[From the genotype to the phenotype].
The growing knowledge of the molecular anatomy of the human genome and the mechanisms of the gene expression, together with recent advances in molecular epidemiology, have nurtured an entirely different view of the complex relationships between genes and phenotype. This review begins with a brief description of the different types of molecular lesion that may occur in a particular gene sequence as well as the biological consequences that they originate. Then, a "molecular view" of various concepts of classical genetics is presented: dominance and recessiveness are discussed as a problem of cellular homeostasis whereas gene penetrance and expressivity are viewed as problems of variability, gene connectivity and functional pleiotropism. Based on these concepts a few final remarks focus on the relationship between genes and the environment and its enormous impact in the genesis of polygenic and multifactorial disorders.
Parreira
L
L
Instituto de Histologia e Embriologia, Faculdade de Medicina de Lisboa. hleonor@fml.ul.pt
D005786:Gene Expression Regulation / Q000235:genetics; D005787:Gene Frequency / Q000235:genetics; D005799:Genes, Dominant / Q000235:genetics; D005808:Genes, Recessive / Q000235:genetics; D015894:Genome, Human; D005838:Genotype; D006801:Humans; D009154:Mutation / Q000235:genetics; D010641:Phenotype