We present a patient with partial monosomy of the short arm of chromosome 18 caused by de novo translocation t(Y;18) and a generalized form of keratosis pilaris (keratosis pilaris affecting the skin follicles of the trunk, limbs and face-ulerythema ophryogenes). Two-color FISH with centromere-specific Y and 18 DNA probes identified the derivative chromosome 18 as a dicentric with breakpoints in p11.2 on both involved chromosomes. The patient had another normal Y chromosome. This is a third report the presence of a chromosome 18p deletion (and first case of a translocation involving 18p and a sex chromosome) with this genodermatosis. Our data suggest that the short arm of chromosome 18 is a candidate region for a gene causing keratosis pilaris. Unmasking of a recessive mutation at the disease locus by deletion of the wild type allele could be the cause of the recessive genodermatosis.
In clinical medicine, the phenomenon of polypathy, as a particular object of investigation, was first put forth by French clinicians at the end of the 19th century through the "arthritismus" doctrine. In the first half of the 20th century, German paediatricians singled out "syntropias," which are combinations of diseases with common pathophysiological mechanisms, and "dystropias," which are diseases that rarely co-occur in one individual. In the present paper, syntropy/dystropy is defined as a natural generic nonrandom phenomenon with an evolutionary-genetic basis. The genes involved in the development of syntropy are called "syntropic genes," whereas the genes that co-participate in pathophysiological mechanisms and prevent the co-occurrence of particular phenotypes are called "dystropic genes." Prospects for studying the genetic basis of this phenomenon are highlighted. The publicly available database HuGENet can be used in order to identify syntropic genes, as will be shown as examples in an analysis of cardiovascular diseases.
Alu elements, the largest family of interspersed repeats, mobilize throughout the genomes of primates by retroposition. Alu are present in humans in an excess of 500 000 copies per haploid genome. Since some of the insertion alleles have not reached fixation, they remain polymorphic and can be used as biallelic DNA marker systems in investigations of human evolution. In this study, six polymorphic Alu insertional (PAI) loci were used as genetic markers. These markers are thought to be selectively neutral. The presence of these six PAIs was determined by a polymerase chain reaction (PCR)-based assay in 1646 individuals from 47 populations from around the world. Examination of the populations by plotting the first and second principal components, shows the expected segregation of populations according to geographical vicinity and established ethnic affinities. Centroid analysis demonstrated that sub-Sahara populations have experienced higher than average gene flow and/or represent larger populations as compared to groups in other parts of the globe and especially to known inbreed populations. This is consistent with greater heterogeneity and diversity expected of source groups. In addition, maximum likelihood (ML) analyses were performed with these 47 populations and a hypothetical ancestral group lacking the insertion in all six loci. Analysis of our data supports the Out of Africa hypothesis. African populations and admixed groups of African descent formed a single monophyletic group with a basal placement on the tree, which grouped closest to the hypothetical ancestor.
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