Genetic factors are the sole cause of some non-infectious diseases; such genetic diseases are inherited or are caused by mistakes during cell division when gametes are formed (Alters, 2005). Down syndrome is caused by errors during the gamete formation.
Superimposed upon his individual characteristics, each child and adult with Down syndrome has features that he shares with others who have Down syndrome (Selikowitz, 1997). Down syndrome comes about when there is an extra number 21 chromosome, this additional chromosome, because of the gene it contains, causes an excessive amount of certain proteins to be formed in the cell which in return disturbs normal growth in the body of the fetus (Selikowitz, 1997). ‘Chromosome 21’ is the tinniest of the all the human-chromosomes and have about 225 genes. According to statistics, 95% of children with Down syndrome have ‘trisonomy 21’ or an additional chromosome in all their cells, 3-4% have translocation-form of the additional chromosome where the extra-chromosome 21 is connected to one of the different chromosome-pair and around 1-2% of children have mosaic form in which only some cells are trisonomic while the others are normal.
According to Selikowitz, as the fetus develops, the cells of the body do not divide as rapidly as they normally do, and this result in fewer body cells, and, therefore a smaller baby. The baby, having fewer brain cells and a different brain formation, will learn slowly.
A strong argument for the genetic formulation of Alzheimer’s disease stems from its connection with Down syndrome. An extra chromosome 21 exist in persons with Down syndrome; not only do people with Down syndrome begin to develop symptoms of dementia after the age 35, but also the prevalence of Alzheimer’s disease is higher in families with Down syndrome, and vice versa (Eliopoulos, 2004). An altered chromosome 21 causes an abnormal amyloid to be produced.
Alters. S. (2005). Essential Concepts for Healthy Living. New York: Jones & Bartlett Publishers.
Eliopoulos, C. (2004). Gerontology Nursing. New York: Lippincott Williams & Wilkins.
Selikowitz, M (1997). Down Syndrome: The Facts. New York: Ovford University Press.