医学遗传学20遗传咨询engv.ppt

20 遗传咨询Genetic Counseling,Genetic counseling is the process evaluating family history and medical records ordering genetic tests evaluating the results of this investigation helping parents understand and reach decisions about what to do next,Genetic tests are done by analyzing small samples of blood or body tissues.They determine whether you,your partner,or your baby carry genes for certain inherited disorders.,1.Genetic Counselors,Genetic counselors are health professionals with specialized graduate degrees and experience in the areas of medical genetics and counseling.,Most enter the field from a variety of disciplines,including biology,genetics,nursing,psychology,public health and social work.,Genetic counselors work as members of a healthcare team,providing information and support to families who have members with birth defects or genetic disorders and to families who may be at risk for a variety of inherited conditions.,They identify families at risk,investigate the problem present in the family,interpret information about the disorder,analyze inheritance patterns and risks of recurrence,and review available options with the family.,Genetic counselors also provide supportive counseling to families,serve as patient advocates,and refer individuals and families to community or state support services.,They serve as educators and resource people for other healthcare professionals and for the general public.,Some counselors also work in administrative capacities.Many engage in research activities related to the field of medical genetics and genetic counseling.,2.Who Should See One,Most couples planning a pregnancy or who are expecting dont need genetic counseling.,About 3%of babies are born with birth defects each year,according to the U.S.Centers for Disease Control and Prevention-and of the malformations that do occur,the most common are also among the most treatable.,Cleft palate and clubfoot,two of the more common birth defects,can be surgically repaired,as can many heart malformations.,The best time to seek genetic counseling is before becoming pregnant,when a counselor can help assess your risk factors.But even after he become pregnant,a meeting with a genetic counselor can still be helpful.,For example,severalbabieshave been diagnosed with spina bifida before birth.Recent research suggests that delivering a baby with spina bifida via cesarean section can minimize damage to the babys spine-and perhaps reduce the likelihood that the child will need a wheelchair.,You should consider genetic counseling if any of the following risk factors apply to you:(1)if a standard prenatal screening test(such as the alpha fetoprotein test)yields an abnormal result(2)if an amniocentesis yields an unexpected result(such as a chromosomal defect in the unborn baby),(3)if either parent or a close relative has an inherited disease or birth defect(4)if either parent or a close relative has an inherited disease or birth defect(5)if either parent already has children with birth defects or genetic disorders,(6)if the mother-to-be has had two or more miscarriages or babies that died in infancy(7)if the mother-to-be will be 35 or older when the baby is born,Chances of having a child with Down syndrome increase with the mothers age:a 35-year-old woman has a one in 350 chance of conceiving a child with Down syndrome.This chance increases to one in 110 by age 40 and one in 30 by age 45.,(8)if parents are concerned about genetic defects that occur frequently in their ethnic or racial group,For example,couples of African descent are most at risk for having a child with sickle cell anemia;couples of central or eastern European Jewish(Ashekenazi),Cajun,or Irishdescent may be carriers of Tay-Sachs disease;and couples of Italian,Greek,or Middle Eastern descent may carry the gene for thalassemia,a red blood cell disorder.,3.What to Expect During a Visit,Before he meet with a genetic counselor in person,youll be asked to gather information about his family history.,The counselor will want to know of any relatives with genetic disorders,multiple miscarriages,and early or unexplained deaths.,The counselor will also want to look over his medical records,including any ultrasounds,prenatal test results,past pregnancies,and medications he may have taken before or during pregnancy.,If more tests are necessary,the counselor will help him set up those appointments and track the paperwork.When the results come in,the counselor will call him with the news.Often,the counselor will encourage him to come in for a discussion.,The counselor will study his records before meeting with him,so he can make the best use of his time together.During his session,he or she will go over any gaps or potential problem areas in his family or medical history.,The counselor can then help him understand the inheritance patterns of any potential disorders and help assess his chances of having a child with those disorders.,He or she will distinguish between risks that every pregnancy faces and risks that he personally faces.Even if he discovers he has a particular problem gene,science cant always predict the severity of the related disease.For instance,a child with cystic fibrosis can have debilitating lung problems or,less commonly,milder respiratory symptoms.,4.After Counseling,He and his family will have to decide what to do next.Genetic counselors help him to understand his options and adjust to the difficulties and uncertainties he faces.,If he has learned prior to conception that he and/or his partner are at high risk for having a child with a severe or fatal defect,his options might include:pre-implantation diagnosisusing donor sperm or donor eggs adoption,If he has received a prenatal diagnosis of a severe or fatal defect,his options might include:preparing himself for the challenges youll face when he have your baby fetal surgery to repair the defect before birth ending the pregnancy,For some families,knowing that theyll have an infant with a severe or fatal genetic condition seems too much to bear.Other families are able to adapt to the news-and to the birth-remarkably well.,Genetic counselors can share the experiences theyve had with other families in your situation.But they will not suggest a particular course of action.,A good genetic counselor understands that what is right for one family may not be right for another.,Genetic counselors can,however,refer he to specialists for further help.For instance,many babies with Down syndrome are born with heart defects.,The counselor might encourage him to meet with a cardiologist to discuss heart surgery,and a neonatologist to discuss the care of a post-operative newborn.,Genetic counselors can also refer he to social workers,support groups,or mental health professionals to help he adjust to and prepare for your complex new reality.,