Cystic Fibrosis:
 Cystic Fibrosis, is a disease caused by an inherited genetic defect. It is not contagious and there is no risk of "catching" CF from another person with CF. About 1 in 23 people in the United States carry at least one defective gene, which makes it the most common genetic defect of its severity in the United States.
 For many years the causes of Cystic Fibrosis was a mystery. Today, recent advances in biology have made the cause more clear. Humans have a gene in their DNA which sends a special protein called CFTR. This protein controls the flow of chloride ions across the cell membrane. Each gene is made up of two alleles; a single correctly encoded allele is adequate for normal CFTR production. Thus it is only when a person has two defective CFTR alleles that they actually have Cystic Fibrosis. Those with a single defective allele are carriers, and those with two defective alleles have Cystic Fibrosis.
 People with Cystic Fibrosis suffer from chronic lung problems and digestive disorders. The lungs of people with Cystic Fibrosis become covered with a sticky mucus which is hard to remove and breeds infection by bacteria. Many people with CF require frequent visits to the hospital and continuous use of antibiotics, enzyme supplements, and other medications. The life expectancy of people with Cystic Fibrosis used to be very short; 30 years ago the median life expectancy was about 8 years. Today, thanks to medical advances, the life expectancy is just under 30 years. There are approximately 40,000 people in the United States with Cystic Fibrosis.

Tay-Sachs Disease
 Symptoms of classical Tay-Sachs disease, an inherited birth defect, first appear at 4 to 6 months of age when an apparently healthy baby gradually stops smiling, crawling or turning over, loses its ability to grasp or reach out, and eventually becomes blind, paralyzed and unaware of its surroundings. Death occurs by age 5.
 Babies with Tay-Sachs lack an enzyme (protein) called hexosaminidase A (hex A) necessary for breaking down certain fatty substances in brain and nerve cells. These substances build up and gradually destroy brain and nerve cells, until the entire central nervous system stops working.
 Both infannt and adult forms of Tay-Sachs disease occur most frequently in descendants of Central and Eastern European Jews. About one out of every 30 American Jews carries the Tay-Sachs gene. Some non-Jewish individuals of French-Canadian ancestry, and members of the Cajun population in Louisiana, are at similarly increased risk. Both groups have about 100 times the rate of occurrence of other ethnic groups. The juvenile form of Tay-Sachs, however, may not be increased in these groups.
 They Tay-Sachs disease can only be transmitted through heredity. A Tay-Sachs carrier has one normal gene for hex A and one Tay-Sachs gene. The carrier does not have the illness and leads a normal, healthy and full life. However, when two carriers become parents, there is a one-in-four chance that any child they have will inherit a Tay-Sachs gene from each parent and have the disease. There is a one-in-four chance that the child will inherit the normal gene from each parent and be completely free of the disease and the Tay-Sachs gene. There is a two-in-four chance that the child will inherit one of each kind of gene and be a carrier like the parents and free of disease. If only one parent is a carrier, none of their children can have the disease, but each child has a 50-50 chance of inheriting the Tay-Sachs gene and being a carrier.
 Prenatal tests called amniocentesis and vile!us sampling (CVS) can diagnose Tay-Sachs before birth. In amniocentesis, which is usually done between the 15th and 18th week of pregnancy, a needle is inserted into the mother's abdomen to take a sample of fluid that surrounds the fetus. The fluid contains fetal cells that can be examined for the presence of hex A. In CVS, the doctor retrieves a sample of cells either through a thin tube inserted through the vagina and cervix to the placenta or by inserting a needle through the mother's abdomen. The placenta contains cells that are genetically identical to those of the fetus, and these cells are examined for the presence of hex A.
 CVS usually is done between the 10th and 12th week of pregnancy. If prenatal testing shows that hex A is present, the baby will not have Tay-Sachs. If it is missing, he or she will be affected. In unusual cases, DNA-based genetic testing can determine whether the fetus has infantile Tay-Sachs or another hex A deficiency and, possibly, how severely affected the baby will be.
 Other approaches using in vitro fertilization are under investigation, but the safety and accuracy of these methods are as yet uncertain.

Phenylketonuria (PKU)
 PKU, in its classic form, is a rare, inherited metabolic disease that results in mental retardation and other neurological problems when treatment is not started within the first few weeks of life. When a very strict diet is begun early and well-maintained, effected children can expect normal development and a normal life span.
 The disease comes from the absence of a single enzyme (phenylalanine hydroxylase). This enzyme normally changes the amino acid, phenylalanine, to another amino acid, tyrosine. Failure of the conversion to take place results in a buildup of phenylalanine. Through a mechanism that is not well understood, the excess phenylalanine is toxic to the central nervous system and causes the severe problems normally associated with PKU. Not every child has the same degree of enzyme deficiency, however; some have enough enzyme activity that the diet can be quite liberal, while others must have the very strict diet. The nature of the diet for an individual child must be determined by an experienced PKU treatment program.
 There is at least one specialized PKU treatment program in most US states. In some less-populated states, families may need to travel to another nearby state, or the treatment may be coordinated through a state health department. All children with PKU ideally should be followed by a specialized PKU program with monitoring facilities.

Retinitis Pigmentosa

 Retinitis Pigmentosa (RP) is the name given to a group of eye diseases characterised by night blindness and the gradual loss of peripheral vision. RP causes tunnel vision and eventual blindness by affecting the light sensitive photoreceptors in the retina, at the back of the eye. A genetic and degenerative disease affecting over four million people world wide and thousands of Australians, RP is a common form of retinal degeneration (RD). Related conditions include Macular Degeneration, Usher Syndrome, Choroideremia, Leber's Amaurosis and Retinoschisis.
 There is no cure for Retinitis Pigmentosa. Around the world, research is being conducted into possible causes and treatments of RD. From discovering the genes responsible for the various forms of the disease to retinal transplants and artificial retinas, the future is looking brighter.

Spina Bifinda
 Spina Bifida (spy-nuh-bi-fi-duh) is the most frequently occurring permanently disabling birth defect. It affects approximately one out of every 1,000 newborns in the United States. More children are affected by this condition than muscular dystrophy, multiple sclerosis, and cystic fibrosis combined.
 Spina Bifida (myelomeningocele) is a birth defect of the spinal column resulting from the failure of the spine to close properly during the first month of pregnancy. In severe cases, the spinal cord protrudes through the back. Surgery to close the newborn's back is generally performed within 24 hours after birth to minimize the risk of infection and to preserve existing function in the spinal cord.
 For many children born with spina bifida, the initial surgeries are only the beginning. Some children regularly participate in physical therapy to learn mobility skills - the use of crutches, braces or wheelchairs - to achieve
independence. Some children with spina bifida (who also have a history of hydrocephalus experience learning problems. Occupational therapists and early intervention programs help prepare children for school. Some children
learn special techniques to become independent in managing their bladder and bowel problems. Some undergo many surgeries by the age of 18 to straighten their spines, lengthen muscles and to control severe bladder problems.
 Physical disabilities like spina bifida can have profound effects on a child's emotional and social development. However, with appropriate medical and rehabilitative care, people with spina bifida become independent, productive adults. Many spina bifida adults today are college educated professionals in a variety of fields.

Leukemia
 Leukemia is a malignant disease (cancer) of the bone marrow and blood. It is characterized by the uncontrolled growth of blood cells. The common types of leukemia are divided into four categories: myelogenous or lymphocytic, which can be acute or chronic. The terms myelogenous or lymphocytic represents the cell type involved. The four major types of leukemia are: acute or chronic myelogenous and acute or chronic lymphocytic leukemia.
 Acute leukemia is a rapidly progressing disease that results in the accumulation of immature, functionless cells in the marrow and blood. The marrow often can no longer produce enough normal red and white blood cells and platelets. Anemia, a deficiency of red cells, develops in virtually all leukemia patients. The lack of normal white cells impairs the body's ability to fight infections. A shortage of platelets results in bruising and easy bleeding. Chronic leukemia progresses more slowly and permits greater numbers of more mature, functional cells to be made.
 The aim of treatment is to bring about a complete remission. Complete remission means that there is no evidence of the disease. Relapse indicates a return of the cancer cells and return of other signs and symptoms of the disease. For leukemia, a complete remission that lasts five years after treatment is considered to indicate cure.
 Treatment centers are reporting increasing numbers of patients with leukemia in complete remission at least five years after diagnosis of their disease.

Galactosemia
 Galactosemia is a rare hereditary disease leading not only to cirrhosis in infants, but more seriously, to early devastating illness if not diagnosed quickly.
 This disease is caused by elevated levels of galactose (a sugar in milk) in the blood resulting from a deficiency of the liver enzyme required for its metabolism (breakdown). To have the disease, a child must inherit the tendency from both parents. The incidence of the disease is approximately 1:20,000 live births. For each pregnancy, in such a family, there is a 1 in 4 chance a baby will be born with the deficiency. Because of the potential disastrous side effects of late diagnosis, many states have mandatory neonatal screening programs for galactosemia. The disease usually appears in the first days of life following the ingestion of breast milk or formula. Vomiting, liver
enlargement, and jaundice are often the earliest signs of the disease, but bacterial infections (often severe), irritability, failure to gain weight, and diarrhea may also occur. If unrecognized in the newborn period, the disease may produce liver, brain, eye and kidney damage.
 Treatment is based on elimination of galactose from the diet. This may be done in the early neonatal period by stopping breast feeding and by the administration of diets which contain no lactose or galactose, (Nutramigen,
Pregestimil). This diet should be compulsively followed, and continued for years, and possibly for life. The red blood cell levels of galactose or its metabolites (Galactose-l-phosphate) may be used as a monitor to gauge the adherence to the diet and restriction of galactose. It is also recommended that mothers of affected infants be placed on a galactose-free diet during the subsequent pregnancy. This may somewhat modify symptoms present at birth. With early therapy, any liver damage which occurred in the first few days of life will nearly completely heal. Galactosemia should be considered in any jaundiced infant because of beneficial effects of early dietary restriction.

Hypercholesterolemia
 Cholesterol is a waxy substance found only in foods that come from animals.  It is also manufactured by the body in the liver. You need small amounts of cholesterol to make and maintain nerve cells and to manufacture natural hormones.
 When you have too much cholesterol in your bloodstream it is called hypercholesterolemia, or high cholesterol. Hypercholesterolemia increases your risk of heart disease.
 The two most important components of cholesterol are low-density lipoprotein (LDL), the so-called "bad" cholesterol, and high-density lipoprotein (HDL), the "good" cholesterol. The goal of most cholesterol treatment is to decrease the LDL in your blood and to raise the HDL.

Albinism
 The word "albinism" refers to a group of inherited conditions. People with albinism have little or no pigment in the eyes, skin, and hair (or in some cases in the eyes alone). They have inherited from their parents an altered copy of a genes that does not work correctly. The altered gene does not allow the body to make the usual amounts of a pigment called melanin.
 Approximately one in 17,000 people have one of the types of albinism. About 18,000 people in the United States are affected. Albinism affects people from all races. The parents of most children with albinism have normal hair and eye color for their ethnic background, and do not have a family history of albinism
 The eye needs melanin pigment to develop normal vision. People with albinism have impairment of vision because the eye does not have a normal amount of melanin pigment during development. The skin needs pigment for protection from sun damage, and people with albinism often sunburn easily. In tropical areas, many people with albinism who do not protect their skin get skin cancers.
 There are several less common types of albinism which involve other problems also, such as mild problems with blood clotting, or problems with hearing. Albinism may cause social problems, because people with albinism look different from their families, peers, and other members of their ethnic group.
 Growth and development of a child with albinism should be normal and intellectual development is normal. Developmental milestones should be achieved at the expected age. General health of a child and an adult with albinism is normal, and the reduction in melanin pigment in the skin, hair and the eyes should have no effect on the brain, the cardiovascular system, the lungs, the gastrointestinal tract, the genitourinary system, the musculoskeletal system, or the immune system. Life span is normal.

Diabetes Mellitus:
 Diabetes Mellitus is a condition of raised concentration of glucose in the blood as a result of a deficiency in the production and/or action of insulin. Insulin is a hormone made in the pancreas. It enables our muscles and othertissues to take up sugar from the blood, which they need for their activities.
 There are two main types of diabetes, type I and type II. Type I Diabetes is also called, "insulin-dependent diabetes mellitus" (IDDM) or "juvenile-onset diabetes" occurs when very little or no insulin is produced. Insulin must be administered. Type 1 is more common in children and adolescents and accounts for 10% of all people with diabetes. Type II Diabetes is also called "non-insulin-dependent diabetes mellitus& (NIDDM) or "late onset diabetes" occurs when
insulin is produced but not sufficiently. Type 2 mostly affects adults. It can be controlled through diet, oral medication and routine exercise.
 There is no cure for Diabetes, but there is effective treatment. In type 1 , diabetes can be controlled by taking insulin, testing of blood glucose levels, eating healthily and exercising routinely. Without insulin, the person can lapse into a life-threatening coma. With type 2, diabetes is treated through diet, oral medication and exercise. If you know how to take care of yourself, based on good medical advice, you can lead an active healthy life.

Bibliography:

1. Cystic Fibrosis:
http://www.cf-web.org/what-is-cf.html
CF-Web, 1998

2. Tay-Sachs Disease:
http://www.noah.cuny.edu/pregnancy/march_of_dimes/birth_defects/taysachs.html
NOAH Team, 1997

3. PKU:
http://www.wolfenet.com/~kronmal/
National PKU News, 1998

4. Retinitis Pigmentosa:
http://www.netserv.net.au/doonbank/rd.html
Ferris, Deane; 1998

5. Spina Bifida:
http://www.gnofn.org/~sba/
Spina Bifida Association of Greater New Orleans, 1998

6. Leukemia:
http://www.leukemia.org/docs/leuk_rel/fc_leukemia.html
Leukemia Society of America, 1998

7. Galactosemia:
http://www.gastro.com/liverpg/galactos.htm
American Liver Association, 1995

8. Hypercholesterolemia:
http://beWELL.com/hic/cholesterol/
Clinical Reference Systems, 1996

9. Albinism:
http://www.cbc.umn.edu/iac/facts.htm
King, Richard; Summers, Gail; Haefemeyer, James; LeRoy, Bonnie; 1997

10. Diabetes Mellintus:
http://ublib.buffalo.edu/libraries/units/hsl/ref/guides/diabetes.html
Buffalo Health Sciences Library, 1998