Abstract
Varieties of chromosomal diseases are induced by an abnormal number of chromosomes due to non-disjunction at miosis or by its mosaicisms. Others are caused by structural changes such as a break or a deletion of a certain chromosome and by a translocation in a paired one. New concepts, such as small deletion syndromes, contiguous gene syndromes, gene imprinting syndromes, and DNA triplet repeating diseases are also described. Each disease shows its characteristics in patient's language behaviors. Some people with Down's syndrome, for instance, can express easily their mind but some others can not talk at all. Patients with fragile X syndromes show stuttering in their speech. The purpose of the Pediatric Infant Class in Nishitaga hospital (PIC'n) is described. This class is for children with Down's syndrome and their families. It is helpful for them to meet each other and to get information about the disease and their management.
