Down Syndrome : A Congenital Disorder Arising From A Chromosome Defect

1402 WordsNov 28, 20156 Pages
Down syndrome is a congenital disorder arising from a chromosome defect, the chromosome causing the problems is Chromosome 21. Down syndrome current affect about 1 in 600-800 live births in the United States. There are about 400,000 Americans that have Down syndrome, with approximately 6,000 babies are born with this disorder each year. The disorder is thought to form during gametogenesis, during fertilization, or soon after fertilization (Daniilidis, et al. 2015). Fertilization occurs when the sperm binds to zona pellucida, then the sperm undergoes acrosome reactions which will lyses a hole in zona pellucida, and then the sperm and egg membrane fuse. Once the membranes fuse, the sperms genetic material gets released and gets combined with the egg’s chromosomes, thus resulting in a 46 chromosome fertilized egg. This is the mostly likely phase in which Down syndrome gets formed, since it is caused by a mistake in cell division during the development of the egg, sperm or embryo. The mother or the father can be the origin in which the extra partial or full chromosomes come from, but approximately only 5% have been traced to the father. Maternal age is the only risk factor that has been linked to an increased chance of Down syndrome. Down syndrome is not inherited, but 4% of translocation Down syndrome is inherited (Mayo Clinic Staff). Down syndrome is characterized by three different types: trisomy 21 (nondisjunction), translocation, and mosaicism. The cause of Trisomy 21 is
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