FISH: TRISOMY 21 / DOWN SYNDROME, POSTNATAL

DOWN SYNDROME / TRISOMY 21 IS A GENETIC DISORDER WITH AN EXTRA COPY OF FULL OR PARTIAL CHROMOSOME 21 RESULTING IN DEVELOPMENTAL DELAYS, DISTINCT FACIAL FEATURES & CONGENITAL DEFECTS. ABOUT 95% CASES ARE DUE TO TRISOMY 21; 2% RESULT FROM ROBERTSONIAN TRANSLOCATION; 2% DUE TO MOSAICISM & 1% DUE TO A VARIETY OF CHROMOSOMAL REARRANGEMENTS. THIS IS A POSTNATAL TEST CONDUCTED ON INDIVIDUALS SHOWING FEATURES OF DOWN SYNDROME LIKE HYPOTONIA, SMALL EARS, UPSLANTING PALPEBRAL FISSURES, FLAT FACIAL PROFILE ETC. OR HAVE A FAMILY HISTORY OF DOWN SYNDROME.