Chromosomes and Chromosomal Abnormalities
Roughly one in 150 babies in the United States are born with a chromosomal abnormality, according to the March of Dimes. Such abnormalities can result in miscarriage, stillbirth or severe physical and mental defects. To comprehend the severity of these types of abnormalities, one must first understand the function of chromosomes.
Chromosomes are located within every cell of the body and are critical for the body’s survival because they house a person’s genes. There are roughly 20,000 to 25,000 genes in the body. Genes determine traits such eye color, but they also control crucial developmental functions of the body. Humans have a total of 46 chromosomes, 23 pairs each — one pair inherited by one’s mother and the other by one’s father.
Chromosomal disorders result from errors in either the structure or number of chromosomes present in a person. These types of abnormalities occur when there is an error in the development of the sperm or egg before fertilization. While the most common error consists of too few or too many chromosomes, deletions, translocations, inversions or duplications of a chromosome are also a possibility. When an abnormal egg or sperm unites with its normal counterpart, the embryo will end up inheriting that abnormality.
While chromosomal disorders vary in severity, depending on the genes affected, there are a couple of chromosomal abnormalities that oftentimes cause fatality before the baby’s first birthday due to life-threatening complications. What two chromosomal errors are the worst? These disorders are known as trisomy 13 and trisomy 18.