In this paper we studied all cases referred as DS from January, 1996 to December, 2003. It was noticed that the number of DS cytogenetically confirmed cases is steadily increasing every year with an abrupt increase after 1999. The same is true for the number of falsely clinically suspected cases which started to increase after 1999, figure(1).

This may be attributed to the parallel increase in the governmental care and awareness of the handicapped children and those with special educational needs to the extent that DS phenotype became a phobia and many parents and physicians over react by referring normal babies for karyotyping to exclude DS.

Figure (1): Cases referred as DS from 1996 to 2003

On the other hand, this was not true for prenatal diagnosed cases, in which the number of cases was the same all through these years (only 1.56%). The same occurred in the first trimester screening and the triple test and is further confirmed by the very small percentage of prenatally diagnosed cases, reflecting an individual referral from special private sector.

Diagnosis in the neonatal period was done in 37.7 % of cases, 69.7 % were diagnosed in the first 6 months and 83.9 % were diagnosed in the first year of life. Early recognition of different kinds of chromosomal abnormalities in DS is important for proper genetic counseling. Against what is expected, most of the adult referred cases of DS in our study were not mosaics; instead, the cause of referral was premarital genetic counseling for his or her brother or sister or another member in the family.