A prenatal genetic counseling is all parents, ideally, offered before the onset of pregnancy to determine risk factors for hereditary diseases. All women planning a pregnancy are certain precautions (eg avoiding teratogenic substances, taking folic acid as a food supplement;. Diet and substitutions recommended to prevent birth defects.) Parents with risk factors about possible consequences and standing for election abklärende investigations informed. If the surveys indicate a disease, reproductive alternatives are discussed.
(Basic principles of medical genetics.) A prenatal genetic counseling is all parents, ideally, offered before the onset of pregnancy to determine risk factors for hereditary diseases. All women planning a pregnancy are certain precautions (eg avoiding teratogenic substances, taking folic acid as a food supplement;. Diet and substitutions recommended to prevent birth defects.) Parents with risk factors about possible consequences and standing for election abklärende investigations informed. If the surveys indicate a disease, reproductive alternatives are discussed. Before conception are available: contraception insemination if the husband is a carrier egg donation if the woman is to be a carrier (.. Ed .: Note d in Germany by the Embryo Protection Act prohibited) After a conception are available: termination of pregnancy Maternal antiarrhythmics to fetal cardiac arrhythmia to treat pre-implantation diagnosis is used to identify genetic defects in embryos conceived by in vitro fertilization, before they are implanted. This can be performed when a pair has a high risk of certain Mendelian diseases or chromosomal abnormalities. Information that is sent when genetic counseling, need simple, not direktiv and free of technical terms to facilitate also anxious anxious pairs understanding. Sometimes frequent repetition is required. The couple should be given to alone time to formulate questions. To many common problems (eg. As advanced maternal age, recurrent spontaneous abortion, previous offspring with neural tube defects or trisomy) receive pairs information over the Internet (www.marchofdimes.com) available. (N. D. Talk .: comparable German web pages are for. B. www.Rund-ums-Baby.de, www.Schwangerschaft.de or www.eumom.com.) Many couples (z. B. those with known or assumed risk factors) benefit from a referral to Genspezialisten that inform about general information and study opportunities. If a fetal malformation is suspected, the patient for ongoing care can be referred to a center that specializes in neonatology. Risk Factors In all pregnancies there is a certain risk for genetic abnormalities. Among the live births, the incidence is for numerical or structural chromosomal abnormalities at 0.5% for einzelgenbedingte (Mendelian) diseases in 1% for polygenic disorders in 1% under the stillbirth rates for anomalies higher. Most malformations that affect a single organ system (z. B. neural tube defects, most congenital heart defect), based on polygenic or multifactorial (d. E. Also influenced by environmental factors) inheritance. For most couples who have already had formerly a fetus or a child with a chromosomal disorder that is the risk of having a child with a chromosomal disorder increases, except a few species (eg., 45-X-triploidy, chromosomal rearrangements ). Chromosome disorders are more likely in case of: fetuses spontaneously dying during the first trimester (50-60%) fetuses with a large malformation (30%; 35 to 38% when submicroscopic anomalies are included) stillbirths (5%) In rare cases, a parent has a chromosomal disorder that increases the risk of a chromosomal disorder of the fetus. Asymptomatic parental chromosome disorders (eg. As balanced anomalies such as certain translocations and inversions) usually can not be seen. A parental balanced chromosomal rearrangement should be suspected when a couple had repeated spontaneous abortions, infertility or a child with a malformation. The chance of a fetal chromosomal abnormality increases with increasing maternal age, because of the advent of nondisjunction increases (failure chromosomes to separate normal) during meiosis. In the case of live births, the rate is: At the age of 20 years, at 0.2% in the age of 35 years at 0.5% At the age of 40 years, at 1.5% in the age of 49 years at 14% Most chromosome disorders are due to a higher maternal age, an extra chromosome (trisomy), in particular trisomy 21 include (down syndrome). Parental age> 50 years increases the risk of some spontaneous dominant mutations, such for the offspring. As achondroplasia. Some chromosomal abnormalities are submicroscopic and thus not be identified by traditional karyotyping. The submicroscopic chromosomal abnormalities occur, regardless of the age-related Nondisjunktion- mechanisms. The exact incidence of these abnormalities is unclear, but the incidence is higher in fetuses with structural anomalies. An autosomal dominant disorder must be accepted if a positive family history in more than one generation is; autosomal diseases affect men and women equally. A parent has an autosomal dominant disorder, it is transmitted with a risk of 50% to an offspring. To have an autosomal recessive disorder are symptomatic, a descendant of both parents must receive a mutated gene for the disease. If the parents are heterozygous (carrier), their clinical appearance is normal. If both parents are carriers, the offspring bear (male or female), a 25% risk of homozygous for the mutant gene and therefore ill to be, 50% are expected to be heterozygous and 25% probably genetically normal. If only siblings and no other relatives are ill, is suspected an autosomal recessive disease. The probability that both parents carry the same autosomal recessive trait is increased when they are blood relatives. Because women have two X chromosomes and men only one, are X-linked recessive disease in all men who carry this mutation, symptomatic. Such diseases are usually passed on by clinically silent heterozygous females (female carriers). Therefore, the risk of suffering from this disease is, for every son of a Konduktorin 50%, and for each subsidiary is the risk of being Konduktorin, also 50%. Ill men do not inherit the gene to their sons, but all daughters who are therefore female carriers. Not sick men do not inherit the gene.