Indians) were identified for their protease inhibitor (Pi) types. The gene frequencies for the alleles PiM, PiS and PiX in Malays were, respectively, 0.979, 0.015, and 0.007. In Chinese, the frequencies were 0.981, 0.019 and 0.000, and in Indians they were 0.976, 0.24, and 0.000. It is interesting that the usually rare PiX type is found in appreciable frequency in the Malays. Two different types with unusual behavior and obscure origin were also found.
The Land and Sea Dayaks of Sarawak were surveyed for several erythrocyte enzymes. The gene frequency of 6PGDC in 132 Land Dayaks and 127 Sea Dayaks were 0.045 and 0.047, respectively. The gene frequency of PGM1-1 IN 285 Land Dayks and 240 Sea Dayaks were 0.716 and 0.779, respectively. The ADA2 gene frequency in 283 Land Dayaks and 188 Sea Dayaks were 0.154 and 0.090. ADA 5-1 was found once in the Land Dayaks and once in the Sea Dayaks. AK 2-1 was found once in 221 Sea Dayaks but not in any of 270 Land Dayaks. No PHI, LDH or CA variants were found among the Land or Sea Dayaks.
DNA from healthy Malaysian newborns was studied on gene maps after digestion with different restriction endonucleases. Of 65 newborns, two were found to be carriers of two different variants of triplicated alpha-globin loci. In variant no. 1, found in an Malay, the three alpha-globin genes are in an elongated DNA fragment on digestion with Eco RI and Bam HI. The third alpha-globin gene was found in a additional 3.7-kb fragment on digestion with Hpa I, Bgl II and Hind III. In variant no. 2, a new type of triplicated alpha-globin loci, found in a Chinese, the three alpha-globin genes reside in an elongated DNA fragment longer than that of variant no. 1 on digestion with Eco RI and Bam HI. The third alpha-globin gene was found in an additional 4.2-kb fragment on digestion with Hpa I and Hind III. Digestion of this variant DNA with Bg1 II produced an abnormal 16.7-kb fragment in addition to the normal 7.0-kb Bgl-II fragment. The locations of the restriction sites in the two types of triplicated alpha-globin loci are compatible with a mechanism of unequal crossing over following two different modes of misalignment.
Hereditary ovalocytosis/elliptocytosis occurs in polymorphic frequencies among several Malaysian populations and also in Melanesia. Although the condition has been described as an autosomal dominant, Melanesian family studies suggest that it is inherited recessively. Based on 75 Orang Asli families, it is shown that the Malaysian form of elliptocytosis is most likely inherited as an autosomal dominant. It appears, therefore, that either the inference of recessive inheritance in Melanesians is incorrect or that the ovalocytosis/elliptocytosis phenotypes are due to distinct genetic entities in the two regions.
The Indian rubber estate workers in Negri Sembilan, Malaysia, who originated from Orissa in India were found to have a high frequency of Hb S (Joishy SK, Hassan K: Clin Res 28:280, 1980). Unlike the usually severe clinical picture of sickle cell anemia seen in African and American blacks, the clinical picture of the disease in this population was mild and many have reached old age. We studied the leukocyte DNA of 12 patients with sickle cell anemia, ranging in age from 4 to 61 years and 30 sickle cell trait carriers, ranging in age from 7 to 63 years, for the presence of alpha-globin gene deletions by gene mapping according to Southern (Southern EM: J Mol Biol 98:503, 1975), using alpha- and zeta-globin gene probes obtained by nick translation of the alpha- and zeta-globin genes cloned into plasmid. All 12 sickle cell anemia patients were found to have alpha-thalassemia2 (alpha-thal2), either in the homozygous or heterozygous condition. Of the Hb S trait carriers, six did not have alpha-thal2 or alpha-thal1 and 24 had alpha-thal2 (15 heterozygous, 9 homozygous). Seven of these Hb S trait carriers with alpha-thal2 had an additional gene abnormality. Five of them had a fast-moving Eco RI fragment 5.6 kb long that hybridized with zeta-specific probe but not with alpha-specific probe. An unusual DNA pattern of a different type was further found in the other two. Bgl II restriction analysis showed that the alpha-thal2 was mostly of the rightward deletion alpha-thal1 genotype. None of the sickle cell anemia patients and Hb S trait carriers had deletion type alpha-thal1. The sickle cell anemia patients had very high levels of Hb F and low levels of Hb A2. The Hb S trait carriers with alpha-thal2 had relatively low levels of Hb S.
A high frequency of nonhemolytic hereditary ovalocytosis in Malayan aborigines is thought to result from reduced susceptibility of affected individuals to malaria. Indeed, Kidson et al. recently showed that ovalocytes from Melanesians in Papua New Guinea are resistant to infection in culture by the malarial parasite Plasmodium falciparum. In order to determine if protection against parasitic invasion in these ovalocytes might be the result of some altered membrane material property in these unusual cells, we measured their membrane and cellular deformability characteristics using an ektacytometer . Ovalocytic red cells were found to be much less deformable in comparison to normal discoid red cells. Similar measurements on isolated membrane preparations revealed a marked reduction in ovalocytic membrane deformability. To produce equal deformation of ovalocytic and normal membranes, ovalocytes required an 8-10-fold increase in applied shear stress, indicating that their membrane was capable of deforming under sufficient stress. To test the possibility that this increased membrane rigidity might confer resistance to parasitic invasion, we performed an in vitro invasion assay using Plasmodium falciparum merozoites and Malayan ovalocytes of varying deformability from seven different donors. The level of infection of the ovalocytes ranged from 1% to 35% of that in control cells, and the extent of inhibition appeared to be closely related to the reduction in membrane deformability. Moreover, we were able to induce similar resistance to parasitic invasion in nonovalocytic normal red cells by increasing their membrane rigidity with graded exposure to a protein crosslinking agent. Our findings suggest that resistance to parasite invasion of Malayan ovalocytes is the result of a genetic mutation that causes increased membrane rigidity.
A study was carried out of 332 babies suffering from severe neonatal jaundice who were admitted to the General Hospital, Kuala Lumpar, Malaysia. Of the 332 neonates, 51 were premature and 281 were full-term babies, 178 (110 Chinese, 58 Malay, 9 Indian and 1 European-Pakistani) had bilirubin levels of 20 mg% or higher, requiring exchange blood transfusion. Of the Chinese neonates, 23 (20.9%) had G6PD deficiency, 9 (8.2%) had Hb Bart's and 2 (1.8%) had an abnormal haemoglobin, one Hb Q and one fetal variant. Among the Malay infants, 10 (17.2%) had G6PD deficiency, 7 (12.1%) had Hb Bart's and 10 (17.2%) had abnormal haemoglobins (four had Hb E trait, one had Hb K and Bart's in addition to Hb E, three had Hb CoSp with Hb Bart's, one had Hb Q and one Hb Tak). One of the nine Indian neonates had G6PD deficiency and one had Hb S trait. The one European-Pakistani baby was a carrier of Hb D Punjab. In addition to G6PD deficiency, abnormal haemoglobins seem to have contributed to the high incidence of severe neonatal jaundice in Malaysia. The mean activities of GP, GR and GR after stimulation with FAD were higher, while the mean activity of PK and mean level of reduced glutathione were lower than in normal cord bloods. The percent increase of GR after FAD stimulation was significantly lower; fewer in this group had increases above 20% than in normal cord blood. The possible significance of the findings is discussed.
The level of serum alpha-fetoprotein (AFP) was estimated by radioimmunoassay in 153 normal healthy Malysians of different ethnic groups. The mean level was 7.5 In1/ml (SD 2.28InU/ml). Among 330 patients with malignant tumors, 11 had increased levels of AFP. The only patient who had hepatoma had a very high level of serum AFP. High levels were also found in three of four patients with dysgerminoma of the ovary, in the only two patients with carcinoma of the testis, and in one patient with secondary carcinoma of the humerus of unknown origin. Lower, but significantly increased levels were observed in one patient (of 48) with breast carcinoma, one patient (of 8) with basal cell carcinoma of the nose, one patient (0f 27) with carcinoma of the lung, and one patient (of 59) with nasopharynegeal carcinoma.
Hepatitis B virus (HBV) DNA in the serum of 31 patients with histologically confirmed primary hepatocellular carcinoma (PHC) from Malaysia and Indonesia was quantitated by densitometric scanning of autoradiograms obtained by Southern blot DNA hybridization, after electrophoresis using a 32P DNA cloned into plasmid pBR325 as a probe. This quantitation after electrophoresis is more informative than the usual spot hybridization technique. Five of the 31 sera were positive for HBV DNA. Levels ranged between 1.36 pq and 143.18 pq per ml of serum, and the levels of HBsAg, anti-HBs, anti-HBc, HBeAg and anti-HBe in the serum were serologically determined. All five sera positive for HBV DNA were also positive for HBsAg. Three of the five positive for HBV DNA were positive for HBeAg and negative for anti-HBe. Two of the sera positive for HBV DNA were negative for HBeAg but positive for anti-HBe. All sera negative for HBV DNA were also negative for HBeAg. Many sera which were negative for HBV DNA and HBeAg were positive for HBsAg. Of the 31 sera from PHC patients, 23 had at least one HBV marker positive (74.2%).
The combination of Hb E,alpha-thalassaemia and Hb CoSp was found in a 20-year-old female Malay who presented with a moderately severe haemolytic anaemia. The findings in the patient and her family from which this diagnosis was arrived at are discussed. Although this is the first report of this condition in this country it is pointed out that one may see more such cases in the future if one is aware of this condition since Hb E, alpha-thalassaemia and Hb CoSp all occur at significant frequencies in this country.
A study of 23 patients with Hb H disease and their 82 relatives in 17 families showed that 2 types of this condition exist. One is associated with the presence of a small slow-moving component, which we tentatively called the X component and which was invariably present in one parent. Some siblings also had it. The other type was not associated with this component. Two patients without X component had a newborn with Bart’s haemoglobin without X component. None of the parents of 20 newborns with Hb Bart’s without the X component had the X component. It was present in only one parent of each of 2 newborns with Hb Bart’s and the X component. They are thought to represent Hb H disease in the newborn period. We suggest that at least 3 abnormal genes may lead to Hb H disease, which results when 2 of the 3 combine. Severity of clinical and haematological symptoms depends upon which abnormal gene is present and which 2 are involved in any particular combination.
Key Words: a-Thalassaemia; Haemoglobin Bart’s; Haemoglobin H disease; Haemoglobinopathies