A study of new potential risk factors for Down syndrome in Upper Egypt

Down syndrome is a common chromosomal anomaly causing multiple congenital malformations and mental retardation (MR) in humans. The well-established risk factor, advanced maternal age, was not found in many of the Down syndrome cases in Egypt, while other possible risk factors have not been well studied yet. In view of this, we have conducted the present study to clarify that issue and throw some lights on other potential risk factors in Down syndrome. During this cross sectional study, conducted during the period between March 2006 and Feb 2008, 48 clinically suspected cases of Down syndrome aged between 6 months and 9 years were referred for chromosomal investigation (karyotyping) from the outpatient and inpatient sections of the pediatric department, University Hospitals at the Upper Egyptian governorate Sohag. Chromosomal study was done in those patients after obtaining an informed consent. Twenty apparently healthy children were randomly selected as controls. Statistical study was carried out using logistic regression analysis. Out of the 48 cases of Down syndrome, 45 had free trisomy 21, two were mosaic trisomy 21, and one had translocation. Logistic regression of case-control study of Down syndrome children revealed that the odds ratio of uncle–niece marriages, or second cousin marriages, or parents lived in rural region, or exposure of the parents to drugs or chemicals, or parents education status, or habits (cigarettes/coffee used) of father, or mother not undergone ante-natal scanning as a part of ante-natal care, or mothers with previous abortions were significant when all the variables of that category were used one at a time. Besides the known risk factors, consanguinity, region (rural/urban) of residence of parents, exposure of parents to chemicals, educational status of parents, habits of father, prenatal scanning, and reproductive performance of mother are possible risk factors for Down syndrome.