Human genetics is a young science - 100 years ago the word "gene" was not yet part of the English language, scientists were just beginning to spot chromosomes under the microscope and they did not yet understand the role that chromosomes played in heredity. All in all, the concepts of heredity were a black box!
Of course, 100 years ago many people realized that some diseases "ran in families." For example, it was known that men who have hemophilia, a disease in which blood does not clot properly, tended to have male relatives with the same disease. It was also known that these male relatives were usually on the maternal side of the family. This familial bleeding pattern was recognized even in Biblical times: the Bible recommends that women who have had a maternal uncle or brother affected with bleeding problems should not have their sons circumcised because the circumcision would be more likely to cause to excessive bleeding than in families without affected male relatives.
Other diseases, including muscular dystrophy and Huntington's disease, were also known to run in families 100 years ago, but the inheritance pattern of these diseases was not as obvious as with the pattern of hemophilia. However, despite the understanding that some diseases tended to run in families, the process by which a disease could be transmitted from healthy parents to their children was unclear and awaited further research.
In the early 20th century scientists began the in-depth study of modern genetics. In 1899, three European scientists re-discovered the work of Gregor Mendel, a previously little-known Austrian monk who had described some basic principles of genetics thirty years earlier. Although Mendel's pioneering research in genetics involved plants, scientists soon recognized that genetic principles could also be applied to humans. In 1905, W.C. Farrabee, an anthropologist at Yale University, published a study which described a family with brachydactyly, a dominant genetic disorder in which affected people have very short and stubby fingers. This was the first published scientific report of a genetic disease in humans in which the inheritance pattern was clearly identified and predictable- when a parent had the gene for brachydactyly, on average, half of his or her children also had brachydactyly.
Some scientists wanted to use this type of genetic knowledge to eliminate social problems like poverty and crime. Eugenics, the study of how to improve human qualities through directed breeding practices, was first described in the late 19th century by Francis Galton, a cousin of Charles Darwin. Eugenicists felt that traits like intelligence, criminal behavior, poverty, and artistic ability could be traced to simple dominant or recessive genes. By encouraging people with "good" traits to have more children and encouraging people with "bad" traits to have fewer or no children, eugenicists felt they could rid the world of many social problems.
Eugenics took root in many countries, particularly in the United States and Great Britain. The Eugenics Record Office in Cold Spring Harbor, New York and the Eugenics Education Society in London were formed to collect eugenic data about families and to educate the public about eugenics. Between 1907 and 1930, these organizations were world leaders in eugenics and were supported with money donated by wealthy families.
Some eugenicists were overt racists and some were extremists, but many supporters of eugenics were well-intentioned people who mistakenly thought that eugenic programs were helpful to both eugenically desirable and undesirable families. Not all eugenicists were scientists - politicians, lawyers, bankers, social workers and many other professionals supported eugenic views at one time or another.
Eugenics reached an international level during the 1930's as the dark cloud of Adolf Hitler and the Nazi party cast its shadow over Germany. Hitler and the Nazis tried to rid Germany of identifiable minorities including Jews, gypsies, and mentally incompetent people. The Nazis blamed these people, considered to be "genetically unpure," for the social and economic problems which Germany faced following World War I. Some of the Nazi party's eugenic ideas could be traced to the American and British eugenic movements.
With the rise and fall of the horrors of Nazi Germany, both the public and many scientists rejected mainstream eugenics. However, many scientists and physicians were still interested in using genetic information to help families understand the role the role that heredity plays in diseases and birth defects. As a result of this interest, the first medical genetics clinics opened in the United States in the mid-1940's and early 1950's.
Medical geneticists who worked in the early "hereditary counseling clinics" met with families, examined affected individuals and drew pedigrees in an attempt to help clarify the genetic component of diseases and birth defects. They worked primarily with relatively common diseases and conditions such as sickle cell anemia (a condition in which the red blood cells take on a characteristic sickle shape instead of the smooth biconcave shape normally seen), achondroplasia (a form of dwarfism), and cleft palate. What scientific genetic knowledge was available to medical geneticists at the time? Laboratory tests for genetic diseases were few and far between. Watson and Crick had not yet identified the structure of DNA and would not do so until 1954. The correct number of human chromosomes (46) was not discovered until 1956 and the chromosomal basis of Down syndrome (an extra copy of chromosome 21) was not reported until 1958. Physicians working in the hereditary counseling clinics soon realized that even this limited genetic information could have profound social and psychological effects on patients as well as on parents and other relatives. There was clearly a need for counseling and support services for families with genetic disorders.
In order to describe this complex process of providing counseling and support along with genetic information, Sheldon Reed, a geneticist at the University of Minnesota, coined the expression "genetic counseling" in 1947. Reed described the new field of genetic counseling as a kind of genetic social work. Reed felt that genetic counseling should serve the interests of families. This goal was distinctly different from the goal of eugenics, which was to serve the needs of society. In Reed's view, genetic counselors should be non-directive. In other words, the counselor's values should not be forced on the family. The role of the genetic counselor was "to explain thoroughly what the genetic situation is but the decision must be a personal one between the husband and wife, and theirs alone" (Reed, 1955, p.14).
From the mid 1940's through the mid 1960's, medical genetics and genetic counseling was practiced in only a handful of specialty clinics. Although it was felt to be an important medical specialty, very few families actually received genetic counseling during this time.
The practice of genetic counseling took a giant leap forward in 1967 with the first amniocentesis. Amniocentesis is a procedure which is performed by obstetricians to help identify chromosomal and genetic abnormalities which may be present in fetuses. The scientific basis of amniocentesis is straightforward. The fetus is surrounded by amniotic fluid within the amniotic sac inside the mother's uterus. Floating in the amniotic fluid are cells that have washed off the baby's skin, intestines and urinary tract. Each of these cells contains a complete set of fetal chromosomes. In order to collect these cells for amniocentesis, a long, thin needle is placed through the mother's abdomen (not through the belly button!) and a tablespoon or two of amniotic fluid is removed. The fetal cells are removed from the fluid and cultured in the laboratory. Cells are treated with a chemical which halts the cell division process, followed by treatment with a hypotonic solution which causes cells to swell. The swollen cells are then broken open, often by being dropped in a drop of liquid onto a glass slide. Microscopic analysis of the slide will show the chromosomes which have been released from the cells. The chromosomes can then be counted and analyzed to give a genetic "snapshot" of the developing fetus.
This is a photograph of a karyotype made from a human cell with the normal complement of 46 chromosomes. Compare it to the karyotype made from a Down Syndrome cell--note the extra copy of chromosome 21.
Amniocentesis, while tremendously informative, is not a fool-proof process. It carries risks including potential infection and/or miscarriage. In addition, there are limitations on what amniocentesis can predict about the baby. For these reasons, and others, not every woman wishes to undergo the process. Amniocentesis is usually offered to women who will be age 35 or older when the baby is born because by age 35, the statistical chance that a chromosomal defect may be present in the baby is greater than the risks of amniocentesis. Genetic counseling is recommended for all women who may want amniocentesis to help insure that individuals fully understand the risks and limitations, as well as the benefits, of the process.
Physicians and geneticists soon realized that communicating genetic information required specialized training. In 1969, the first advanced degree program for genetic counseling opened at Sarah Lawrence College in New York. This program was not intended for physicians, but instead awarded a master's degree specifically in genetic counseling. The genetic counselor's training combines genetics, medicine, laboratory work, counseling, social work and ethical analysis.
In 1975, the American Society of Human Genetics adopted the following definition of genetic counseling: Genetic counseling is a communication process which deals with the human problems associated with the occurrence, or the risk of an occurrence, of a genetic disorder in the family. This process involves an attempt by one or more appropriately trained persons to help the individual or family to (1) comprehend the medical facts, including the diagnosis, probable course of the disorder, and the available management; (2) appreciate the way heredity contributes to the disorder, and the risk of recurrence in specified relatives; (3) understand the alternatives for dealing with the risk of occurrence; (4) choose the course of action which seems to them appropriate in view of their risk, their family goals, and their ethical and religious standards, to act in accordance with that decision; and (5) to make the best possible adjustment to the disorder in an affected family member and/or the risk of recurrence of that disorder."
During the last 30 years, the field of genetic counseling has expanded rapidly. The National Society of Genetic Counselors, formed in 1979, currently has over 1300 members. There are now more than 20 graduate training programs for genetic counselors in the United States. The American Board of Genetic Counseling certifies training programs that grant masters degrees in genetic counseling. Graduates of these programs must also pass a certifying examination administered by the Board. Genetic counselors practice in a variety of settings, including hospitals, private offices, laboratories, federal and state government offices, universities, and research units. Patients seeking genetic counseling can be younger, elderly, male or female, pregnant or just thinking about starting a family, affected with a disease, at risk for a disease, or simply curious to learn about the role of genetics in their lives.
Genetic counseling can raise complex ethical questions which often do not have clear and simple answers. For example, a couple may choose to have an abortion if testing has revealed severe fetal abnormalities. However, most doctors do not perform abortions, especially if the pregnancy is past the third month. In addition, relatives and friends may oppose abortion, putting enormous pressure on the couple during a difficult time.
A couple may want an amniocentesis to determine the baby's sex and may want to abort the pregnancy if the baby is not of the desired sex. Many genetic counselors feel this is morally wrong and some critics liken the practice to female genocide. Most genetics clinics will not perform testing solely for sex determination. However, the wishes of the couple may conflict with the counselor's strongly held beliefs of non-directiveness and patient autonomy.
A recent challenge for genetic counselors has been the development of predictive testing for adult-onset disorders including breast cancer and Alzheimer disease. With modern genetic technology, DNA testing can indicate the relative probability that some individuals will develop a genetic disease during the fourth or fifth decade of life. Keep in mind, thought, that predictive tests only determine the probability that someone will develop a genetic disease. They do not predict the actual future. Thus an individual with a 75% chance of developing a particular genetic disease may remain healthy throughout his or her life, while an individual with only 25% probability of disease development may succumb to the disease. In addition, for some diseases (e.g. Alzheimer disease) there are no cures or treatments available regardless of predictability. In situations such as these, the benefit of predictive testing remains open to debate.
As genetic research unearths new information and knowledge, so too will new ethical, medical, social and legal problems arise. Genetic counselors can meet these challenges, helping patients and their families to cope with the effects of genetic disease in their lives.What Happens During A Genetic Counseling Session?
Some genetic counseling sessions are simple, and require only one visit. Other times, multiple sessions are needed to collect additional information, to keep the family updated or to deal with ongoing medical and/or psychosocial problems.
The first step in a genetic counseling session is to determine why the patient or family is seeking genetic counseling and to identify what information they wish to get out of the session. Usually only one or two family members attend a counseling session. Sometimes cousins, in-laws, siblings, and grandparents may come. For genetic counselors, the family is the patient, not just the person affected, or potentially affected, with a genetic disease.
An accurate pedigree is an important part of genetic counseling. A pedigree is used to help make a diagnosis of a genetic disease, to determine a person's risk of developing a genetic disease or to determine the risk of having a child with a genetic disease. At minimum, a pedigree includes first degree relatives (parents and siblings), second degree relatives (aunts and uncles) and third degree relatives (cousins and grandparents). The counselor may ask questions about more distant relatives like great-uncles or second cousins when necessary.
Besides depicting familial relationships, a pedigree also contains vital medical information like birth date, age of death, cause of death, health problems, and results of genetic tests. Obtaining medical records on affected relatives can ensure the medical information is accurate.
Sometimes, a pedigree reveals confidential information that is not necessarily known to all family members, such as which relatives have genetic diseases or may suggest non-paternity (when the husband is not the father of the baby). Insurance companies may use information from the pedigree to deny health or life insurance to a person at risk to develop a genetic disease. Therefore, extreme care must be taken to maintain confidentiality.
Once the pedigree is completed and verified, medical tests may be offered to some relatives. These tests may be specialized genetic tests, like a karyotype (chromosome study) or DNA analysis (to detect gene mutations). The tests may also be more general, such as an X-ray, ultrasound, urine analysis, skin biopsy, or physical examination. The cost of the medical testing is not always covered by insurance companies, making it difficult or impossible for some relatives to have a complete genetic evaluation.
After medical tests are completed and records are collected, the genetic counselor may be able to make a diagnosis, or just as importantly, determine that a person does not have or is not at risk for a genetic disease. The pedigree can also be used to estimate the risk relatives face to develop a genetic disease or have a child with a genetic disease.
Genetic counseling involves more than just communicating complex medical information to families. The biggest challenge of genetic counseling is helping families cope with the emotional, psychological, medical, social and economic consequences of genetic disease.
Patients can react in unexpected ways when they learn their genetic risk status. Some people take the information matter-of- factly. Others react with anger, shock, denial, grief, depression, confusion, and guilt. Treating and caring for people with genetic diseases can be expensive, yet some people may lose their jobs and health insurance because of their risk of developing a genetic disease. Someone diagnosed with a genetic disease may be avoided by other relatives because the relatives don't know what to say or because they don't want to face up to the possibility that they too may develop the same genetic disease. Other people may have a hard time understanding the meaning of risk - a risk of 10% may seem high to one relative but seem low to another relative.
Genetic counselors try to help families cope with the many ramifications of genetic testing. Patients who are having severe psychosocial problems may be referred to psychiatrists, social workers, or counselors. Genetic counselors can also help families who are having problems with insurance companies or employers who may not understand the medical implications of genetic testing.