By this time in the year, most Dragons have at least a basic understanding of genes and chromosomes – those long, squiggly things and strings of letters that supposedly make up an entire organism. In freshman year biology, students learn that human body cells have 46 chromosomes in 23 pairs, with each pair containing one from the mother and one from the father. Inside each chromosome is all the genetic information that makes up an organism. Those who took an interest in these squiggles filled with random letters may have gone on to learn more about them and the role they play in our lives.

During the processes of meiosis, chromosomes are normally neatly duplicated and separated without issue. In roughly 5% of cases, however, nondisjunction occurs. This is when sister chromatids duplicate incorrectly, resulting in extra copies of a chromosome, or a missing copy in rarer cases. The extra or missing sections contain vital genetic information that when altered in number can skew protein production, leading to a variety of symptoms. Usually, the larger the area of the affected chromosome, the more severe the anomaly. Errors of larger chromosomes usually have more severe effects than those of smaller chromosomes (such as 21). Abnormalities of the sex chromosomes usually only have mild effects, although this isn’t always the case. 

One of the most common results of nondisjunction is trisomy, or three copies of a chromosome instead of a pair. The most common trisomies are Trisomy 21 (Down syndrome), Trisomy 18 (Edwards’ syndrome), Trisomy 13 (Patau syndrome), and extra copies of the sex chromosomes (X/Y). Rarer trisomies include Trisomy 8, 9 and 16, although there have been cases of others. These result in excess genetic information that causes errors in instructions for  protein production. Genetic proteins make up everything in the body, thus trisomy and other errors in chromosome number can affect the entire body. 

Previously, many trisomies have been regarded as “incompatible with life,” as many babies born with trisomy would die soon after birth, or early in childhood. Babies born with trisomy often experience heart defects, developmental delays, neurological symptoms, slow growth, and other symptoms specific to their particular disorder, requiring intense lifelong medical care. However, recent developments in medical technology have allowed many trisomy patients to live longer, happier lives. Thanks to recent medical advancements, they are able to experience childhood, school, music, and other moments that may seem guaranteed for others. 

Other chromosomal anomalies include deletion or more rarely duplication of specific chromosome sections such as 22q11.2 deletion (DiGeorge syndrome), or Palliater Killian syndrome, a duplication of part of the 12th chromosome. These disorders often have milder symptoms than those affecting entire chromosomes. Most children and adults with chromosomal abnormalities live longer and more fulfilling lives now than those in past history, with therapies and medical specialists following them for life to treat symptoms and secondary disorders. Inclusion and accessibility in general society allows them the same freedom in the world as anyone else. 

March is Trisomy Awareness Month, which aims to educate people about some of the most common chromosomal anomalies. Although doctors’ favorite words to describe trisomy include “abnormality” “syndrome” and previously “incompatible with life,” many people with these disorders and their families often think of none of these words. Many trisomy patients require lifelong treatments and therapies like occupational therapy, speech therapy, and physical therapy, but with proper care, most still have many of the same experiences as those with the standard number of chromosomes. 

Information gathered from National Institutes of Health, MedicinePlus Genetics, and Cleveland Clinic.