IntroductionDown syndrome, also known as Down syndrome, is the most common genetically transmitted disorder (1) and is characterized by the presence of 'a part or an entire third of the 21st chromosome (2). Parents of affected people generally do not have Down syndrome(3). Because it is caused by a double chromosome 21 in either parental gamete (4), Down syndrome is a chronic condition. The effects of Down syndrome vary greatly from patient to patient, but in most cases it is a form of mental disability (5). , in fact, the average mental capacities of an affected adult are comparable to those of a child(3)¬. Another common trait is a weak immune system (3). Physical Symptoms The following table (3) (6) provides the percentages of occurrence of some of the other most common physical symptoms. Trait/symptom Per. (%) Trait/symptom Per. (%) Narrow palate 76 Slanted eyes 60 Flat head 74 Distal phalanx of last finger bent 57 Flat nose 68 White spots in iris 56 Separation of toes 68 Heart defects 40 Neurological symptoms The most common neurological symptom is a reduction in intelligence quotient (IQ). Most people with Down syndrome have a mild IQ (around 60), but more significant mental impairments are also diffuse (11). As a result, affected individuals will possess fewer intellectual skills than their peers. The majority of Down cases show better understanding than speech. On the contrary, social relations are normal. Only in 5% of cases is autism linked to Down syndrome, but some form of mental illness has a higher risk of occurring, at 30%. In addition, Alzheimer's disease affects 10% of people who reach the age of 40(11). Sensory symptomsVision-related disorders are likely to occur in half of the affected population. Strabismus and cataracts affect 20%...... middle of paper......y in men with Down syndrome: a case report".Fertil Steril 86 (6): 1765.e1–3.(14 ) Jeffrey S. Dungan &; Sherman Elias (Last revised 2008). “Prenatal Diagnostic Tests”. Merck Home Health Manual. Cochrane Database Syst Rev (3) (16) “Down Syndrome and Other Chromosome Number Abnormalities.” Nelson's Textbook of Pediatrics (19th ed.) Philadelphia: Saunders 17) McCullough, LB (April 2010). ). “Ethical Considerations in First Trimester Down Syndrome Risk Assessment.” Current Opinion in Obstetrics and Gynecology 22(2):135–8(18) Encyclopedia of Religious Controversies in the United States (2nd ed. Santa Barbara, CA: ABC-CLIO p... 278.