Alpha1-antitrypsin deficiency. 1: epidemiology of alpha1-antitrypsin deficiency.
(49/346)
The protein and molecular characteristics of variants of the alpha1-antitrypsin (AAT) gene are described, and available data on the genetic epidemiology of AAT deficiency are presented. (+info)
The allele frequency spectrum in genome-wide human variation data reveals signals of differential demographic history in three large world populations.
(50/346)
We have studied a genome-wide set of single-nucleotide polymorphism (SNP) allele frequency measures for African-American, East Asian, and European-American samples. For this analysis we derived a simple, closed mathematical formulation for the spectrum of expected allele frequencies when the sampled populations have experienced nonstationary demographic histories. The direct calculation generates the spectrum orders of magnitude faster than coalescent simulations do and allows us to generate spectra for a large number of alternative histories on a multidimensional parameter grid. Model-fitting experiments using this grid reveal significant population-specific differences among the demographic histories that best describe the observed allele frequency spectra. European and Asian spectra show a bottleneck-shaped history: a reduction of effective population size in the past followed by a recent phase of size recovery. In contrast, the African-American spectrum shows a history of moderate but uninterrupted population expansion. These differences are expected to have profound consequences for the design of medical association studies. The analytical methods developed for this study, i.e., a closed mathematical formulation for the allele frequency spectrum, correcting the ascertainment bias introduced by shallow SNP sampling, and dealing with variable sample sizes provide a general framework for the analysis of public variation data. (+info)
Failure to detect DUP25 in lymphoblastoid cells derived from patients with panic disorder and control individuals representing European and American populations.
(51/346)
Investigation of the co-occurrence of panic and phobic disorders with joint laxity led to the identification of interstitial duplications involving human chromosome 15q24-26 (named 'DUP25') in a Spanish population. DUP25 was observed in 97% of patients and in 7% of control individuals. In the present study, we used two different methods to detect DUP25: high-throughput molecular gene dosage analysis and fluorescence in situ hybridization (FISH). We evaluated 56 lymphoblastoid cell lines derived from 26 unrelated patients with panic disorder obtained from several European and American populations and 30 normal controls. We could not find any cell line showing a result consistent with DUP25. These data do not support any association of DUP25 with panic disorder. (+info)
Intraspecific diversity of Yersinia pestis.
(52/346)
Increased interest in the pathogenic potential of Yersinia pestis has emerged because of the potential threats from bioterrorism. Pathogenic potential is based on genetic factors present in a population of microbes, yet most studies evaluating the role of specific genes in virulence have used a limited number of strains. For Y. pestis this issue is complicated by the fact that most strains available for study in the Americas are clonally derived and thus genetically restricted, emanating from a strain of Y. pestis introduced into the United States in 1902 via marine shipping and subsequent spread of this strain throughout North and South America. In countries from the former Soviet Union (FSU), Mongolia, and China there are large areas of enzootic foci of Y. pestis infection containing genetically diverse strains that have been intensely studied by scientists in these countries. However, the results of these investigations are not generally known outside of these countries. Here we describe the variety of methods used in the FSU to classify Y. pestis strains based on genetic and phenotypic variation and show that there is a high level of diversity in these strains not reflected by ones obtained from sylvatic areas and patients in the Americas. (+info)
Progress toward measles elimination--region of the Americas, 2002-2003.
(53/346)
In 1994, countries in the Region of the Americas adopted the goal of eliminating endemic measles transmission in the Western hemisphere by 2000. Since 1994, rapid progress has been made. The number of measles cases has declined >99%, from approximately 250,000 in 1990 to 105 confirmed cases reported in six countries in 2003. During 2003, only Mexico and the United States reported outbreaks. The three chains of transmission in Mexico and two U.S. outbreaks were import-related; a third U.S. outbreak was of unknown source. Since November 2002, no transmission of the D6 and D9 genotypes has been reported; these genotypes were responsible for several large outbreaks in the region during 1997-2002. This report summarizes the epidemiology of measles in the Americas during 2002-2003 and highlights progress toward measles elimination, including the lowest ever number of reported measles cases in the region. Because the region is under constant threat of measles importation from regions where the disease is endemic, countries must maintain high population immunity to measles and sensitive surveillance to ensure the timely detection of imported cases and allow for rapid implementation of control measures. (+info)
Can a minimum rate of investigation of measleslike illnesses serve as a standard for evaluating measles surveillance?
(54/346)
To determine whether measles case finding is sensitive, we developed a standard by which to evaluate measles surveillance. We compiled data on the incidence of measleslike illnesses (MLIs) from multiple, diverse sources and used the distribution of these values to determine the minimum level of measles case-finding activity that could be expected in a given region. Among surveillance programs in the United States, other countries in the Americas, and other World Health Organization regions, the median annual rates for rash investigations that were ruled out for measles were 4.3, 4.1, and 1.8/100000 population, respectively. The annual rates of measles IgM testing in the United States in public laboratories and commercial laboratories were 1.6 and 9.2/100000 population, respectively. In total, we collected data on annual MLI incidence from >80 sources. Values ranged from 0.1 to 22.6 cases of MLI per 100000 population, and 90% of values were >or=1.0/100000 population. On the basis of these findings, we propose that programs attempting measles elimination consider evaluating surveillance by comparing the annual rate of suspected measles investigations against a minimum standard of 1/100000 population. (+info)
Measles eradication in the Americas: progress to date.
(55/346)
The region of the Americas has shown extraordinary progress in its fight to interrupt measles transmission. The Pan American Health Organization's recommended strategy includes the following: a 1-time nationwide campaign targeting 1- to 14-year-old children; routine vaccination among 1-year-olds; and nationwide campaigns conducted every 4 years, targeting all 1- to 4-year-olds. Rapid house-to-house monitoring of vaccination and measles surveillance are other essential components of the strategy. During 2001, only 541 cases were confirmed in the region. In 2002, only Venezuela and Colombia had indigenous transmission. After important vaccination efforts in both countries, the last reported case occurred on 20 September 2002, in Venezuela. Since then, no confirmation exists of indigenous measles circulation anywhere else in the region. Nonetheless, important challenges remain, including insufficient coverage during routine and campaign vaccination and inadequate investigation of some cases. (+info)
Certification of polio eradication: process and lessons learned.
(56/346)
Since the 1988 World Health Assembly resolution to eradicate poliomyelitis, considerable progress has been made towards interrupting the transmission of wild poliovirus globally. A formal process for the certification of polio eradication was established on the basis of experience gained during smallpox eradication. Independent groups of experts were designated at the global, regional, and country levels to conduct the process. The main requirements for the global certification of the eradication of wild poliovirus are the absence of wild poliovirus, isolated from suspect polio cases, healthy individuals, or environmental samples, in all WHO regions for a period of at least three years in the presence of high-quality, certification-standard surveillance and the containment of all wild poliovirus stocks in laboratories. Three WHO regions--the Region of the Americas (1994), Western Pacific Region (2000), and European Region (2002)--have already been certified free of indigenous wild poliovirus. Eradication and certification activities are progressing well in the three endemic regions (African, Eastern Mediterranean, and South-East Asia). Several challenges remain for the certification of polio eradication: the need for even closer coordination of certification activities between WHO regions, the verification of laboratory containment, the development of an appropriate mechanism to verify the absence of circulating vaccine-derived polioviruses in the future, and the maintenance of polio-free status in certified regions until global certification. (+info)