Browsing by Author "Chakraborty, R"

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    Genotypic interaction between DRD4 and DAT1 loci is a high risk factor for attention-deficit/hyperactivity disorder in Chilean families
    (WILEY, 2006) Carrasco, X; Rothhammer, P; Moraga, M; Henriquez, H; Chakraborty, R; Aboitiz, F; Rothhammer, F
    Attention-deficit/hyperactivity disorder, ADHD [MIM 126452], is a common, highly heritable neurobiological disorder of childhood onset, characterized by hyperactivity, impulsiveness, and/or inattentiveness. As part of an ongoing study of AMID, we carried out a family-based discordant sib-pair analysis to detect possible associations between dopamine receptor D4 (DRD4) and dopamine transporter 1 (DAT1) polymorphisms and ADHD in Chilean families. Both loci individually classified as homozygotes or heterozygotes for the DRD4 7-repeat and DAT1 10-repeat alleles, did not exhibit genotype frequency differences between affected children and their healthy siblings (Fisher's exact test P > 0.25 in both cases). However, the simultaneous presence of both DRD4 7-repeat heterozygosity and DAT1 10 allele homozygosity were significantly higher (34.6%) in cases (26), compared with their unaffected siblings (25) (4%; Fisher's exact test P = 0.0096; odds-ratio, OR = 12.71). Increased density of dopamine transporter in ADHD brains, along with abundance of 7-repeat D4 receptors in prefrontal cortex, which is impaired in ADHD patients, make the observed gene-gene interaction worthy of further incisive studies. (C) 2005 Wiley-Liss, Inc.
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    Mitochondrial DNA polymorphisms in Chilean aboriginal populations: Implications for the peopling of the southern cone of the continent
    (WILEY, 2000) Moraga, ML; Rocco, P; Miquel, JF; Nervi, F; Llop, E; Chakraborty, R; Rothhammer, F; Carvallo, P
    The mitochondrial DNAs (mtDNAs) from individuals belonging to three Chilean tribes, the Mapuche, the Pehuenche, and the Yaghan, were studied both by RFLP analysis and D-loop (control region) sequencing. RFLP analysis showed that 3 individuals (1.3%) belonged to haplogroup A, 19 (8%) to haplogroup B, 102 (43%) to haplogroup C, and 113 (47.7%) to haplogroup D. Among the 73 individuals analyzed by D-loop sequencing we observed 37 different haplotypes defined by 52 polymorphic sites. Joint analysis of data obtained by RFLP and sequencing methods demonstrated that, regardless of the method of analysis, the mtDNA haplotypes of these three contemporary South American aborigine groups clustered into four main haplogroups, in a way similar to those previously described for other Amerindians. These results further revealed the absence of haplogroup A in both the Mapuche and Yaghan as well as the absence of haplogroup B in the Yaghan. These results suggest that the people of Tierra del Fuego are related to tribes from south-central South America. (C) 2000 Wiley-Liss, Inc.