Genetic risk
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REVIEW
Genetic risk Leo P. ten Kate
Received: 21 July 2011 / Accepted: 4 October 2011 # The Author(s) 2011. This article is published with open access at Springerlink.com
Abstract In this paper I will review different aspects of genetic risk in the context of preconception care. I restrict myself to the knowledge of risk which is relevant for care and/or enables reproductive choice. The paper deals with chromosomes, genes and the genetic classification of diseases, and it explains why Mendelian disorders frequently do not show the expected pattern of occurrence in families. Factors that amplify genetic risk are also discussed. Of the two methods of genetic risk assessment— history taking and genetic screening—the former method is examined to some extent, and the consequences of an inadequate family history are illustrated in a case report. The paper ends with a review of the sparse literature available on the frequency of a positive family history and an outline of the challenges and rewards faced by professionals when confronted with a positive history.
Introduction Genetic factors are of paramount importance for normal development and health. Abnormal genes and abnormal expression of genes may therefore lead to birth defects and diseases. Although the same applies for many exogenous factors, I focus here on the genetic ones. A further focus will be on genetic factors whose knowledge is of relevance for reproductive choice. Psychological and ethical issues will be discussed in the papers by Riedijk et al. (this issue) Special Issue: Genetic Aspects of Preconception Consultation in Primary Care L. P. ten Kate (*) Department of Clinical Genetics, VU University Medical Center, Amsterdam, The Netherlands e-mail: [email protected]
and De Wert et al. (this issue); future methods of genetic risk assessment will be discussed in the paper by Ropers (this issue).
Relevance of knowledge of genetic risk Two main reasons for identifying genetic risk in the preconception period are that preconception knowledge of genetic risk may influence care and also may allow informed reproductive choice. Knowledge of genetic risk may influence preconception care, prenatal care, mode of delivery and postnatal care. Previous birth of a child with a neural tube defect—a multifactorial genetic condition— indicates a higher dose of folic acid supplementation preconceptionally and in the first months of pregnancy, than for a woman without neural tube defects in her family (Grosse and Collins 2007). Preeclampsia in a sister of a pregnant woman leads to a higher level of alertness for related symptoms during prenatal care. Dexamethasone treatment in an unborn sib of a child with congenital adrenal hyperplasia has to start as soon as the pregnancy is confirmed, well before invasive prenatal diagnosis of the foetus is possible (Nimkarn and New 2010). Preconception knowledge of genetic risk also allows informed reproductive choice. Consider a couple in which both partners are carriers of an autosomal recessive disease like cystic fibrosis. What
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