Genetic Disorders and Counseling

By: Courtney Coyle, Mary Neville, and Ethan LinvilleMr. Taylor’s 8th Grade Gifted Science ClassApril 2005

Down Syndrome Down Syndrome is a

genetic disorder caused by extra genetic material. It affects over 350,000 people in the United States alone and is the most common imbalance in the number of autosomes in people.

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Causes of Down Syndrome

Down syndrome is the most common form of mental retardation caused by chromosomal aberration. The disease results from having three copies of all or a portion of chromosome 21. The risk of having a liveborn with Down syndrome increases with the mother's age, from 1 in 1000 at age 30 to 9 in 1000 at age 40. Most cases (~95%) of Down syndrome result from the presence of an intact extra copy of chromosome 21; however, translocation of a 1 copy of a critical region of this chromosome to another acrocentric chromosome (most often chromosome 14) can also lead to Down syndrome.

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Diagnosis: Pre-natal

Two types of procedures are available to pregnant women: screening tests and diagnostic tests. The screening tests estimate the risk of the baby having Down syndrome. Diagnostic tests tell whether or not the baby actually has Down syndrome.

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Symptoms Decreased muscle tone at birth Separated sutures (joints between the

bones of the skull) Asymmetrical or odd-shaped skull Round head with flat area at the back of

the head Small skull Upward slanting eyes, unusual for

ethnic group Small mouth with protruding tongue Broad short hands Single crease on the palm Retarded growth and development Delayed mental and social skills (mental

retardation) Iris lesion (an abnormality of the colored

part of the eye called Brush field spots) Source

Effects of Down Syndrome

Many children with Down syndrome have health complications beyond the usual childhood illnesses. Approximately 40% of the children have congenital heart defects. It is very important that an echocardiogram be performed on all newborns with Down syndrome in order to identify any serious cardiac problems that might be present. Some of the heart conditions require surgery while others only require careful monitoring. Children with Down syndrome have a higher incidence of infection, respiratory, vision and hearing problems as well as thyroid and other medical conditions. However, with appropriate medical care most children and adults with Down syndrome can lead healthy lives. The average life expectancy of individuals with Down syndrome is 55 years, with many living into their sixties and seventies.

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How it Affects Everyday Life

Most children with Down syndrome have mild to moderate impairments but it is important to note that they are more like other children than they are different. Early Intervention services should be provided shortly after birth. These services should include physical, speech, and developmental therapies. Most children attend their neighborhood schools, some in regular classes and others in special education classes. Some children have more significant needs and require a more specialized program.

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Treatments There is no specific

treatment for Down syndrome. Special education and training is offered in most communities for mentally handicapped children. Specific heart defects may require surgical correction. The potential for visual problems, hearing loss, and increased susceptibility to infection will require screening and treatment at appropriate intervals.

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Hemophilia Hemophilia is a rare genetic blood

clotting disorder that primarily affects males. People living with hemophilia do not have enough of, or are missing, one of the blood clotting proteins naturally found in blood. Two of the most common forms of hemophilia are A and B. In persons with hemophilia A (also called classical hemophilia), clotting Factor VIII is not present in sufficient amounts or is absent. In persons with hemophilia B (also called Christmas disease), clotting Factor IX is not present in sufficient amounts or is absent. People with hemophilia do not bleed more profusely or bleed faster than normal; they bleed for a longer period of time. Source

Types of Hemophilia hemophilia A - caused by a lack

of the blood clotting factor VIII; approximately 85 percent of hemophiliacs have type A disease.

hemophilia B - caused by a deficiency of factor IX.

von Willebrand disease - a part of the factor VIII molecule known as von Willebrand factor or ristocetin cofactor is reduced. The von Willebrand factor involves helping the platelets (blood cells that control bleeding) attach to the lining of a vein or artery. This missing factor results in prolonged bleeding time because the platelets are unable to attach to the wall of the vessel and form a plug to stop the bleeding. Source

Causes of Hemophilia Hemophilia types A and B are

inherited diseases passed on to children from a gene located on the X chromosome. Females have two X chromosomes, while males have one X and one Y chromosome. A female carrier of hemophilia has the hemophilia gene on one of her X chromosomes. When a hemophilia carrier female is pregnant, there is a 50/50 chance that the hemophilia gene will be passed on. If the gene is passed on to a son, he will have the disease. If the gene is passed on to a daughter, she will be a carrier. If the father has hemophilia but the mother does not carry the hemophilia gene, then none of the sons will have hemophilia disease, but all of the daughters will be carriers.

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Effects of Hemophilia

The most common cause of disability from hemophilia is chronic joint disease, or arthropathy, which is caused by uncontrolled bleeding into the joints.

Hemorrhage, which is a severe internal or external discharge of blood, is a continuing problem

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Symptoms Bruising Bleeds easily Bleeding into a joint Bleeding into the

muscles Bleeding from injury

or bleeding in the brain

Other sources of bleeding

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abnormal

Long-term Effects Hemophilia is a lifelong

disease. With the advances of specific clotting factors in laboratories, prevention and treatment of bleeds is improving.

With careful management, informed decisions, and recognition of complications, many children with hemophilia can live relatively healthy lives with a normal lifespan.

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Treatment Parents may want to purchase soft toys with rounded corners for young

children. Padded clothing and helmets may be necessary for the child that is learning to walk or becoming more active. Contact sports in school should be evaluated for risks of injury to the child.

Immunizations may need to be given under the skin instead of in the muscle to prevent deep muscle bleeds.

Joint hemorrhages may require surgery and/or immobilization. Before surgery, including dental work, your child's physician may

recommend factor replacement infusions to increase the child's clotting levels prior to the procedures.

Your child's physician may also recommend the discontinuation of aspirin, and aspirin-containing products, since these products have been linked to bleeding problems.

Blood transfusions may be necessary if significant blood loss has occurred.

Proper dental hygiene is a preventive measure.

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Genetic Counseling

An educational counseling process for individuals and families who have a genetic disease or who are at risk for such a disease. Genetic counseling is designed to provide patients and their families with information about their condition and help them make informed decisions.

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How Long Does Counseling Take?

Some genetic counseling sessions are simple and require only one visit. Other times, multiple sessions are needed to collect additional information, to update the family or to deal with ongoing medical and/or psychosocial problems.

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Pedigrees and Counseling

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. Source

What Happens During Counseling

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.

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Genetic counselor examining human karyotype

Reactions to Counseling

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. Source

Ways to Cope with Disorders

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.

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Sources Answers Genetic Disorder Corner National Human Genome Research Institute MadSci Network: Genetics National Association for Down Syndrome Down syndrome (Disease) - Detroit, Michigan Hemophilia Galaxy MCG Health System Yale Medical Group Medicine Net The Natural Health Museum

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