ABSTRACT
BACKGROUND: Down syndrome (DS) and sex chromosomal aneuploidy (SA) are common chromosomal anomalies causing congenital malformations and mental retardation in humans. The well-established risk factor, advanced maternal age, was not found in many of the DS and SA cases in India, while the other possible risk factors have not been well studied. In view of this, the present study has been made. MATERIALS AND METHODS: During the last 5 years, 150 clinically suspected DS and 25 SA cases were referred to our laboratory for chromosome investigation from major hospitals of Mysore city. Chromosome preparations were made from these patients after informed consent was obtained. Well-spread G-banded metaphase plates were analyzed by automated LEICA KARYO software. Two hundred and 100 randomly selected families belonging to different religions were used as controls for the DS and SA cases, respectively. Statistical analysis was carried out using logistic regression RESULTS: Out of the 150 cases of DS, 122 had free trisomy 21, two were mosaic trisomy 21, and one had translocation. Logistic regression of case-control study of DS children revealed that the odds ratio of uncle-niece marriages, or second cousin marriages, or parents lived in rural region, or exposure of the parents to chemicals, or parents education status, or habits (tobacco/ alcohol used) of father, or mother not undergone prenatal scanning, or mothers with previous abortions were significant when all the variables of that category were used one at a time. Exposure of the parents to chemicals, parents’ educational status, habits (tobacco/alcohol use) of the father, mother not undergone prenatal scanning, and history of previous abortions were significant when all the variables of that category were used one at a time. Similarly, except for consanguinity, history of previous abortions, and mother not undergone prenatal scanning, all other factors showed significant odds ratios in SA cases. CONCLUSION: Besides the known risk factors, consanguinity, region (rural/urban) of residence of parents, exposure of parents to chemicals, educational status of parents, habits of father, prenatal scanning, and reproductive performance of mother are possible risk factors for chromosomal aneuploidy.
ABSTRACT
BACKGROUND: The ability to taste phenylthiocarbamide (PTC), a bitter chemical has long been known to be a heritable trait, which is being widely used for both genetic and anthropological studies. The frequency of taster and non-taster allele is found to vary in different populations. AIMS AND OBJECTIVE: To investigate the frequency of taster trait in Mysore, South India. MATERIALS AND METHODS: The present investigation was conducted in Mysore, South India during 2002 - 2003. About 3282 subjects irrespective of age, sex, religion, food habits, socio-economic status were randomly selected from various parts of the city and a total of 180 families, which included Christian (50), Hindu (61) and Muslim (69) were screened from different localities of the city. Harris and Kalmus method was used to assess the PTC taster and nontaster phenotype. RESULTS: It was found that tasters were significantly more frequent than nontasters in all the four categories. The incidence of tasters was more in unbiased category (85%) and less in Muslim category (58%). Investigations on PTC tasting in the families of three different religious groups revealed that the tasters were significantly more frequent than nontasters. It was also found that heterozygous father or mother for the taster genes with nontaster partner had taster and nontaster progenies in the ratio 1.0: 1.54 indicating the deviation in the segregation pattern of test cross. CONCLUSION: In Mysore, tasters are more frequent than nontasters. Variation in the frequency of nontaster allele in the religious groups could be due to inbreeding.