Diseases

About The Diseases

Alpha-1 antitrypsin (AAT) deficiency leads to lung damage and emphysema by the third or fourth decade of life. Liver disease may occur in the first few months of life. The condition is worsened by smoking. A replacement therapy is available but in chronically short supply, and it is not known how effective this is once disease has developed or which people would benefit most. You should consider carrier screening if you have a family history of the disease.

Celiac disease is the most common genetic disease in Europe affecting, for example, about one in 250 people in Italy and one in 300 in Ireland. In celiac disease, a protein called gluten (found in grains) provokes the body's immune system to destroy the small intestine's nutrient-absorbing villi. This destruction leads to malnourishment, but with a gluten-free diet, the villi heal. A gluten-free diet means avoiding all foods that contain wheat, rye, barley, and possibly oats--in other words, most grain, pasta, cereal and many processed foods. Despite these restrictions, people with celiac disease can eat a well-balanced diet with a variety of foods, including bread and pasta. For example, instead of wheat flour, people can use potato, rice, soy or bean flour. Or, they can buy gluten-free bread, pasta and other products from special food companies. The disease is believed to be underdiagnosed in the U.S., where the time between the first symptoms and diagnosis averages about 10 years. Children of a person with celiac disease have about a five to 10 percent chance of developing the disease. You may want to consider screening for yourself or a child if a close relative has celiac disease or symptoms such as anemia, delayed growth or weight loss appear. There is an increased incidence of celiac disease in individuals with Down syndrome.

Congenital adrenal hyperplasia (CAH) is caused by insufficient production of an essential chemical called cortisol. Children with CAH may have male features, such as excess facial hair, and tend to stop growing early and have trouble fighting infections and retaining salt. Girls with the severe form of the condition may have genital defects. The mild form has similar, but less pronounced, symptoms and may go undiagnosed. You may want to consider screening if you have a family history of the disease. During pregnancy, treating the mother can prevent the severe manifestations of CAH.

Cystic fibrosis is characterized by the production of thick mucus, leading to pulmonary and digestive problems. The disease is caused by a mutated CFTR gene (cystic fibrosis transmembrane regulator). About one in 25 Caucasian Americans is a carrier of a mutation in this gene. Cystic fibrosis occurs most frequently in Caucasians of northern European origin. Because there are many possible disease-causing mutations in the gene, most tests are only about 80 to 85 percent accurate and this may be lower in some ethnic groups. Tests for Ashkenazi Jewish carriers are 97 percent accurate, however, because there are three specific mutations in this population for this condition.

Fragile X syndrome is an X-linked recessive disorder that is the leading cause of genetically inherited mental retardation. Because the mutation (in a gene called FMR-1) is X-linked, boys are affected more frequently and more severely; often women are carriers with no or less severe symptoms, however, females can be affected. The mutation consists of segments of unstable DNA that are repeated; the repeats lengthen with each succeeding generation, leading to greater impairment in offspring. Consider carrier screening if you have a family history of Fragile X or mental retardation in male relatives.

Hemophilia A and B are X-linked recessive disorders characterized by low levels or absence of one of two essential blood-clotting proteins. About 20,000 males suffer from hemophilia, with hemophilia A accounting for 85 percent of cases. Treatment with the clotting proteins is expensive. Consider carrier testing if you have a family history of hemophilia or excessive bleeding.

Phenylketonuria, or PKU, is characterized by an inability to metabolize an amino acid called phenylalanine. Buildup of the chemical causes mental retardation, but state-mandated screening programs are able to identify newborns with PKU so that a special phenylalanine-free diet can be started to prevent retardation and other problems. If you were diagnosed with PKU as a child, a special diet is called for during pregnancy. You should consider carrier screening if you have a family history of the disease.

Sickle cell disease is a blood disorder caused by a mutation in the gene that expresses the hemoglobin protein. The disease is characterized by anemia and periodic episodes of pain. Hemoglobin, the substances that carries oxygen in red blood cells, forms uncharacteristic, rodlike clusters in the cells, giving them a sickle shape and impeding their passage in small blood vessels. The cells create a bottleneck that deprives tissues of oxygen and causes pain. The cells die more quickly than normal red blood cells, leaving the body chronically short of such cells and anemic. About one in 12 African Americans is a carrier.

Thalassemia is a term that covers a range of related anemias that vary in severity. A baby with thalassemia major may appear normal during the first year but subsequently develops symptoms such as jaundice (yellowed skin) and low appetite. If untreated, enlargement of the liver and spleen can occur, sometimes leading to heart failure or heightened susceptibility to life-threatening infections.

Von Hippel-Lindau disease (VHL) is a rare, genetic multi-system disorder characterized by the abnormal growth of tumors in certain parts of the body (angiomatosis). The tumors of the central nervous system (CNS) are benign and are comprised of a nest of blood vessels and are called hemangioblastomas (or angiomas in the eye). Hemangioblastomas may develop in the brain, the retina of the eyes, and other areas of the nervous system. Other types of tumors develop in the adrenal glands, the kidneys or the pancreas. Gene testing is available.

Recessive Genetic Conditions More Prevalent in Individuals of Ashkenazi Jewish Descent

Canavan disease is a neurodegenerative disease characterized by lack of the aspartoacylase enzyme, which is critical for central nervous system development and function. The progression is similar to Tay-Sachs disease, and affected children usually die by age five. Your doctor, even an ob/gyn, may not be aware of the risk for Canavan disease. The carrier rate is about one in 40 among Ashkenazi Jews.

Congenital deafness can be caused by one of two changes in a gene called Connexin 26. About one in 21 individuals of Ashkenazi Jewish descent has one of the two mutations.