Last week, I explained that most individuals have 22 pairs of autosomal chromosomes and 1 pair of sex chromosomes (for a total of 46 chromosomes all together). But a subset of people has chromosomal abnormalities in the form of an extra chromosome or a missing chromosome. Most chromosome abnormalities are fatal and result in early miscarriages, but some abnormalities are survivable. One of the most common survivable chromosome abnormalities is Down syndrome, in which there are three copies of chromosome 21 instead of two (known as a trisomy). The extra chromosome copy causes physical, mental, and developmental abnormalities. There are…
Comments closed