THE TYPES OF DOWN SYNDROME
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2017-03-11
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Abstract
Down Syndrome (DS), also known as Trisomy 21 is one of the most common genetic disorders in which there is an extra copy of chromosome 21. DS occurs in about 1 to 650-1000 live births and it can be caused by three types of chromosomal abnormalities: Non-disjunction, Translocation and Mosaicism. The aim of this study is to determine the percentage for each type of DS among patients who participated in the Academic Learning Grant (ALG) from October 2015 to November 2016. This is a descriptive cross-sectional study. Purposive sampling technique was used for this research. The sample for this research is secondary data of DS individual who were diagnosed through ALG program from October 2015 to November 2016. The sample for this research is 75 individuals suspected of DS who have given their blood for karyotype testing, however 5 samples were later excluded as the karyotype results either showed other chromosomal abbreviation than that of trisomy 21 or were normal or the blood sample failed to be cultured. The results of this study shows that the valid total of 70 samples, 67 samples (95.71%) were Non-disjunction DS and 3 samples (4.29%) with Mosaicism. The overall mele:female ratio of DS samples was found to be 1.92:1. In conclusion, of the 70 confirmed cases of DS, Non-disjunction was diagnosed in the majority of the samples (95.71%) similar with other cytogenetic studies on DS worldwide. However, for this research Translocation DS was not reported and the percentage of Mosaic DS was slightly higher than other researches. Advanced maternal age was found to not be the main risk factor for this study, but other external factors
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Down Syndrome, chromosome 21, karyotype