Genetic studies among seven endogamous populations of the Koshi Zone, Bihar (India)

The distribution of AB0 and Rhesus blood groups, PTC taste sensitivity and colour blindness was studied among seven endogamous populations (Tharu, Mushar, Santal, Dhobi, Julaha, Kulhaiya and Karan Kayastha) in the Koshi Zone of Bihar (India). The phenotype and allele frequencies of the four gene loci (AB0, RH, PTC and colour blindness) show considerable differences between these populations. The measurement of genetic distances revealed, that the lowest genetic distance is seen between Dhobi and Julaha, the highest between Mushar and Tharu. From the genetic distance analysis there is some evidence for a close genetic relationship among the population groups belonging to the same region, irrespective of their caste, religion, linguistic or any other affinities. It may be concluded that all these populations have arisen through a common ancestor and changed gene frequencies among them is due to evolutionary forces like mutation, selection, migration, temporal variation and genetic drift. However, these populations retain their separate entities by practising endogamy. Gene diversity analysis reveals that these populations are at an early stage of genetic differentiation.     

Anthropological studies in Assam, India

Four Assamese caste groups--Jogis, Hiras, Kumars and Kaibartas--have been analysed for the distribution of anthropometric and dermatoglyphic traits as well as for the distribution of ABO blood groups and PTC taste sensitivity. The differences among these four caste groups are statistically mostly significant, which can be connected with the history of these groups and their genetic isolation from each other.     

Genetic polymorphism study at four minisatellite loci (D1S80, D17S5, D19S20, and APOB) among five Indian population groups

The present study reports the genetic variation observed among five anthropologically distinct population groups of India, using four highly polymorphic minisatellite loci (D1S80, D17S5, D19S20, and APOB 3' VNTR) in order to examine the effect of geographical and linguistic affiliations on the genetic affinities among these groups. Random individuals from five ethnic groups were studied; the sample size ranged from 235 to 364. The population groups belong to two geographically separated regions of India, the state of Maharashtra (western India) and the state of Kerala (southern India). The two Maharashtrian groups (Konkanastha Brahmins and Marathas) speak "Marathi," an Indo-European language, whereas the three Kerala population groups (Nairs, Ezhavas, and Muslims) speak "Malayalam," an Indo-Dravidian language. Genomic DNA was extracted from peripheral blood samples and analyzed using amplified fragment length polymorphism (Amp-FLP) technique. All four loci displayed high heterozygosity with average heterozygosity in the range of 0.82 to 0.84. The Polymorphic Information Content and Power of Discrimination were > or = 0.75 and > or = 0.80, respectively. The coefficient of gene differentiation was found to be low (average G(ST) = 1.2%; range between 0.6% at D1S80 locus to 1.6% at APOB 3' VNTR locus) across the loci, indicating close affinity among the population groups. The neighbor-joining tree revealed two clear clusters, one for the two Maharashtrian population groups and the other for the three Kerala population groups. The results obtained are in conformity with the geographical and linguistic backgrounds of the studied populations.     

Genetic heterogeneity of Apo CII locus in north India

Apolipoprotein CII genotypes were determined in Brahmins, Banias, Jat Sikhs, Khatris, Ramgarhia, Ramdasia and Scheduled Castes of Punjab, North India (n = 930). The Apo CII exhibits three common polymorphic alleles CII*1, CII*2 and CII*3 with pooled frequencies 0.883, 0.114 and 0.003, respectively. CII*3 was absent in Brahmins. Distribution of Apo CII isoforms highlights a considerable variation among different ethnic groups across the world. The average heterozygosity of the Punjabi populations was 0.208. The gene diversity among these population groups was less than 0.1%.     

Ability to test phenylthiocarbamide (PTC-test) among the population of Kirghizia]

The distribution of the taste sensitivity to phenylthiocarbamide (PTC) among 320 Kirghiz boys, 320 Kirghiz girls, 45 Russian boys and 200 Russian girls was studied. The measurements of taste sensitivity to PTC was carried out by the standard method with a scale of PTC dilution to 29.     

Molecular genetic diversity in 5 populations of Madhya Pradesh, India

This paper presents data on the distribution of 3 amplified fragment length polymorphisms (D1S80, APOB, and YNZ22) in 5 populations of Central India. Using the polymerase chain reaction technique, 3 caste (Brahmin, Khatri, and Dhimer) and 2 tribal (Gond and Baiga) populations were studied for the 3 loci. The allelic variations observed in the caste populations are compatible with those of many Caucasian populations, but the caste populations showed significant overall and interpopulation variability within the region. D1S80 allele *24 varied from 32% (Dhimers) to 42% (Brahmins). Allele *18 was not observed in Baiga tribal populations, but in caste populations it varied from 11% (Dhimers) to 24% (Brahmins). Both tribal populations showed higher frequencies of allele *31 (17%-18%). For APOB, caste populations again showed bimodal distribution of alleles *35 and *37, but in tribal populations higher allele numbers (*47, *49) were also frequent. For YNZ22, extensive variation was observed for all populations studied. Allele *4 was the most common in caste populations, while alleles *2, *7, and *10 were prominent in tribal populations. The level of gene differentiation is not very high for the 3 systems studied in the 5 populations. Overall, allele frequency distribution, heterozygosity, and genetic diversity analysis show that the genetic diversity observed is socially and geographically structured.     

Anthropological studies in Assam, India. 4. Observations on the Kalitas

Five regional groups of the Kalitas, an Assamese caste group, have been investigated for the distribution of anthropometric and dermatoglyphic traits as well as for the distribution of ABO blood groups and PTC taste sensitivity. The intergroup variability is to some extent considerable. The possible reasons for that are discussed.     

Effect of high altitude on sensitivity to the taste of phenylthiocarbamide

Sensitivity to the taste of phenylthiocarbamide (PTC) was studied using the Harris-Kalmus method in healthy human volunteers at sea level and then subsequently at an altitude of 3500 m over a period of 3 weeks, after which they were brought back to sea level. Blood sugar, insulin and blood cortisol levels were estimated weekly. The results indicated that, out of 51 subjects studied, 26 (55%) were PTC tasters at sea level. Eight of those unable to taste PTC at sea level tested as tasters at high altitude, and 2 of them reverted to being non-tasters on return to sea level. In the blood, an increase in cortisol and blood insulin levels was seen without any significant change in sugar levels. All the changes recorded at high altitude tended to return to basal values after re-induction to sea level. The study suggests that high-altitude hypoxia in some way, possibly involving changes in hormonal profile among other factors, causes an alteration in sensitivity to the taste of PTC, resulting in some of the individuals shifting to lower PTC sensitivity. Received: 24 November 1999 / Accepted: 25 January 2000     

Blood groups among brahmin and kamma caste populations of coastal Andhra Pradesh

Blood specimens from Brahmin and Kamma caste populations of Coastal Andhra Pradesh, India are examined for A₁A₂BO, MNSs, and Rhesus blood groups. Predominance of A group in Brahmins and B group in Kammas is observed. Phenotype A₂ records less than 4% in both populations. High frequencies of genes M, s, D, and e are exhibited among both populations. Statistically significant differences are found only for A₁A₂BO system between Brahmins and Kammas.     

Anthropological studies in Assam, India. 6. Differentiation processes among Assamese populations

In 1978-79 13 Assamese populations--two Muslim groups, five Mongoloid groups and 6 Hindu caste groups--have been investigated for the distribution of anthropometric, anthroposcopic and dermatoglyphic traits as well as for the distribution of ABO blood groups and PTC taste sensitivity. Except for finger ridge patterns all traits under investigation showed a marked intergroup variability. For anthropometric, anthroposcopic and dermatoglyphic traits a clear differentiation in Mongoloid populations on one hand and Hindu caste groups on the other could be observed and be substantiated by results of corresponding distance analyses. With regard to Muslims it has to be distinguished between Marias who seem to be more closely related to Mongoloid populations and Sheikhs whose phenotypic appearance is more like that of the Hindu caste groups. The results are discussed.     

Red cell enzyme polymorphism: Gene differentiation in three populations of Maharashtra,India

Blood samples of 1,266 individuals were collected from three caste populations; Nava Budha (Mahar), Maratha, and a mixed group of Scheduled castes from each of three districts of Maharashtra, Nagpur, Akola, and Thane. The samples were tested for 12 enzyme systems, viz., AcPh, AK, CA-I, CA-II, Est-D, LDH, MDH, Oxidase, PGM-1, PGM-2, 6-PGD, and PHI. The gene frequencies of these loci are within the ranges observed among the Indian populations so far studied. The total differences in gene frequencies for each polymorphic locus was partitioned into three components, i.e., the differences between caste populations, the differences between regions, and the differences due to interaction between caste populations and regions. The results show that besides caste variation for two loci, Est-D and PGM-1, the gene frequencies for AK, Est-D, and G-6PD loci have different geographical distributions.     

Comparing sensory experience in bitter taste perception of phenylthiocarbamide within and between human twins and singletons: intrapair differences in thresholds and genetic variance estimates

BACKGROUND: Quantitative genetic studies revealed that not all of the phenotypic variance in PTC taste perception is heritable. AIM: To study quantitative variations in PTC tasting ability in twins and to estimate heritability of PTC taste perception on the taste of twin data on males and females sexes separately. SUBJECTS AND METHODS: The data for PTC taste sensitivity following the classic method of Harris & Kalmus (1949) were collected on a sample of 141 twin pairs (66 MZ and 75 DZ) and 275 singletons (128 males and 147 females) from Chandigarh, India. Genetic analyses were performed following Christian (1979), Donner (1986) and Sham (1998). RESULTS: Frequency of non-tasters was similar in twins (33 %) and singletons (32 %), but significant sex differences were observed. No differences were found between zygosities for mean thresholds. Similarly, no evidence of variance heterogeneity and environmental covariance was seen between zygosities. Since no basic assumption of the twin method was found violated, within-pair estimates of genetic variance would be unbiased. These estimates were highly significant in both males and females. However, dominance and additive components of genetic variance were found to differ between sexes. CONCLUSION: PTC thresholds do not seem to be significantly affected by environmental factors as no variance inequality was observed between twin zygosities. Intensity of bitterness (scalar dimensions) of PTC is a separate trait having no commonality with the genetic basis of recognition threshold for PTC tasting ability. The receptors recognizing bitter taste are different from the receptors determining intensity of taste. The absolute difference between co-twins in PTC thresholds can be used as a simple tool in the twin zygosity diagnosis. The results show that none of the MZ co-twins had manifested difference of more than 3 in their PTC threshold.     

Age, gender and caste variations in scalp hair micro-morphological variables among Brahmins and Banias of Punjab, India

A cross-sectional sample of 3136 scalp hair drawn from 392 individuals aged 10 to 60 years and belonging to the Bania (n = 201) and Brahmin (n = 191) caste groups of Punjab State of India were examined for diameters of hair shaft and medulla, scale count, medulla type, hair index, medullary index and scale-count index, employing standard procedures. The mean hair shaft diameter, medullary diameter, incidence of medullation and scale-count index was higher in males, while the mean scale count was higher in females. However, with a few exceptions, the gender differences were not statistically significant (p < 0.05). The Brahmins showed significantly (p < 0.05) higher mean values of hair shaft diameter and scale count than the Banias. The mean scale-count index was higher among the Banias. The fragmentary medulla was the most common medullary type among the Banias, while the continuous medulla was the most frequent type of medulla among the Brahmins. The frequency of medullation was significantly more among the Banias. On the average, the hair shaft diameter and diameter of medulla increased up to 30 years. Some age variations in medullation were noticed in both the caste groups. No clear age trend was noticeable in the scale count. By and large, the mean hair shaft diameter of the Banias was less than that of other populations. The mean hair shaft diameter of the Brahmin males was greater than that of the Banias, the Onges, and the Bengalees. The Brahmin females showed greater mean hair shaft diameter than that of the Banias, the Australian Aborigines, the Juangs and the Onges. Human scalp hair shows some age, gender and population variations in micro-morphological variables which have the potential of being useful for anthropological and forensic investigations.     

Genetic Sensitivity to 6-n-Propylthiouracil (PROP) and Hedonic Responses to Bitter and Sweet Tastes

Genetically mediated sensitivity to the bitter taste of 6-n-propylthiouracil(PROP) has been associated with greater acuity for bitter andfor some sweet tastes. Thus far, few studies have explored therelationship between PROP taste sensitivity and hedonic responsesto bitter and sweet. In this study, 87 normal-weight young womenwere divided into PROP non-tasters (n = 18), regular tasters(n = 49), and supertasters (n = 20), based on their PROP detectionthresholds and the scaling of five suprathreshold solutionsof PROP and NaCl. Non-tasters had thresholds >1.8 x 10^–4mol/l PROP. Supertasters had thresholds <3.2 x 10^–5mol/l PROP and PROP/NaCl ratios >1.70. As expected, dislikeof the bitter taste of PROP was determined by its perceivedintensity, which was greater among supertasters than among regulartasters or non-tasters. Significant correlations were observedbetween PROP taste thresholds and the sum of intensity ratings(r = –0.61) and between summed intensity and summed hedonicratings (r = –0.80). PROP taste sensitivity was weaklylinked to enhanced perception of sweet taste, but did not predicthedonic responses to sucrose or to saccharin solutions. Giventhat the dislike of PROP solutions is determined by their perceivedintensity, hedonic responses to PROP solutions may provide arapid way of screening for PROP taster status. Chem. Senses22: 27–37, 1997.     

Microsatellite variation at 24 STR loci in three endogamous groups of Uttar Pradesh,India

We have studied variation at 24 microsatellite markers among 50 individuals from each of three endogamous groups, Bhargavas, Chaturvedis, and non-Bhargava, non-Chaturvedi Brahmins of Uttar Pradesh, India. The number of alleles at the loci tested varied from 4 to 11, with an average of 6 at each locus. Heterozygosity was found to be quite high at all loci in the three subpopulations. It varied between 0.44 to 0.84 among Bhargavas (average 0.6510), 0.44 to 0.80 among Chaturvedis (average 0.6633 +/-), and 0.42 to 0.85 among Brahmins (average 6.694 +/-). Hardy-Weinberg equilibrium analysis revealed that these populations are under genetic equilibrium at almost all the loci tested. Comparisons of allele frequency between Bhargavas and Chaturvedis showed that they differed significantly at 14 short tandem repeat (STR) markers (p < 0.001), while Chaturvedis and Brahmins differed at 6 (p < 0.05) and Brahmins and Bhargavas at 8 (p < 0.05). Average F(IS) and F(ST) for the 24 STR markers was -0.02 and 0.013, respectively. We used both un-weighted pair group with arithmetic mean and principal components analysis to evaluate genetic distances among the three groups. Our results revealed that although there were differences at particular allele frequencies between Bhargavas vs. Brahmins, Bhargavas vs. Chaturvedis, and Brahmins vs. Chaturvedis, these differences were not statistically significant when combined over all 24 STR markers between Chaturvedis vs. Brahmins and Bhargavas vs. Brahmins. The genetic distance analysis revealed that Bhargavas are slightly apart from the other two populations.     

Gene diversity in some Muslim populations of North India

North Indian Muslim populations have historical, linguistic, and socioreligious significance to the Indian subcontinent. Although sociocultural and political dimensions of their demography are well documented, no detailed genetic structure of the populations is available. We have undertaken a survey of the gene frequencies of the ABO, Rh, PTC taste ability, sickling, and G6PD systems for different endogamous groups: Sheikh, Syed, Pathan, Ansari, Saifi, and Hindu Bania. All the groups at most loci showed statistically nonsignificant differences, except for ABO and PTC traits, for which interpopulational differences were seen. Heterozygosity ranged from 0.048 to 0.617 among the Sheikh, 0.149 to 0.599 among the Pathan, 0.105 to 0.585 among the Ansari, 0.25 to 0.869 among the Syed, 0.107 to 0.565 among the Saifi, and 0.100 to 0.492 among the Hindu Bania. The average D(ST) and G(ST) values for the five marker loci were 0.0625 +/- 0.098 and 0.1072 +/- 0.041, respectively. A dendrogram was constructed using the UPGMA clustering method. Our results revealed that the Pathan and the Sheikh form one cluster, the Syed and the Hindu Bania form another cluster, and the two clusters join together (the so-called higher caste); also, the Saifi and the Ansari form a separate cluster (lower caste). The results of the genetic distance analysis are useful for understanding the pattern of genetic relationships between different endogamous groups of Muslims.     

Natural selection and molecular evolution in PTC, a bitter-taste receptor gene

The ability to taste phenylthiocarbamide (PTC) is a classic phenotype that has long been known to vary in human populations. This phenotype is of genetic, epidemiologic, and evolutionary interest because the ability to taste PTC is correlated with the ability to taste other bitter substances, many of which are toxic. Thus, variation in PTC perception may reflect variation in dietary preferences throughout human history and could correlate with susceptibility to diet-related diseases in modern populations. To test R. A. Fisher's long-standing hypothesis that variability in PTC perception has been maintained by balancing natural selection, we examined patterns of DNA sequence variation in the recently identified PTC gene, which accounts for up to 85% of phenotypic variance in the trait. We analyzed the entire coding region of PTC (1,002 bp) in a sample of 330 chromosomes collected from African (n=62), Asian (n=138), European (n=110), and North American (n=20) populations by use of new statistical tests for natural selection that take into account the potentially confounding effects of human population growth. Two intermediate-frequency haplotypes corresponding to "taster" and "nontaster" phenotypes were found. These haplotypes had similar frequencies across Africa, Asia, and Europe. Genetic differentiation between the continental population samples was low (FST=0.056) in comparison with estimates based on other genes. In addition, Tajima's D and Fu and Li's D and F statistics demonstrated a significant deviation from neutrality because of an excess of intermediate-frequency variants when human population growth was taken into account (P<.01). These results combine to suggest that balancing natural selection has acted to maintain "taster" and "nontaster" alleles at the PTC locus in humans.     

Dichromatic colour vision in an Australian marsupial, the tammar wallaby

Despite earlier assertions that most mammals are colour blind, colour vision has in recent years been demonstrated in a variety of eutherian mammals from a wide range of different orders. This paper presents the first behavioural evidence from colour discrimination experiments, that an Australian marsupial, the tammar wallaby (Macropus eugenii), has dichromatic colour vision. In addition, the experiments show that the wallabies readily learn the relationship between the presented colours rather than the absolute hues. This provides a sensitive method to measure the location of the neutral-point, which is the wavelength of monochromatic light that is indistinguishable from white. This point is a diagnostic feature for dichromats. The spectral sensitivity of the wallabies' middle-wavelength-sensitive photoreceptor is known (peak: 539 nm) and the behavioural results imply that the sensitivity of the short-wavelength-sensitive receptor must be near 420 nm. These spectral sensitivities are similar to those found in eutherian mammals, supporting the view that the earliest mammals had dichromatic colour vision. Accepted: 18 July 1999     

甘肃、青海十个民族中苯硫脲尝味能力测定

本文用Harris和Kalmus改良阈值法对甘肃、青海两省汉、回、东乡、保安、藏、裕固、蒙古、撒拉、土、哈萨克等十个民族共计7008人进行了测定。以三号液为味盲界线。结果表明:l)各民族味盲发生率差异极显著(P<0.001),其中保安族味盲发生率是到目前为止我国大陆各民族中发现的仅高于黎族的民族;味盲总发生率与日本人相近。2)各民族总计中男性与女性味盲百分率无显著差异,但尝味阈值女性显著低于男性。3)色觉异常患者与尝味能力的关系与国内外其它学者结果不同,即味盲率和尝味阈值与色觉异常无关。     

Influence of educational levels of the spouses on consanguinity among three endogamous groups of Andhra Pradesh,South India

The highest values of consanguinity was found among “Kamma” (45.0%), “Ediga” (47.5%) and “Mala” (55.7%) who occupy different strata of Indian caste hierarchy. In the way of searchout the factors influencing consanguineous marriages, the present paper finda the negative relationship between educational levels of the spouses and consanguinity. The educational levels of men has significant effect on the frequency of consanguinious marriages among “Kamma” and “Mala”. However, further analysis deplore significant differences in the mean levels consanguinity between educational groups. It divulge low level of higher education among the populations. Only 12% of men and 1.6% of women have degree level and above education in the total sample.