As read in my previous article; genetic mutation, you should know that chromosome mutation is an error in cell division. By this we mean that during cell division the chromosomes in any one pair do not divide and remain intact. This results in one daughter cell lacking chromosome in its one pair while the other has one extra chromosome in one of its pair. This error is called chromosome mutation and results in abnormality.
One common example is the Down’s Syndrome. In this disease, during meiosis the chromosome do not divide and the pair 21 has one extra chromosome. The egg formed from meiosis has the abnormal chromosome number. When it is fertilized with a normal sperm, it results in a zygote having 47 chromosome number rather than 46 (the diploid number of chromosomes in human cells). The offspring born from this is abnormal; it has slow growth rate, facial features indicating abnormality, and low to moderate intelligence. The mutation is common in older woman who fail to produce a normal egg. This means a younger woman has a 1 in 1500 chance of producing an offspring with Down’s Syndrome while in old woman it is 1 in 100 chance that the offspring produced has Down’s Syndrome. The offspring born with Down’s Syndrome may not survive but with proper treatment and medications the child will survive and live for a long lifespan.