Description and Benefits
A number of genetic disorders occur more frequently in Ashkenazi Jewish population. These genetic disorders are inherited in an autosomal recessive fashion, meaning that two copies of the gene (alleles) from parents should be inherited in one child in order to have the disease. In this sense screening the general population is quite beneficial in learning about mutations carried in each individual. If both parents are carriers for a certain genetic disorder then through genetic counseling and genetic analysis they could have a disease free family.
Prevalence It is estimated that as often as 1in 4 or 1in 5 of Ashkenazi Jews would be a carrier for one or more of the common genetic disorders. Hence carrier genetic screening would be a useful tool in deciphering the mutations and taking the most appropriate steps to minimize the effects.
Currently we test for 12 +1 (Cystic Fibrosis upon request) genetic disorders that are prevalent in Ashkenazi Jewish population, they include:
Bloom syndrome is caused by mutations in the BLM gene, which is important in maintaining the stability of the DNA for correct DNA replication during cell division. Symptoms are small body size and redness of face aggravated by sun exposure (erythema or butterfly rash). Carrier Frequency: 1/100.
Canavan Disease is caused by mutations in ASPA gene, which is important in functional nerve impulses and transmission. Symptoms are mental retardation, loss of previously acquired motor skills, abnormal muscle tone (floppiness), poor head control and megacephalus or abnormally enlarged head. Carrier Frequency: 1/40.
Familial Dysautonemia is caused by a mutation in a protein called IKAP gene, which affects the development and survival of sensory neurons in the autonomic and sensory nervous system. Common symptoms include insensitivity to pain, poor growth, inability to produce tears, and labile blood pressure. Carrier Frequency: 1/30.
Fanconi Anemia Type C is caused by mutations in genes of FANC family, which affects the white and red blood cells, as well as the platelets. Symptoms include Short stature, skeletal anomalies, increased incidence of solid tumors and leukemia, and bone marrow failure (aplastic anemia). Carrier Frequency: 1/90.
Mucolipoidosis Type IV is caused by mutations in TRPML1 gene, which affect the body's ability to carry out the normal turnover of various materials within cells. Symptoms include mild learning disabilities to severe mental retardation and skeletal deformities, delayed psychomotor development. Carrier Frequency: 1/90.
Neimann-Pick disease is caused by mutations in the SMPD1 gene, which affects lipid metabolism causing harmful amounts of lipids to accumulate in the spleen, liver, lungs, bone marrow, and brain. Symptoms include enlarged liver and spleen, progressive deterioration of the nervous system, blood abnormalities such as abnormal cholesterol and lipid levels. Carrier Frequency: 1/75.
Tay-Sachs disease is caused by mutations in HEXA gene resulting in accumulation of harmful quantities of a fatty acid derivative in the nerve cells of the brain. Symptoms include Seizures, noticeable behavior changes such as the infant stops smiling, crawling or rolling over, increased startle reaction, decreased eye contact, slow body growth with increasing head size. Carrier Frequency: 1/30.
Gaucher Disease Type I is caused by a deficiency of the enzyme glucocerebrosidase, leading to accumulation of a fatty substance in the spleen, liver, kidneys, lungs, brain and bone marrow. Symptoms include enlarged spleen and liver, liver malfunction, skeletal disorders and bone lesions, severe neurological complications, and swelling of lymph nodes. Carrier Frequency: 1/15.
Glycogen Storage Type Ia is due to glucose-6-phosphatase deficiency resulting in glycogen accumulation in tissues, which causes clinically significant end-organ disease with significant morbidity. Common symptoms include hypoglycemia, active seizures, specifically hypoglycemic seizures. Carrier Frequency: 1/60.
Maple Syrup Urine Disease is caused by mutations in BCKDH gene leading to a buildup of some amino acids and their toxic by-products in the blood and urine. Symptoms include sweet-smelling urine, with an odor similar to that of maple syrup, poor feeding, vomiting, dehydration, seizures, and ketoacidosis. Carrier Frequency: 1/80.
Hemophilia C is caused by mutations in coagulation factor XI resulting in non-stop bleedings. Symptoms include prolonged bleeding from injuries, frequent or heavy nosebleeds and menstrual bleedings, traces of blood in the urine. Carrier Frequency: 1/8 to 1/10.
Familial Adenomatous Polyposis is a caused by mutations in APC gene resulting in cellular overgrowth that leads to the formation of hundreds to thousands of polyps, which if not treated can become cancerous in colon. Symptoms include trances of blood in stool. Carrier Frequency: 1/15.