Out of all the 22 pair of autosomal chromosomes that each and every human being possesses at the time of their birth apart from sex chromosomes, what if one of the chromosome from any one of the pair goes missing? What if one chromosome is added extra? What is the fundamental mechanism that takes place behind this mutation? What leads to the causes and symptoms of these underlying genetical disorders? This book answers all the questions in today's parent's frantic life cycle that mostly opt for a late pregnancy which might lead to the birth of a genetically abnormal child. Trisomy 21 also called as Down syndrome is one of the frequently occurring genetic disorders (birth ratio 1:800) for parent's age greater than 35, which you can learn about in details offered in this book.