Papers Published by Academic Staff
Department of Anatomy
Faculty of Medicine, University of Colombo, Sri Lanka.
Genetic Variation in Sri Lanka - S.S.Papiha, S.S. Mastana, and R. Jayasekera
A population genetic study was designed to analyze genetic composition and population structure of the five main population groups (Sinhalese, Tamils, Moors, Burghers, and Malays) of Sri Lanka. Twenty-seven polymorphic and three monomorphic loci were examined in all five populations. Several genetic markers, including subtype variation of HP, TF, PI, GC, ORM, and PGM1, were analyzed for the first time and helped to clarify the range of genetic variation for Sri Lankan populations. Many genetic systems (Rh, JK, ACP, ESD, HP, C3, TF, and GC) showed a high level of variation among the populations of Sri Lanka. However, at the individual level the Burgher population (a hybrid group between the Dutch and Portuguese and the local Sinhalese) showed European features, but its gene frequencies were either intermediate to its parental populations or more similar to the local Sinhalese. In the F statistic analysis all populations showed positive FIS values, ranging from 0.0305 in the Burghers to 0.1084 in the Malays; however, for a large number of loci the FIS values for the Burghers were negative, indicating the possible hybrid nature of this population. In genetic affinity studies the Burghers, Moors, and Malays showed a greater degree of isolation, but compared with the possible populations of their origin, the five populations of Sri Lanka tended to show some degree of affinity to each other. Our analysis therefore suggests that there is little evidence of disruptive selection; however, restricted gene flow favors the change of allele frequency toward the local Sinhalese and Tamil populations.
Human Biology: Volume 68, No. 5, October, 1996, pp 707-737
Population Genetic Study of Three VNTR Loci (D2S44, D7S22, and D12S11) in Five Ethnically Defined Populations of the Indian Sub Continent - S.S.Papiha, S.S. Mastana, R. Jayasekera, and R. Chakraborty.
Abstract - Using RFLP (restriction fragment length polymorphism) analysis, we have characterized the genotype variation of three VNTR (variable number of tandem repeat) loci (D2S44, D7S22, and D12S11) with probes YNH24, g3, and MS43a, respectively, for 288 individuals from 5 genetically well defined ethnic groups (Brahmins, Maratha, Gujarati Patel, Sinhalese, and Moors) of the Indian Subcontinent. The distributions of VNTR alleles at the binned level were examined among the five populations, and the genetic affinities obtained using the VNTR data were compared with serogenetic data on 22 blood group and protein loci previously reported from our laboratory. For classical genetic markers the Sinhalese show slight affinity with the populations of western India. However, the genetic affinity results considerably parallel the results for VNTR loci and 25 combined VNTR/blood group/ protein loci, suggesting that the Sinhalese show the least affinity with the populations of western India. These results confirm the findings of a recent study of genetic relationships of the populations of Sri Lanka based on admixture analysis. The concern regarding whether or not the pattern of genetic variation of VNTR loci at the bin level can be studied using classical population principles are addressed.
Human Biology: Volume 68, No. 5, October, 1996, pp 819-835.
Acceptance of a Genetic Service in Sri Lanka: A Student Viewpoint - R. Jayasekera
Summary - The attitudes of a group of final year medical students of the Faculty of Medicine, Colombo, on the establishment of a Genetic Service with genetic counselling, prenatal diagnosis and therapeutic abortion as its main components, have been analyzed. More than 70% of the respondents reacted positively to various aspects of the three genetic components. Of the variables sex, religion and awareness of the existence of a Human Genetics Unit providing genetic counselling, only religion had a significant impact on the response "genetic counselling is both a useful and necessary medical service,"
Ceylon Journal of Medical Sciences: Volume 29, No.2, December, 1986, pp. 67-73.
Chromosome Anomalies in Sri Lanka : A Cytogenetic Profile - R. Jayasekera
Abstract - The spectrum of chromosome anomalies detected in a population referred to the Human Genetics Unit, Faculty of Medicine, Colombo, using lymphocyte culture and Giemsa banding technique, is reported. The availability and usefulness of chromosome analysis and its direct application in the preventive and curative aspects of medicine is stressed.
Down syndrome showed a significantly high incidence, but with an unexpectedly high frequency of trisomy 21 due to non-disjunction in young parents. The possibility of the existence of other genetic or environmental factors stronger than the influence of ageing gametic cells, which might trigger off non-dysjunction in young Sri Lankans, is suggested.
Ceylon Journal of Medical Sciences: Volume 31, No. 1, June, 1988, pp 1-5.
Factors influencing the age at natural menopause in Sinhalese women - R. Jayasekera
In this preliminary study, the median age at natural menopause for Sinhalese women was determined as 51.12 years and the effects of socio-demographic, menstrual and reproductive factors on the age at natural menopause were studied. The age at menarche, the socio-economic class and age of the subjects at their first live births did not have significant predictive value in establishing age at onset of natural menopause. However women who had no live births or one birth, reached menopause significantly earlier than those who had two or more live births. The effect of a prolonged menopause on women is discussed.
The Ceylon Journal of Medical Science: Volume 37, No.1, June, 1994; pp 23-27.
Oral Abnormalities in 45 XO Turner Syndrome in Sri Lanka - R. Jayasekera, M.T.M. Jiffry
Summary - Fourteen 45 XO Turner patients were examined for oral deformities. High vault palate was noticed amongst fifty percent of them. All of them had some form of oral defect. Therefore, this preliminary study shows the importance of early dental care needed for Turner syndrome.
Sri Lanka Dental Journal - Volume 18 and 19(88/89 and 89/90), pp 36-39.
The Influence of Socio-Economic Factors on Mean Age of Menarche in Sri Lanka - R.Jayasekera, S. Goonawardene
Summary - The effect of socio-economic factors on the age of menarche were studied in 3967 Sinhalese girls in Colombo to ascertain the role of environment on the onset of menarche. The mean age of menarche in this group was found to be 13.06± 0.18 years, unaffected by father's occupation, family size or birth order. The age distribution of this sample was very similar to a National Health Survey carried out from 1960-1970 in the U.S.A. A secular effect as an earlier mean menarcheal age was also observed in a ten year period(1974-1984), which paralleled a trend towards a suggested improvement in the socioeconomic status of the population. The earlier appearance of menarche would have significant impact on the educational, social and health policies of the country in its quest to achieve "Health for all by the year 2000". In view of an earlier onset of menarche and a longer reproductive period, sex education may have to be introduced into schools earlier than at present and possibly be integrated into the pattern of upbringing within the family. This would have to be supported by the provision of proper training and facilities. From a legal point of view the age of emancipation of the female may have to examined in the light of these findings and certain policies may have to be implemented in the area of family health and family planning.
The Ceylon Medical Journal: Volume 32, No.2, June, 1987, pp 89-94.