الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Congenital heart disease is the most common type of congenital abnormality affect up to 8 of 1000 newborns. It was hypothesized that these CHD lesions may be the result of interactions between genetic and environmental factors. Significant risk of CHD recurrence was correlated to familial factors with variability of pattern and figures among studies from different populations. The current study included 1960 families with at least one sibling with CHD for estimating the risk of recurrence of CHDs among Egyptian families. The total studied individuals in the study were 66980. In the present study, the commonest phenotypic diagnostic category of index patient was isolated VSD group (25%, 490/1960) followed by isolated ASD group (17.2 %, 337/1960, and RVOT (13.8% ,271/1960) The recurrence risk of CHD in Egyptian families was (6.4%, 126/1960) of the included families with higher recurrence risk in first degree relatives than second- and third-degree relatives. Regarding the pattern of recurrence, the commonest pattern of familial recurrence of CHD in our work was discordant recurrence in 45.4% of recurrent cases followed by exact concordance 42.3% and group concordance 12.3%. The highest recurrence risk ratio was detected in septal defect plus LVOTO, APVR, septal defect plus RVOTO, isolated VSD and LVOTO. With different pattern of recurrence which differ according to type of CHD .VSD, LVOTO, and conotruncal diseases recurrence, display a high degree of exact concordance. while RVOTO and PDA display a high degree of discordant recurrence. In the present study the recurrence risk increases among siblings (27%,36/130) more than when a parent (10.77% ,14/130) is affected. The recurrence risk of CHD was higher if the affected parent was the mother (6.9% ,9/130) rather than father (3.8 % ,5/130). The pattern of recurrence of CHDs among siblings was mostly exact recurrence with (43.3% ,13/30) had the same type of CHD, (36.7% ,11/30) the CHDs were dissimilar, and (20% ,6/30) had similar types of CHD. Regarding twins, the present study showed an increased risk for CHD live-born twins compared with singletons, the estimated recurrence risk among twins was (6/42, 14%). Amongst the 1960 cases of CHD in our study, 343 patients (17.5%) were children of consanguineous marriages. The recurrence of CHD is significantly higher in children with consanguineous parents (p 0.001) in comparison to children with non-consanguineous parents. As far we know no previous study on the effect of consanguinity on the recurrence of CHDs. The overall familial recurrence rate of CHD among Egyptian families is relatively high estimated around 6.4 %, the high risk of recurrence indicates that familial shared factors are substantially important as etiologic element of CHD. Recurrence rates vary by phenotypic category of CHD, however; dissimilar recurrence was the predominant pattern. Furthermore, the highest recurrence rates were among first-degree relatives These finding will hugely impact the counseling process of families with history of CHD in Egypt.