[The human genome--chromosome 15]

The Prader-Willi syndrome (PWS) with Angelman's syndrome form a pair known above all due to problems of genetic imprinting and uniparental disomy. Both phenomena drew attention to the importance of control of expression of different alleles and their genetic origin. The causes of the two syndromes have not been elucidated unequivocally so far. In case of the PWS, at least, there is the possibility of a gene of the protein carrier of a small nuclear ribonucleic acid described as SNRPN. In case of Marfan's syndrome the responsible gene is the fibrillin gene (FNB1) with the locus on area 15q21. The mentioned gene participates probably also in diseases caused by a change of the vascular wall (aneurysm) and in prolapse of the mitral valves. On the 15th chromosome are several representatives of the family of genes of cytochrome P450 the products of which play a part in the metabolism of exogenous substances, incl. pharmaceutical ones. Their activity is part of the natural sensitivity or resistance to some chemical cancerogens. The postscriptis devoted to the assumed locus of dyslexia DLX1.