Q.Mangolism is a genetic disorder which is caused by the presence of an extra chromosome number

Down's syndrome (trisomy 21) is caused by an extra copy of chromosome 21 — three copies instead of the normal homologous pair — most often arising from non-disjunction during meiosis. It is one of the most clinically recognisable chromosomal disorders, characterised by severe mental retardation, defective development of the central nervous system, increased separation between the eyes, a flattened nasal bridge, malformed ears, and a mouth that stays constantly open with the to …