Genetic counseling is the process of determining the risk you have of passing on an inheritable disease to your baby. Genetic counseling involves a specially trained healthcare professional who identifies families at risk, investigates the problem present in the family, interprets information about the disorder, analyzes inheritance patterns and risks of recurrence, and reviews available options with the family.
Genetic counselors work with people concerned about the risk of an inherited disease. The counselor does not prevent the incidence of a disease in a family, but can help family members assess the risk for certain hereditary diseases and offer guidance. Many couples seek genetic counseling because there is a family history of known genetic disorders, infertility, miscarriage, still births, or early infant mortality. Other reasons for participating in genetic counseling may be the influences of a job or lifestyle that exposes a potential parent to health risks such as radiation, chemicals, or drugs. Any family history of mental retardation can be of concern as is a strong family history of heart disease at an early age. Recent statistics show a 3% chance of delivering a baby with birth defects. An additional 2% chance of having a baby with Down syndrome is present for women in their late thirties and older.
Most couples planning a pregnancy or who are expecting do not 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 you become pregnant, a meeting with a genetic counselor can still be helpful. Robert Resta, a genetic counselor, cites the example of babies born diagnosed with spina bifida before birth. Recent research suggests that delivering a baby with spina bifida via cesarean section (avoiding the trauma of travel through the birth canal) can minimize damage to the baby's spine - and perhaps reduce the likelihood that the child will need a wheelchair.
A healthcare provider or counselor needs information to be able to perform genetic counseling. First, a family history must be supplied. The family history includes information about relatives who have a genetic disease. It also covers birth defects and miscarriage in the family. If a woman is pregnant, it is important to know if she has been exposed to anything harmful at home or work. Information on diagnosis is important. Sometimes, the family must provide medical records. It is key to know the results of any genetic screening tests that have been already been done. After gathering these facts, the counselor can determine the person's risk of developing a genetic disease. He or she can also gauge the chances of passing the disease on to children.
Often, genetic counseling can be done immediately after the information is gathered. In other cases information about relatives is needed. This may require a second visit to the counselor. Sometimes, it is necessary to wait until medical records can be reviewed. A healthcare provider or counselor also may need time to determine the risk.
Genetic counseling starts with a talk about the diagnosis. Next, the outcome for people with the disease is discussed. The prospects for everyone in the family are covered. Then, the talk moves on to risk factors. The counselor should first discuss the size of the risk for the affected individual. This will be compared to risk is for anyone in the population. This helps to put the risk into perspective. The choices a person has for dealing with the risk are discussed. These may include genetic testing, treatment, or family planning.
As a genetic counselor will explain, the risk of inheriting a condition is the same for each child of the same two parents. For instance, if both parents are carriers of a recessive disorder (neither parent has the condition, but they are able to pass on the gene for it), each of their children will have a 25 percent chance of inheriting the disorder, a 50 percent chance of being a carrier but not having the condition, and a 25 percent chance of having neither the disorder nor the gene for it. These risks will be the same for each of the couple's children, no matter how many offspring they have. Some birth defects, however, are thought to result from a combination of genetic and other factors, such as the mother's diet, health, and exposure to environmental influences. These defects include spina bifida and cleft lip and palate. According to the March of Dimes Birth Defects Foundation, these defects are much less likely to happen more than once in a family. The risk of a second child's suffering from one of these problems is estimated at about five percent.
Screening blood tests help identify individuals who carry genes for recessive genetic disorders. Screening tests are usually only done if: the disease is lethal or causes severe handicaps or disabilities; the person is likely to be a carrier due to family pedigree or membership in an at-risk ethnic, geographic or racial group; the disorder can be treated or reproductive options exist
A reliable test is available. Genetic disorders such as Tay-Sachs disease, sickle-cell anemia, and thalassemia meet these criteria, and screening tests are commonly done to identify carriers of these diseases. In addition, screening tests may be done for individuals with family histories of Huntington's disease (a degenerative neurological disease) or hemophilia (a bleeding disorder). Such screening tests can eliminate the need for more invasive tests during a pregnancy.
Another screening test commonly used in the United States in the alpha-fetoprotein (AFP) test. This test is done on a sample of maternal blood around week 16 of a pregnancy. An elevation in the serum AFP level indicates that the fetus may have certain birth defects such as neural tube defects (including spina bifida and anencephaly). If the test yields an elevated result, it may be run again after seven days. If the level is still elevated after repeat testing, additional diagnostic tests (e.g. ultrasound and/or amniocentesis) are done in an attempt to identify the specific birth defect present.
Ultrasound is a noninvasive procedure which uses sound waves to produce a reflected image of the fetus upon a screen. It is used to determine the age and position of the fetus, and the location of the placenta. Ultrasound is also useful in detecting visible birth defects such as spina bifida (a defect in the development of the vertebrae of the spinal column and/or the spinal cord). It is also useful for detecting heart defects, and malformations of the head, face, body, and limbs. This procedure, however, cannot detect biochemical or chromosomal alterations in the fetus.
Amniocentesis is useful in determining genetic and developmental disorders not detectable by ultrasound. This procedure involves the insertion of a needle through the abdomen and into the uterus of a pregnant woman. A sample of amniotic fluid is withdrawn containing skin cells that have been shed by the fetus. The sample is sent to a laboratory where fetal cells contained in the fluid are isolated and grown in order to provide enough genetic material for testing. This takes about 7-14 days. The material is then extracted and treated so that visual examination for defects can be made. For some disorders, like Tay-Sachs disease, the simple presence of a telltale chemical compound in the amniotic fluid is enough to confirm a diagnosis.
Chorionic villus sampling involves the removal of a small amount of tissue directly from the chorionic villi (minute vascular projections of the fetal chorion that combine with maternal uterine tissue to form the placenta). In the laboratory, the chromosomes of the fetal cells are analyzed for number and type. Extra chromosomes, such as are present in Down syndrome, can be identified. Additional laboratory tests can be performed to look for specific disorders and the results are usually available within a week after the sample is taken. The primary benefit of this procedure is that it is usually performed between weeks 10 and 12 of a pregnancy, allowing earlier detection of fetal disorders.
Genetic counseling provides couples with information that can help them make decisions about future pregnancies. It also gives couples additional time to emotionally prepare if a disorder is detected in the fetus. The counselor discusses the results of any testing and informs the couple if a problem is apparent. The doctor or genetic counselor also discusses the treatment options available. Genetic counseling is done in a non-directive way, so that any treatment selected remains the personal choice of the individuals involved. Genetic counseling can provide information essential for family planning and pregnancy management, thus maximizing the chances of a positive outcome.
More information on pregnancy
Pregnancy - Pregnancy is period of time between fertilization of the ovum (conception) and birth, during which mammals carry their developing young in the uterus (see embryo).
Pregnancy signs and symptoms - During pregnancy a woman's body undergoes a number of changes to allow the fetus to develop inside the womb. The symptoms of pregnancy vary from woman to woman.
Pregnancy tests - A pregnancy test is a test of blood or urine used to determine whether a woman is pregnant. There are two types of pregnancy tests - blood and urine tests.
Home pregnancy test - A home pregnancy test measures the presence of the hormone human chorionic gonadotropin (hCG) in your urine. All home pregnancy test kits test your pregnancy on the basis of your urine sample.
Pregnancy stages - There are three stages of pregnancy called trimesters. Each trimester is three months. The word "trimester" comes from a Latin word meaning "three months long."
First trimester of pregnancy - First trimester pregnancy is the early stage of pregnancy from conception to 12 weeks gestation, or about 14 weeks from the first day of the last normal menstrual period (LNMP).
Second trimester of pregnancy - In the second trimester the embryo, now known as a fetus, is recognisable as human in form, but is not developed enough to be viable if born. The second trimester is often called the planning trimester.
Third trimester of pregnancy - The third trimester of pregnancy lasts from 28 weeks after your last menstrual period (LMP) until the birth, which usually occurs between the 38th and 42nd weeks of pregnancy.
Calculating pregnancy due date - The due date is usually computed from the first day of the last regular period. In the calendar, this can be figured by taking that date, subtracting three months, and adding seven days.
Prenatal diagnosis - Prenatal diagnosis is the process of detecting and diagnosing fetal abnormalities before birth. A targeted prenatal diagnosis is done when there is a concrete suspicion that there might be a particular disorder.
Healthy pregnancy diet - A balanced diet is key to having a healthy pregnancy. Pregnancy places substantial demands on the availability of iron in the body.
Nutrition during pregnancy - Nutrition is an essential component of prenatal care. During pregnancy, your body needs more nutrients in order to provide a baby with what it needs. Eat enough food to gain weight at the rate recommended by your health care provider.
Exercise during pregnancy - Exercise plays an important role in promoting health and well-being for pregnant women. Excessive levels of physical activity in pregnancy can reduce fetal growth and increase the risk of preterm delivery.
Spotting during pregnancy - Spotting is light bleeding similar to your period and it can happen at any time during pregnancy, but it is most common during the first trimester.
Bleeding during pregnancy - Bleeding from the vagina in early pregnancy is very common. First trimester bleeding is any vaginal bleeding during the first 3 months of pregnancy.
Smoking during pregnancy - Cigarette smoking during pregnancy can cause serious health problems to an unborn child. Many complications of pregnancy are more likely to occur in smokers.
Sex during pregnancy - Sex and sexual intercourse are not harmful during pregnancy. For most women and their partners, sex during pregnancy is fine as long as both partners consent and are comfortable.
Prenatal care - Prenatal care is the health care that a woman receives before her baby is born. Prenatal care is provided for women during the period between conception and birth of the baby.
Teenage pregnancy - Teenage pregnancy is a pregnancy that occurs in an adolescent. Babies born to teenagers are at risk for neglect and abuse.
Twins and multiple birth - Multiple pregnancies are on the rise in recent years with more and more twins and other types of multiples being born. A multiple birth is when more than one human baby results from a single pregnancy.
Childbirth - Childbirth (also called labour, birth, or parturition) is the culmination of pregnancy, the emergence of a child from its mother's uterus.
Obstetrics - Obstetrics is the surgical specialty dealing with the care of a woman and her offspring during pregnancy, childbirth and the puerperium (the period shortly after birth).
Pregnancy ultrasound - Pregnancy ultrasound is a method of imaging the fetus and the female pelvic organs during pregnancy.
Chinese lunar pregnancy calendar - The Chinese pregnancy calendar was allegedly discovered about 700 years ago. The accuracy of the chart has been proved by thousands of people and is believed to be 99 percent accurate.
Fertility charting - Fertility charting allows you to predict ovulation, pinpoint your most fertile time in your cycle, and increase your chances of becoming pregnant.
Ovulation: calendar, prediction, test - Ovulation is the process of discharging a mature ovum (egg) from an ovary after a Graafian follicle - representing the final stage of follicular development before ovulation - has been formed.
Getting pregnant - The best or most fertile time to get pregnant is the period of ovulation in your menstrual cycle. Most women ovulate (release an egg from the ovary) about two weeks before their period.
Gender selection - There are three main techniques of sex selection: pre-natal testing and termination of pregnancy, pre-implantation genetic testing of embryos, and sperm sorting.
Prenatal tests - Prenatal tests are one of the many ways your practitioner can check on the well-being of your growing baby and find out whether you're at risk for complications.
Genetic screening - Genetic screening is a process used to find out what diseases or birth defects a child might inherit from his or her parents.
Genetic counseling - Genetic counseling is the process of determining the risk you have of passing on an inheritable disease to your baby.
Birth control (contraception, pregnancy prevention) - Birth control is the practice of preventing or reducing the probability of pregnancy without abstaining from sexual intercourse; the term is also sometimes used to include abortion.
Male condoms - Condoms are thin barriers made of latex, plastic, or natural membranes. The male condom fits over a man's penis. The female condom fits inside a woman's vagina.
Female condoms - The female condom is a polyurethane sheath or pouch about 17 cm (6.5 inches) in length. It is worn by a woman during sex.
Diaphragm - A diaphragm is a rubber disc a woman places into her vagina. The diaphragm blocks a man's semen from entering the cervix (the opening to the womb).
Cervical cap - The cervical cap is a small latex cup that a woman inserts into her vagina before sexual intercourse. The cervical cap fits snugly over the woman's cervix.
Birth control pills - The birth control pill is a small, usually white, tablet that is taken orally (by mouth). The pill usually comes in a packet that has days marked off for a cycle lasting about a month.
Norplant - Contraceptive implants (Norplant?) are six match stick size implants inserted into the upper arm. Norplant is a form of progestin that is placed under the skin.
Depo Provera - Depo Provera is a hormone, much like the progesterone a woman produces during the last two weeks of each monthly cycle. Depo-Provera or progesterone stops the woman's ovaries from releasing an egg.
Spermicides - Spermicides are chemicals that make the sperm unable to function. Spermicide can be used alone or with other birth control methods to reduce the risk of pregnancy.
Emergency contraceptive pill - Emergency contraception is the use of certain methods after unprotected intercourse to prevent pregnancy.
Natural family planning - Natural family planning is defined as the understanding and use of the natural phases of fertility and infertility by a couple in order to either achieve or avoid pregnancy.
Intrauterine device (IUD) - An intrauterine device (intra meaning within, and uterine meaning of the uterus), is a birth control device also known as an IUD or a coil.
Birth control patch - The birth control patch is a thin plastic patch (1 3/4 inch square) placed directly on the skin of the woman. It is a hormonal method of contraception obtained by prescription.
Sterilization (vasectomy) - Sterilization is a surgical technique leaving a male or female unable to procreate. It is a method of birth control.
Fertility awareness method (FAM) - Fertility awareness is a means of understanding a woman's reproductive cycle by observing and writing down fertility signs.
Abstinence - Periodic abstinence is a way that sexually active women prevent pregnancy by becoming familiar with their fertility patterns and abstaining from vaginal intercourse on the days they think they could become pregnant.
Pre-eclampsia, eclampsia - Pre-eclampsia is a condition which only occurs during pregnancy. It causes high blood pressure, protein leaks from the kidneys, and other symptoms may develop.
HELLP Syndrome - The HELLP syndrome is a complication of pregnancy featuring a combination of abnormal conditions including emolysis, elevated liver enzymes, and low platelet count.
Intrauterine growth restriction - Intrauterine growth restriction (IUGR) refers to the condition in which a foetus is unable to grow to its genetically determined potential size to a degree that may affect the health of the foetus.
Premature birth - Premature birth is defined medically as a birth occurring earlier than 37 weeks. Infants born prematurely have an increased risk of death in the first year of life.
Stillbirth - Stillbirth refers to the death of a baby after 24 weeks of pregnancy but before birth. A pregnancy that ends before the twentieth week is called a miscarriage rather than a stillbirth.
Caesarean section - A Caesarean section (Cesarean section AE), is a surgical procedure to deliver one or more babies through an incision in the mother's abdomen and uterus.
Preterm labor - Preterm labor, or premature labor, is when the uterus (womb) contracts and the cervix opens earlier than normal.
Rh incompatibility - Rh incompatibility is a condition that occurs when the mother of a fetus or newborn has Rh-negative blood type and the fetus or newborn has Rh-positive blood.
Ectopic pregnancy - An ectopic pregnancy is one in which the fertilized ovum is implanted in any tissue other than the uterine wall.
Pregnancy diabetes (gestational diabetes) - Gestational diabetes is a condition in which the glucose level is elevated and other diabetic symptoms appear during pregnancy in a woman who has not previously been diagnosed with diabetes.
Group B strep - Group B streptococcus (group B strep) is a type of bacteria that causes infection among newborns, pregnant women or women after childbirth.
Morning sickness (NVP) - Morning sickness, also called nausea and vomiting of pregnancy (NVP), affects between 50 and 85 percent of all pregnant women.
Hyperemesis gravidarum - Hyperemesis gravidarum means excessive vomiting during pregnancy. The severe vomiting associated with hyperemesis gravidarum requires medical attention.
Miscarriage (spontaneous abortion) - Miscarriage is the term used for a pregnancy that ends on it's own, within the first 20 weeks of gestation.
Postpartum hemorrhage - Postpartum bleeding (severe postpartum bleeding) is the loss of more than a pint of blood within the first 24 hours after delivering a baby.
Pregnancy-induced hypertension - Pregnancy-induced hypertension (also referred to as toxemia, preeclampsia and eclampsia) is a condition that may develop during the second half of a woman's pregnancy.
Pica - Pica is a pattern of eating non-nutritive substances (such as dirt or paper), lasting for at least one month.