Alpha-1-protease inhibitor in bronchial asthma: phenotypes and biochemical characteristics

The prevalence of the different phenotypes of alpha 1-protease inhibitor (alpha 1PI) was investigated in a group of 90 asthmatic patients and compared with that of a control group of 240 individuals representing the general population. The M2M2 phenotype occurred more frequently in the asthmatic group (p = 0.015). Plasma samples of 51 of the asthmatic patients randomly selected from the different phenotype groups identified were studied for the absolute plasma values of alpha 1-PI and the inhibitory capacity of plasma for porcine pancreatic elastase, and compared with those from 21 nonasthmatic individuals of the M1M1 phenotype. Although the asthmatic patients had higher absolute alpha 1PI values (p = 0.04), the plasma elastase inhibitory capacity was markedly reduced compared with the nonasthmatic subjects (p = 0.01). The functional efficiency of alpha 1PI from asthmatic patients of the M1M1, M1M2, and M2M2 phenotypes was significantly decreased compared with that of the nonasthmatic M1M1 individuals. Functional deficiency of alpha 1PI may be important in the pathogenesis of the inflammatory process that characterizes bronchial asthma.

The Y-associated XY275 low allele is not restricted to indigenous African peoples

The level of linkage disequilibrium between the XY275 MspI polymorphism and the X and Y boundaries was investigated in 21 different southern African populations. A full range of frequencies of the high allele was observed on the 1,013 X chromosomes studied, in keeping with published data. In previous studies fixation of the high allele on the Y chromosome was observed in all but two groups--a Pygmy and a Tsumkwe San population. However, in the present study of 673 Y chromosomes, the low allele was found to be associated with the Y chromosome in several different Bantu-speaking negroid groups, the Khoisan-speaking negroid Dama, the Khoisan, two groups of mixed ancestry, and the South African Asiatic-Indian population. The discovery of the low allele on Y chromosomes of caucasoid individuals suggests that more than one class of Y chromosome gave rise to the present-day non-African population. The data also fail to provide support for the theory that Africa is the site of origin of Homo sapiens, but they equally do not exclude it.

The Y chromosome as a tool for studying human evolution

The use of the Y chromosome in human evolutionary research has only recently begun to gain momentum, partly because of a paucity of polymorphism. Differences in male/female behaviour patterns and the unique mode of inheritance of the Y chromosome also complicate interpretation of the data on Y chromosome variation.

Y chromosome probe p49a detects complex PvuII haplotypes and many new TaqI haplotypes in southern African populations

Y-specific 49a/TaqI haplotypes were determined for 831 individuals drawn from 21 different southern African populations. A total of 31 new haplotypes were observed, some of which contained new alleles or allelic variants. Duplication, in addition to CpG mutation, is implicated in the generation of certain allelic variants. Cluster analysis of genetic distances between the populations, calculated using the 49a/TaqI haplotype frequencies, revealed a basic split between African and non-African populations. Hybrid groups cluster with the caucasoid groups, indicating that male gene flow has occurred from the latter into the former. Clustering of the negroid and Khoisan groups is not what might have been expected from the known linguistic affinities. It is suggested that the 49a/TaqI haplotype analysis of these populations is not sufficiently sensitive to distinguish between many of the populations. The Y-specific 49a/PvuII polymorphism was studied in 127 individuals from southern African populations, and 17 polymorphic fragments ranging in size from 3.6 kb to greater than 48 kb were identified. A total of 53 PvuII haplotypes were observed, corresponding to only 30 TaqI haplotypes. There appears to be poor correlation between the two polymorphisms.

The inverted Y-chromosome polymorphism in the Gujarati Muslim Indian population of South Africa has a single origin

Y-specific polymorphisms were studied in Gujarati Muslim Indians possessing a Y-chromosome pericentric inversion [inv(Y)] in an attempt to prove a common genetic origin for the inversion. The p49a/TaqI and p49a/PvuII haplotypes were determined for 9 normal and 8 inv(Y) Gujarati Muslim men. Men with the inversion possessed identical TaqI and PvuII profiles, as opposed to 7 different TaqI and 8 different PvuII haplotypes observed in the 9 normal men. These results provide conclusive evidence for a common genetic origin of the inverted Y chromosome observed in this Gujarati Muslim community.

The structure of human mitochondrial DNA variation

Restriction analysis of mitochondrial DNA (mtDNA) of 3065 humans from 62 geographic samples identified 149 haplotypes and 81 polymorphic sites. These data were used to test several aspects of the evolutionary past of the human species. A dendrogram depicting the genetic relatedness of all haplotypes shows that the native African populations have the greatest diversity and, consistent with evidence from a variety of sources, suggests an African origin for our species. The data also indicate that two individuals drawn at random from the entire sample will differ at approximately 0.4% of their mtDNA nucleotide sites, which is somewhat higher than previous estimates. Human mtDNA also exhibits more interpopulation heterogeneity (GST = 0.351 +/- 0.025) than does nuclear DNA (GST = 0.12). Moreover, the virtual absence of intermediate levels of linkage disequilibrium between pairs of sites is consistent with the absence of genetic recombination and places constraints on the rate of mutation. Tests of the selective neutrality of mtDNA variation, including the Ewens-Watterson and Tajima tests, indicate a departure in the direction consistent with purifying selection, but this departure is more likely due to the rapid growth of the human population and the geographic heterogeneity of the variation. The lack of a good fit to neutrality poses problems for the estimation of times of coalescence from human mtDNA data.

A third TaqI allele is detected by the probe pTD3-21 (D15S10) in southern African chromosomes

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Utility of Leopold maneuvers in screening for malpresentation

Malpresentation is a common complication of pregnancy. Using ultrasound as the gold standard, we prospectively tested Leopold maneuvers as a screen for nonvertex presentation in the third trimester. In our hands this technique performed poorly. Values for sensitivity, specificity, positive predictive value, and negative predictive value were 28, 94, 24, and 95%, respectively, in a population with a 7% prevalence of noncephalic presentation. Much of the correlation between the screening and diagnostic tests seemed to arise from chance (kappa = 0.13).

Study of 30 DNA markers in three southern African populations

Thirty anonymous DNA markers were investigated in Southern African Caucasoid, Negroid and San populations. Sixteen of these are new markers that were developed in our laboratory; the remainder are closely linked to the cystic fibrosis locus on chromosome 7. Average heterozygosity in the Caucasoid and Negroid populations was calculated at the loci identified by each of the anonymous probes, using two approaches, and was found to be .0020 and .0030 for the Caucasoid population and .0023 and .0025 for the Negroid population. Variation between populations (measured by FST) and between markers was calculated from allele frequency data gathered for all markers in the three populations. Significant differences in allele frequency between the populations were observed for the cystic fibrosis markers MET D, MET H and 7C22, with little or no variation observed in the Negroid and San populations. Mean heterozygosity (D) was found to be considerably lower in San (.250) than in Caucasoid (.373) and Negroid populations (.0320) and possible explanations for this are provided. The smallest genetic distance (60 x 10(-3)) was found between the Negroid and San populations, and the greatest distance between the Caucasoid and San populations (167 x 10(-3)).

Catecholamine levels in pregnant physicians and nurses: a pilot study of stress and pregnancy

As a pilot study of occupational stress and pregnancy, we measured urinary catecholamine excretion in ten pregnant physicians and three intensive care nurses between 26-37 weeks' gestation, once during a work day and again during a non-work day. Urinary catecholamines were increased by 58% (P less than .03) during work periods compared with non-work periods. Catecholamine levels were also increased by 64% (P less than .025) over those of a working non-physician control group of similar gestational age. Urinary catecholamine levels are a direct reflection of plasma catecholamine levels. Catecholamine levels are known to increase with physical stress, such as standing, and with mental stress, such as difficult problem-solving. Catecholamines are also known to decrease uterine blood flow. Measurement of catecholamines may be a helpful marker in investigating the relationship between occupation and pregnancy outcome.

Prenatal diagnosis for Huntington's disease: a molecular and psychological study

Two linked probes were used to determine the Huntington's disease status of the fetus conceived by a woman affected with the condition. The fetus was found to be unaffected with a certainty of 97 per cent. The ethical issues associated with presymptomatic testing were avoided since the mother presented with initial symptoms of Huntington's disease, but other psychological and ethical issues arose. The concerns of an affected woman planning a pregnancy, and the dilemmas involved in decision-making regarding prenatal diagnosis and possible selective abortion were exposed and explored with the patient and her husband.

A two allele XbaI RFLP at the catalase 2 locus

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In quest of the tyrosinase-positive oculocutaneous albinism gene

The gene which causes tyrosinase-positive oculocutaneous albinism (ty-pos OCA) is not known. Forty-seven Bantu-speaking Negroid families with ty-pos OCA were studied in an attempt to find linkage to the gene. Fifteen 'classical' and seven DNA polymorphisms were used in the search for linkage. Close linkage was excluded for the Rh, Gc and beta-globin loci. There is no suggestion of linkage to MNS, ABO, PGM1, 6PGD, ACP1, GPX1, GLO1, GPT1, PEP A, Tf, alpha 1-AT, Hp, DQA, DXA and three arbitrary restriction fragment length polymorphisms (RFLPs). There is a slightly positive lod score for pAW101 (D14S1) (0.591 for theta = 0.2). An 'interesting' lod score was obtained with Bf and a haplotype generated by the markers DQA and DXA (1.575 for theta = 0.1 and 0.979 for theta = 0.2, respectively). Further testing of markers on chromosome 6p are indicated. Although ty-pos OCA in Southern Africa is likely to be a homogeneous disorder, genetic heterogeneity cannot be excluded as differences due to the presence/absence of ephelides within families have been observed. To date 57% of the genome has been excluded from linkage with ty-pos OCA.

Red or rufous albinism in southern Africa

Red or rufous albinism is a rare type of oculocutaneous albinism described, but not as yet fully investigated, in Africa and New Guinea. Twelve rufous albino subjects from 10 families participated in this preliminary study. The prevalence of rufous albinism was found to be approximately one in 8,580 among school children in the negroid population. The combination of the unusual red skin colour, ginger to reddish hair colour, low susceptibility to sun damage, and minimal visual problems, in affected individuals, suggested that they form a group which is distinct from the brown and other types of albinism. The mode of inheritance was found to be recessive. Tyrosinase assays showed that rufous albinos are tyrosinase positive and on electron microscopy studies normal melanosomes and melanocytes were observed in hair bulbs and skin. Visual evoked potential testing did not show the gross decussation abnormalities of the optic pathway detected in other types of albinism. Rufous albinism might be at one end of the spectrum of types of oculocutaneous albinism and, because affected people have such mild symptoms, their inclusion in this group might be debatable.

pDP1007, detects an X polymorphism with HindIII in negroids at the ZFX locus

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Phenotypic expression of the HLA linked iron-loading gene in males over the age of 40 years: a population study using serial serum ferritin estimations

The frequency of the HLA linked iron-loading gene was assessed in 1783 Afrikaner men over the age of 40 years living in the South Western Cape. Measurements, made on three occasions over a 4.5 year period, included the serum ferritin concentration, a screening test for reduced unsaturated iron-binding capacity and the percentage transferrin saturation. The serum gamma-glutamyl transferase concentration was used as a marker of alcohol abuse. The diagnosis of homozygosity was based on a serum ferritin concentration that was persistently greater than 400 micrograms l-1 and a percentage transferrin saturation greater than 55%. Using these criteria, 17 subjects were diagnosed as homozygous, corresponding to a disease frequency of 0.0095, a gene frequency of 0.0976 and a heterozygote frequency of 0.176 (95% confidence limits: 0.135-0.213). None of the subjects had overt clinical haemochromatosis. Typing for the HLA-A, -B, -C and -DR loci showed that the HLA-A3 allele (frequency 0.6471 and relative risk 4.4) was the only independent marker for the iron-loading gene in this asymptomatic population. Using the present approach it was not possible to distinguish between heterozygotes, alcohol abusers and normal subjects with serum ferritin concentrations at the upper end of the normal range.

New TaqI allele detected by X-chromosome probe s21 (DXS17)

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Prevalence of familial hypercholesterolemia in Johannesburg Jews

The prevalence of heterozygous familial hypercholesterolemia was determined in a representative sample of 403 young Jewish men resident in Johannesburg, South Africa. Preliminary screening by measurement of serum total cholesterol demonstrated that 25 of them had levels greater than or equal to 7.5 mmol/l (290 mg/dl). On the basis of subsequent clinical, biochemical, and family studies, 6 men, or about 1 in 67 of the total sample, were considered to be heterozygotes. This very high prevalence, about 7 times greater than that found in other Caucasian populations, is probably related to founder effect. It may help to explain the high frequency of coronary heart disease in Johannesburg Jews.

A decade of mid-trimester amniocentesis in Johannesburg. Prenatal diagnosis, problems and counselling

Selected data from 4,554 cases of amniocentesis performed in Johannesburg over a decade are presented. The demand for the service increased fivefold over the 10 years. The indications were: chromosome defects (83%), neural tube defects (11%), other disorders (4%) and parental anxiety (2%). A correct prenatal diagnosis was made in 99.9% of cases and sexing was correct in 99.6% of cases. Abnormalities were detected in 3.2% of pregnancies. The rate of 'spontaneous' abortion within 1 week after amniocentesis was 0.7%, and the total 16-28-week fetal loss rate is not much increased over the risk for such an event in any second-trimester pregnancy. The procedure has become a safe and a successful one in expert hands.