post 5..genetic disorder #2 (Tay-Sachs Disease)

Tay-Sachs Disease
Tay-Sachs disease occurs when the body lacks hexosaminidase A, a protein that helps break down a chemical found in nerve tissue called gangliosides. Without this protein, gangliosides, particularly ganglioside GM2, build up in cells, especially nerve cells in the brain. Tay-Sachs disease is caused by a defective gene on chromosome 15. When both parents carry the defective Tay-Sachs gene, a child has a 25% chance of developing the disease. Tay-Sachs has been classified into infantile, juvenile, and adult forms, depending on the symptoms and when they first appear. Most people with Tay-Sachs have the infantile form. In this form, the nerve damage usually begins while the baby is still in the womb. Symptoms usually appear when the child is 3 to 6 months old. The disease tends to get worse very quickly, and the child usually dies by age 4 or 5. Deafness, Decreased eye contact, blindness Decreased muscle tone (loss of muscle strength), Delayed mental and social skills, Dementia, Increased startle reaction, Irritability, Listlessness, Loss of motor skills, Paralysis or loss of muscle function, Seizures, and Slow growth are affects if this disorder. There is no treatment for Tay-Sachs disease itself, only ways to make the patient more comfortable. It can be prevented by taking tests on the parents before getting pregnant, and looking at family background.



http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002390/