Have you ever heard someone talk about their birthmark and been curious to know if you had one? Maybe you had one or even knew someone who had one, but wondered how they were able to get one. The correct way to refer to one of these marks on the human body is not a birthmark, but is actually a defect that someone is born with and is considered a birth defect. “Congenital defects are structural or functional anomalies present at birth that cause physical or mental disability. They are the leading cause of death for newborns during the first year of life. (Cuhna, John F.)” About three percent of children in the United States are born with a birth defect, ranging from small marks on the body to major body defects, which also cause about twenty percent of infant deaths. (Cuhna, John F.) In this article what are birth defects, how do you get them and the main causes of birth defects will be the main factors. Birth defects are caused by three factors; chromosomal abnormalities, single gene defects and multifactorial influences. During conception the fetus receives its genetic makeup, congenital defects resulting from genetic causes are usually caused during fertilization. For the congenital defect to occur, these four procedures could have taken place: chromosomal abnormalities, large-scale duplication, deletions of chromosomal segments or entire chromosomes. (Lobo, Ingrid, Ph.D. and Kira Zhaurova, MS) Single gene defects are in most cases hereditary, unlike chromosomal abnormalities which are caused by genetics. Phenylketnouria (PKU) is a disease commonly known to be hereditary. Single gene defects can also be common within different racial and ethnic groups. Take sickle cell anemia for example,...... middle of paper......14..Cunha, John F., DO. FACOE. "Congenital defects: discover the causes." MedicineNet. NP, 15 April 2014. Network. 9 May 2014. "Data and statistics". Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, July 15, 2013. Web. May 9, 2014. Lobo, Ingrid, Ph.D., and Kira Zhaurova, M.S. “Birth Defects: Causes and Statistics.” Nature.com.Nature Publishing Group, 2008. Web. 09 May 2014. “Overview of Birth Defects.” King's Daughters Health System Children's Hospital. King's Daughter Children's Hospital, June 23, 2013. Web. May 9, 2014. https://www.chkd.org/HealthLibrary/content.aspx?pageid=P02113