histological study of height of epithelium, distribution of Goblet cells and thickness of basement membrane in nasal cavity

A retrospective study of chromosomal changes in mentally retarded individuals was carried out at the Armed Forces Institute of Pathology, Rawalpindi from Jan 1988 to April 1993. Cases were referred mainly with the history of mental retardation and delayed milestones while some were referred with dysmorphic features. A total of 526 cases were studied. Ages of the patients ranged between 3 days to 25 years, with a male to female ratio of 2:1. Most of these patients [78%] were the product of consanguinous marriages. The technique of 72 hours lymphocyte culture with Giemsa banding was used for chromosomal studies. Out of the 526 cases, 144 [27.4%] showed chromosomal aberrations. Majority [128/144] of the cases were Down's syndrome, while 8 cases of Fragile X syndrome, 3 cases of trisomy 18, 2 cases of trisomy 13 and 3 cases were diagnosed as Prader- Willi syndrome [del 15q]. Out of 128 cases of Down's syndrome, 85 were the product of consanguineous marriages, parents of 33 cases being first cousins. The mean age of the mothers of Down's syndrome cases was 29.9 years. Number of mosaic Down's syndrome was significantly higher [27%] in our cases than reported in the Western studies. We compared the relationship of the type of Down's syndrome with consanguinity and found that the classical Down's syndrome with severe phenotype was significantly higher in the off springs of consanguineous marriages than unrelated marriages. Although the above data are institutional based, but these do highlight the fact that mental retardation due to chromosomal defects is not uncommon in our population and that the prenatal diagnosis could be a useful method in the control and prevention of such cases