title: [Unstable mutations, new challenges for genetic counseling of inherited disorders].
abstract: Unstable mutations or amplification of DNA tandem repeats sequences constitute a new kind of genetic alteration discovered in the 90's that cause hereditary diseases. This mutation has been found inside or near important genes involved in the normal neurological function in human beings. In some cases, the presence of the amplification causes altered expression of the genes, their inactivation or the synthesis of a protein with new functions. Some common characteristics of these diseases are that they affect the central nervous system and are degenerative in nature. Most of them show genetic anticipation meaning that the severity of the manifestations increases in each generation and appear at an earlier age. In most cases, the severity of the symptoms is positively correlated with the size of the amplification. Twenty illnesses caused by this kind of mutations have been identified so far. Briefly, this work reviews the current knowledge about this topic.
authors.affiliation: Sección de Genética Humana, Instituto de Investigaciones en Salud, Universidad de Costa Rica. pcuenca@cariari.ucr.ac.cr
authors.forename: Patricia
authors.initials: P
authors.lastname: Cuenca
authors.forename: Fernando
authors.initials: F
authors.lastname: Morales
mesh_terms: D005817:Genetic Counseling; D020022:Genetic Predisposition to Disease; D020271:Heredodegenerative Disorders, Nervous System / Q000175:diagnosis / Q000235:genetics*; D006801:Humans; D009154:Mutation / Q000235:genetics*; D011237:Predictive Value of Tests; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*