Indian Journal of Human Genetics
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Item Lessons To Be Learned From Atavistic Mutations.(1995-01) Ohno, SusumuAs a result of tetraplodization events in their past, the carp and the goldfish of the teleost order cypriniformes, as well as trouts and salmons of the order salmoniformes created redundancy at every locus. From the extinct rate of these redundant genes, the half-life of genes that became nonessential has been estimated in the range between 350 to 150 million years. The prediction that the trace of teraploid evolution can also be found in the mammalian genome appears to have been fulfilled. For example, in both man and the mouse, a set of genes encoding keratins, homeobox proteins and type I collagen a-chain is found not on one chromosome but on two nonhomologous chromosomes, as the original and its duplicate, thus indicating the conservation of paralogous segments since the teraploidization event that took place in our crossopterygian ancestor some 350 million years ago. It thus appears that genes more often than not remain immortal even after they become redundant, therefore, nonessential. This immortality also explains frequent recurrence of atavistic mutations: e.g., sperm whales re-growing a pair of hind legs 2.5 meters long and the horse of the order Perisodactyla sporting a pair of horns. It would be recalled that Michelangelo invariably adorned the head of Moses with a pair of horns.Item A Deficit Of Parental Consanguinity In Some Autosomal Recessive Diseases.(1995-01) Bundey, SarahThe observation of a deficit of a consanguineous parents in diseases thought to be inherited as autosomal recessives is as intriguing as a deficit of affected sibs. There are several possible explanations. The most likely is that new dominant mutations account for a proportion of patients, and this probably applies to all three diseases here. This explanation would also explain the reduced segregation in sibs. The second explanation is the most interesting, namely that neighbouring alleles are lethal in the homozygous state. This would lead to the non-ascertainment of consanguineous families in whom these "back" alleles co-existed. However this hypothesis would not explain a deficiency of affected sibs. The last explanation involves the action of mutant alleles (heterozygous or homozygous) at a second unlinked locus, which are essential for manifestation, but which do not cause disease on their own. The requirement of two pairs of unlinked recessive alleles for manifestation would give rise to a segregation ratio of 0.0625 or more, the requirement of two unlinked dominant loci would produce a segregation ratio of 0.25 and both situations would be associated with an unexpectedly low parental consanguinity rate.Item Human Genetics Update.(1995-01) Indian Journal of Human GeneticsItem Biomonitoring Individual Risk In Relatives of Breast Cancer Patients by Comet Assy.(1995-01) Rajeswari, NEstimation of genetic instability by direct quantitation of DNA damage and repair is an important aspect in biomonitoring an individual's risk to cancer. Single cell gel electrophoresis (SCGE) assay or comet assay was carried out on breast cancer patients, their first degree relatives, and controls for the first time for evaluating the basal DNA damage, individual’s susceptibility towards mutagen and repair efficiency. The mean DNA damage in untreated, treated and repaired leucocytes increased significantly from controls to cancer patients. First degree relatives of breast cancer patients showed a significantly higher mean DNA damage than the control group but lesser damage when compared to cancer patients. Among the breast cancer family members, the females showing a relatively high mean DNA damage in untreated, treated and repaired leucocytes, as well as having highly damaged individual cells would be considered as carrying the predisposing factors for cancer development.Item HLA and Disease Susceptibility in Tamil Nadu, S. India.(1995-01) Pitchappan, R M; Balakrishnan, K; Mahendran, V; Brahmajathi, VResult on HLA polymorphism in the populations of Tamil Nadu, South India are analysed for HLA association with various diseases like pulmonary tuberculosis, leprosy, psoriasis, rheumatoid arthritis, iridocyclitis and Eale's disearse. These studies revealed: i) association of psoriasis with HLA B17 and DR7 is highly significant in Vellala related group and this is attributed to founder effect-hitch hiking of a disease producing gene linked to these alleles, as the population migrated, ii) different castes differ from one another in their HLA allelic and haplotype polymorphism, iii) HLA DR2 predispose for more severe from of pulmonary tuberculosis which transcends ethnic barrier, the susceptibility presumably being due to a generalized MHC dependent immunogenetic and pathological mechanism, iv) HLA B27 and DR4 are associated with iridocyclitis, rheumatoid arthritis and low back pain; the susceptibility may be a HLA dependent molecular mimicry process, v) HLA alleles DR2 and DR4 predispose for severe forms of the respective diseases, though not for initial susceptibility.Item Biochemical Characterization of a Fast Moving G6PD Variant - G6PD 'INSULI'.(1995-01) Mudera, V C; Mukherjee, M B; Sayyed, Z; Rao, V RG6PD 'Insuli', a fast moving electrophoretic variant is detected and biochemically characterised, first time in india in a Sunni Muslim family of Maharashtra. The enzyme kinetics and electrophoretic mobility of the variant are similar to Negro type A. As direct evidence for the Negro admixture in the population is lacking, the variant is considered new until further molecular evidence.Item Molecular Analysis Of The Additional X-Chromosome In Klinefelter's Syndrome Patients.(1995-01) Mohapatra, I; Kucheria, K; Ammini, A CThe parental origin of the extra X chromosome in five families with Klinefelter's syndrome (47,XXY) was studied DNA restriction fragment length polymorphisms (RFLPs). In four, the extra X chromosome was maternal in origin and one it was paternal. Four X-linked marker loci were used and we were able to specify the origin of the extra X chromosome in all cases. The parental origin of the extra X chromosome in five families with Klinefelter's syndrome (47,XXY) was studied DNA restriction fragment length polymorphisms (RFLPs). In four, the extra X chromosome was maternal in origin and one it was paternal. Four X-linked marker loci were used and we were able to specify the origin of the extra X chromosome in all cases. The parental origin of the extra X chromosome in five families with Klinefelter's syndrome (47,XXY) was studied DNA restriction fragment length polymorphisms (RFLPs). In four, the extra X chromosome was maternal in origin and one it was paternal. Four X-linked marker loci were used and we were able to specify the origin of the extra X chromosome in all cases. The parental origin of the extra X chromosome in five families with Klinefelter's syndrome (47,XXY) was studied DNA restriction fragment length polymorphisms (RFLPs). In four, the extra X chromosome was maternal in origin and one it was paternal. Four X-linked marker loci were used and we were able to specify the origin of the extra X chromosome in all cases.Item Simple Repeat Polymorphisms.(1995-01) Indian Journal of Human GeneticsItem Familial marker in a Down Syndrome Child.(1995-01) Rajangam, Sayee; Varghese, Mini; Lincoin, Shavanthi; Lyer, Uma; Thomas, I MFour months old, female child, referred for cytogenetic analysis, showed mosaiciam for the marker chromosome. Her karyotype: 47,XX,+21/48,XX+21 mar (pat). The karyotype of her mother & her sib were normal. Her father showed, similar to the proband, mosaicism for the marker ie 46,XY/47,XY, + mar. AgNOR technique determined the marker as fused short arms of the acrocentric chromosome. Four months old, female child, referred for cytogenetic analysis, showed mosaiciam for the marker chromosome. Her karyotype: 47,XX,+21/48,XX+21 mar (pat). The karyotype of her mother & her sib were normal. Her father showed, similar to the proband, mosaicism for the marker ie 46,XY/47,XY, + mar. AgNOR technique determined the marker as fused short arms of the acrocentric chromosome.Item Frequency of Twinning in India.(1995-01) Sharma, KishanTwinning frequency in India has been studied on data derived from primary and secondary sources. Preliminary results on twinning rates in the state of Punjab have presented from fertility history of 101 Gujjar mothers and from delivery records of a public hospital for the year 1987. The former sample showed much higher twinning rate (30.2 per 1000 births). (19.2 per 1000 births). The above results were compared with those from other Indian studies. Further 51 regional samples drawn from different Indian states were analyzed for studying regional trends. Though no definite trend emerged from the analysis, the twinning rate was the highest in Uttar Pradesh and the lowest in Tamilnadu. The Indian data also revealed secular trends in twinning rates, as seen in many other countries.Item Seminar on Genetic Epidemiology and XX Annual Conference of the Indian Society of Human Genetics, Dec 11-13, 1994.(1995-01) Indian Journal of Human GeneticsItem Exploting The Informativity Of "Meaningless" Simple Repetitive DNA From Indirect Gene Diagnosis To Multilocus Genome Scanning. Indian Journal of Human Genetics. 1995 Jan; 1(1): 7-10.(1995-01) Jorg, T Epplen; Winfried, Maueler; Cornelia, EpplenMost eukaryotic genomes are characterized by excessively large amounts of non-coding DNA sequences among which redundant (repetitive) elements constitute a sizable portion. The functional role of abundant subclass of repetitive sequences - simple, tandemly arranged repeats - remained mysterious so far. Even the biological meaning of most of these elements appears quite refractory to present-day techniques in molecular genetics. Notwithstanding simple repetitive sequences have been developed into superb tools for various aspects of eukaryotic genome research : Using oligonucleotide probes carrying simple repeat motifs multilocus DNA fingerprinting can be applied for individual identification and genetic relationship analyses in plants, animals and humans. Microsatellilte analyses via polymerase chain of simple repeat blocks allow for efficient investigations of such divers subject matters as criminal stains, detailed genome maps and indirect gene diagnoses.Item ABO Blood Group Antibodies and ABH Secretion In Duodenal Ulcers.(1995-01) Pratibha, N; Padma, T; Murty, J SThe association of the ABO antigen-antibody titres with the ABH secretor status in duodenal ulcers was examined in a sample of 196 patients and 182 healthy controls. The risk for group A and group B patients depended upon the strengths of the antigens and the ABH secretor status. Further the risk was high for low antibody titres in non-secretor patients than in secretor patients. Increased demand on the antibodies for mucoprotection in the absence of the A and B antigens in the gastro-intestinal mucosa or insufficient production of antibody by the lymphocytes could be the possible reasons.Item Protein Genetics and Paternity Determinations in Southern Brazil.(1995-04) Robinson, W M; Hickmann, A C; Weimer, T A; Franco, M H L P; Geiger, C J; Salzano, F MA review is made of 961 cases of paternity determinations using a battery of 18 protein genetic systems. With this set, the a priori probability of exclusion is 89% but only 16% of the accused men were exonerated. Among the non-excluded, 55% had probabilities of 95% or more of being the father of the child considered. The results are in accordance with those from other centers which use equivalent sets of protein markers. When the direct study of DNA is not possible, these tests provide a relatively low-cost, reliable alternative for such determinations.Item Guidelines on Ethical Issues In Medical Genetics And The Provision Of Genetics Services.(1995-04) Wertz, D C; Fletcher, J C; Berg, Kare; Boulyjenkov, VItem Effect Of Inbreeding On Gestational Period And Anthropometric Measurements At Birth In North India.(1995-04) Badruddoza; Afzal, Mohd; Ali, ManazirThe effect of consaguinity on gestational period, birth weight, recumbent length, head circumference and chest girth at birth in a group of 2264 babies (1174 males, 1090 females) delivered in Aligarh during March 1989 to 1991 has been studied. Means and regression coefficients revealed a reduction in all the measurements with inbreeding.Item Genetic Counselling in a Case of Usher Syndrome Type III.(1995-04) Ramesh, A; Sabitha, RUsher Syndrome is a recessive disease characterised by dual sensory impairment. We report a case of Usher Syndrome, probably of Type III, characterised by post-lingual progressive sensorineural hearing loss and retinitis pigmentosa who sought genetic counselling.Item Marker Chromosome in a Turner Patient.(1995-04) Kulkarni, S; Ammini, A C; Kucheria, KOut of the twenty seven suspected cases of Turner Syndrome analysed during 1993-1995, eleven had the chromosome pattern of 45,X; fifteen had 45,X / 46,XX and one had mosaic pattern of 45,X / 46,X, +mar. The paper discusses a patient with the mosaic chromosome pattern of 45,X / 46,X, +mar showing most of the Turner stigmata. The marker chromosome was seen in the 76% of the metaphases analysed. It was too small and G, C, Q banding could not confirm the origin. The position of the marker chromosome was random and no significant centromeric association was seen. It is well documented that the patients with the dysgenetic gonads and the presence of Y material has increased risk of malignancy. The origin of the marker chromosome is discussed in relation to phenotypic features.Item Mutational Pathways in Colorectal Carcinoma Cell Lines.(1995-04) Bhattacharyya, N P; Meuth, MWe studied the nature of mutational events in two highly malignant human colorectal carcinoma cell lines. In HCT116, the frequency of micro-satellite instability as detected by the electrophoretic shifts in the allele sizes of micro-satellite DNA sequence was 22% and 80% in two loci (D16S303 and D16S295) of dinucleotide repeats. In SW620, we failed to detect such mutation at any of the two micro satellite loci studied. However, there was a high frequency loss of heterozygosity in the micro satellite locus D16S303. Such high frequency loss of the D16S303 allele extended to other linked loci covering about 9 mega base pairs (Mbp). This set of data indicates that at least two pathway are involved in the development of colon tumour.Item Localisation Of The Usher Syndrome Type I Gene In The French Acadian Population Of Louisiana To Chromosome 11p14-p15.1 By Linkage and Haplotype Analysis.(1995-04) Ayyagari, Radha; Smith, Richard J H; Polymeropoulos, Mihael; Daiger, Stephen P; Pelias, Mary Z; Wozencraft, Laura; Kaiser-Kupfer, Muriel; Hejtmancik, Fielding JThe Usher syndromes (USH) are autosomal recessive diseases characterised by congenital sensorineural hearing loss and progressive pigmentary retinopathy with or without vestibular dysfunction. At least three distinct loci causing type 1 Usher syndrome (USH1) have been reported, with the USHl locus found in the French-Acadian families of Louisiana (USHlC) mapping to chromosome 11p. In this study 16 microsatellite markers were used to refine the position of the USH1 locus in the French-Acadian population of Louisiana. Two-point linkage analysis showed no recombination between US1C and D11S419 (Zmax = 2.95), D11S902 (Zmax = 6.44), D11S921 (Zmax = 3.31), and D11S899 (Zmax = 5,46). A map of chromosome 11p14-15.1 based on microsatellite markers was developed for use in mapping USH1C. Multipoint linkage analysis gave Z = 6.5 at D11S899 with a one-lod confidence interval covering 5 cM interval. The closest flanking markers showing obligate recombinants are D11S861 and D11S928, which localises USH1C to a 9 cM interval. However, examination of the marker haplotypes in individuals affected by USH1C is consistent with the suggestion that the high icnidence of USH1 in this population is the result of a founder effect and places the USH1C locus in the 5cM interval bounded by D11S861 and D11S899.