Doctors as Detectives

When it comes to genomics, think of your child’s doctor as a detective.

At Cincinnati Children's, doctors use genetic and genomic information to diagnosis and treat diseases. For instance, genomics can help doctors know which medicine will work best in which patient (this is known as precision medicine). Someday, clinicians may be able to use such information to prevent diseases from ever starting.

But finding answers in the genome isn’t always easy. The human genome contains about 19,000 genes (and about three billion letters). Looking at a whole genome at one time can be an enormous undertaking, like reading dictionary after dictionary, cover to cover.

Some people may have symptoms of a disease, but never have a name for what they have. Without a clear diagnosis, they don’t know what might happen in the future. That’s when a doctor becomes a detective and may look to the genome for answers.

It turns out that genes make up only about one percent of the whole genome. The area that has just genes that make proteins – that one percent – is known as the exome. Proteins make tissues and organs. So, an issue with a gene that makes a defective protein can impact the development of healthy tissues and organs. Sometimes doctors will just look for a problem in this area with a test called whole exome sequencing.

Genome Sequencing

When a doctor or researcher wants to sequence a patient’s genome or exome, he or she will read the pattern of letters from the patient’s cells to look for a variant. That is, letters that are in the wrong order from the typical spelling, or letters that are extra, missing, or repeated. Learn more about this in our Guide to Genomics for Families. 

Researchers now think there may be things other than variants in the genome that can signify issues. Research leads us to believe that something happens in the other 99 percent of the genome – the places between genes. It is thought that these variants can lead to a change in gene expression and regulation – or the way the gene works.