[Importance of genetic counseling in inborn errors of metabolism].

In genetic counselling a detailed history including the family tree and the collection of old and new data lead to a comprehensive knowledge of the illness of the patient. Nevertheless it is important that the metabolic disease is defined as exactly as possible. Enzymatic examinations and genetic diagnosis at the molecular level should be performed for optimal counselling. In descendants of consanguinic pairs the incidence of inborn errors of metabolism is increased. Although in most cases autosomal recessive inheritance gives a clear picture of the well-known risks for the offspring, the individual possibility exists that different alleles could combine to different genotypes with variable phenotypic expression. Loading tests for detecting heterozygotes have become less important with the introduction of probes.