Guy-Marcel trisomy of the human chromosome numbered
Guy-Marcel Lilavois Jr Professor Hendricks ENC 1101, Composition 1 14 November 2011 Outline INTRODUCTION Thesis Statement: Although Down syndrome is used as a general term, several forms of this syndrome exist. I. Diagnosis A. Discovery B. Cause II. Types A. Trisomy 21 B. Translocation C. Mosaicism III. Expectations From Therapy CONCLUSION Down syndrome Lot’s of people fail to realize that several forms of Down syndrome exist. “Down syndrome is a set of mental and physical symptoms that result from having an extra copy of Chromosome” (NICHD).
According to Merriam-Webster’s Dictionary, “a congenital condition characterized by moderate to severe mental retardation, slanting eyes, a broad short skull; broad hands with short fingers, and trisomy of the human chromosome numbered 21 —called also Down’s syndrome”. A piece of art, in Aachen, Germany around 1505, seems to portray a person with Down syndrome characteristics. However, it wasn’t until 1866 when “Dr. John Langdon Down, an English doctor working in Surrey, first described the characteristic features of the syndrome” (Selikowitz 26) hence the name Down syndrome.
In 1959, Dr. Jerome Lejeune and some colleagues of his showed that “Down syndrome was associated with an extra chromosome” (Selikowitz 26). When a baby is diagnosed with Down syndrome it means that the “baby has a genetic condition resulting from the presence of one extra chromosome in some or all of his or her millions of cells” (Skallerup 2). “This additional chromosome, because of the genes it contains, causes an excessive amount of certain proteins to be formed in the cell” (Selikowitz 33).
So, a person without Down syndrome is born with 2 sets of the 21st chromosomes while one born with Down syndrome has 3 sets of the 21st causing him or her to have 47 chromosomes instead of the normal 46. Three different types of Down syndrome exist: Trisomy 21 found in 95% of cases, Translocation found in 4% of cases, and Mosaicism found in 1% of cases. Children, with the Trisomy 21 type, have “an extra whole chromosome 21 in every cell of the body…. It results from one of the parents giving two number 21 chromosomes, rather than the usual one, to the child through the egg or sperm” (Selikowitz 37).
Parental age may play part for this type. The next one, Translocation, is caused by “the presence of an extra part, rather than the whole, of chromosome 21” (Selikowitz 39). This happens when “the small top portions of chromosome 21 and another chromosome break off, and the two remaining portions stick to one another at their exposed ends” (Selikowitz 39). So far, the cause for this particular type is unknown but it seems like parental age wouldn’t be a contributor. Finally, we have left the least common of the three types, “Mosaicism”.
With this type, there is “an extra whole chromosome 21 in only a proportion of their body cells. The rest of their cells are normal”. This term is used because “the cells of their body are like a mosaic made up of different pieces, some normal and some with the extra chromosome” (Selikowitz 41). “Intervening early in a child’s life to encourage growth and development” (Skallerup 200) is very important when he or she is diagnosed with Down syndrome. Early intervention programs in the U. S. are available “based on diagnosis alone” (Skallerup 200).
So “when faced with new tasks, individuals with Down syndrome may benefit most from a more implicit and repetitive approach” s (Mosse, Emma et al. 1150). Available with the early intervention program are occupational, physical, and speech therapy. Out of the 3 forms of therapy, speech is most common because “many children with Down syndrome will have delayed speech” (Skallerup 201). According to the journal, Language Skills of Children and Adolescents with Down Syndrome, “A distinction is often drawn between exical and syntactical components of receptive language in Down syndrome, with superior comprehension of vocabulary relative to syntax” (Chapman, et al. 1138). People with Down syndrome may exhibit the same characteristics but not all of them develop the same way, and a lot of that has to do with the different types of Down syndrome that exist. With the proper care and therapy catered to each individual’s circumstance, a person with Down syndrome may experience a much more fulfilling life than previously expected.
Works Cited Chapman, R. , S. E. Schwartz, and E. Kay-Raining Bird. Language Skills of Children and Adolescents with Down Syndrome. I. Comprehension. Journal of Speech and Hearing Research, 34, (1991): 1106-1120. Web. 12 Nov. 2011. s “Down syndrome. ” Merrian-Webster Dictionary App ed. 2011. I-Touch. “Down Syndrome. ” NICHD – The Eunice Kennedy Shriver National Institute of Child Health and Human Development Official Home Page, n. d. Web. 12 Nov. 2011. Mosse, Emma K. Christopher Jarrold, and Karla McGregor. “Evidence For Preserved Novel Word Learning In Down Syndrome Suggests Multiple Routes To Vocabulary Acquisition. ” Journal of Speech, Language ; Hearing Research 54. 4 (2011): 1137-1152. Academic Search Premier. Web. 12 Nov. 2011. Selikowitz, Mark. Down Syndrome. New York: Oxford University Press Inc. , 2008. Print Skallerup, Susan J. Babies with Down Syndrome-A New Parent’s Guide. Maryland: Woodbine House, Inc. , 2008. Print