I. Introduction. 1  The petroleum industry began with the successful drilling of the first commercial oil well in 1859, and the opening of the first refinery two years later to process the crude into kerosene.
The cause of Down syndrome is one of three types of abnormal cell division involving chromosome 21. All three abnormalities result in extra genetic material from chromosome 21, which is responsible for the characteristic features and developmental problems of Down syndrome.
Down syndrome (sometimes spelled âDownâs syndromeâ) is a genetic abnormality. It is the most common single cause of birth defects in the United States (NIH, 2012). This syndrome occurs because of an extra copy of chromosome 21. Your chromosomes contain your genetic material, and any problems with your chromosomes can cause serious physical and mental health problems.