Understanding the Basics of Genetic Disorders

You’ve heard terms like genes, DNA, the Human Genome Project, and chromosomes. But what do these words mean exactly? Increase your genetic vocabulary so you’ll understand more about genetic disorders.

What Is DNA?

DNA (deoxyribonucleic acid) carries the genetic information in the body’s cells. DNA is made up of four similar chemicals (called bases and abbreviated A, T, C, and G) that are repeated over and over in pairs.

What Is a Gene?

A gene is a distinct portion of a cell’s DNA. Genes are coded instructions for making everything the body needs, especially proteins. Human beings have about 25,000 genes. Researchers have discovered what some of our genes do, and have found some that are associated with disorders (such as cystic fibrosis or Huntington’s disease).

 

There are, though, many genes whose functions are still unknown.

What Are Proteins?

Proteins are chains of chemical building blocks called amino acids. A protein could contain just a few amino acids in its chain or it could have several thousands. Proteins form the basis for most of what the body does, such as digestion, making energy and growing.

What Are Chromosomes?

Genes are packaged in bundles called chromosomes. Humans have 23 pairs of chromosomes (for a total of 46). Of those, 1 pair is the sex chromosomes (determines whether you are male or female, plus some other body characteristics), and the other 22 pairs are autosomal chromosomes (determine the rest of the body’s makeup).

What Is a Mutation?

The particular order of the pairs of As, Ts, Cs, and Gs is extremely important in the DNA. Sometimes there is a mistake — one of the pairs gets switched, dropped, or repeated. This changes the coding for one or more genes. This is called genetic mutation. A mutation maybe disease-causing or harmless.

 

Another way the DNA code could be changed is by errors in the chromosomes. Parts of a chromosome could break off, switch with part of another chromosome, or be swapped within the same chromosome. If any of these or other mistakes occurs then changes (mutations) happen in the gene coding. Sometimes there may be 3 or more copies of a chromosome, or only one chromosome, instead of the normal pair.