الفهرس 
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Abstract
DS is the most common autosomal abnormality. The frequency is about one case in 600 live births.
Studies done in Egypt revealed that the prevalence of DS varies between 1 in 770 live birth in one study, to 1 in 1000 in another study.
It is estimated that about 95% of individuals with DS have an extra chromosome 21 as a result of meiotic non disjunction, the extra copy of chromosome 21present in all the cells of the baby and in these cases the condition is referred to as trisomy 21.
There are many anomalies associated with DS. The most common anomalies include intellectual impairment, heart disease, GIT anomalies. Heart disease is the main factor affecting the course of DS. Among all cases of congenital heart disease, 4%-10% are associated with Down Syndrome, and 40%-60% of Down Syndrome patients present with congenital heart diseases. Cardiac malformation is the principal cause of mortality in the first two years of life of DS cases.
The most frequent cardiac anomalies seen in DS patients are atrioventricular septal defects (AVSD) which affect the mortality rate of DS. Other CHDs are patent ductus arteriosus (PDA), tetralogy of Fallot (TOF), and valve insufficiency. Many DS children present with more than one type of CHD. It was reported that CHD increase the mortality in Down Syndrome patients by 28%. The aim of the present work was to investigate the association between different potential risk factors and congenital heart defects associated with Down Syndrome in the last 10 years (from 2006-2015) in Alexandria, Egypt and to study the distribution and determinants of other congenital birth defects among children with Down Syndrome.
Our case control study included 560 DS patients, we collected the records of 400 DS patient with cardiac defects and 160 DS without cardiac defects, from Genetic clinics in Medical Research institute and in Elshatby hospital. We studied different risk factors among both groups.
Results of the present study revealed that the most common cardiac defects associated with DS, were, ASD which was present in 35% of studied DS casesfollowed by PFO, PDA, VSD, and AVSD (17%,15%,14%,7 % respectively).Isolated defects constituted 55%, while combined defect were about 45% of cases with CHD.
The logistic regression model predicting cardiac defects revealed that sex and karyotype were significant predictors while adjusting for other factors (R2=35%, female gender (OR: 1.57, CI: 1.08 to 2.2), non disjunction karyotype (OR: 3.6, IC: 2 to 9.4).
There was an increase in the number of cardiac anomalies in DS patients in the (2009-2011) years (to reach 80.8%) then gradual decline to reach 70.7% in the last year.
Summary & Conclusion
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In conclusion: the present work demonstrated that:
Down Syndrome is a growing problem. The most common DS associated anomalies are cardiac anomalies.
The most common cardiac defect associated with DS is ASD followed by PFO, PDA, VSD.
Isolated cardiac defects are more common than combined multiple defects
Male sex is a major risk factor in developing cardiac anomalies.
Non disjunction karyotype is more associated with cardiac anomalies among Down cases.
The trend of cardiac defects among DS children, is somewhat stable, it slightly increasedfrom (2009-2011) then gradually declined from (2012-201