The Answer Is In Your Chromosomes


Finding a change within a chromosome that is causing a health condition is complicated. Advances in our understanding have enabled medical laboratories to now find answers for patients faster and more accurately.

Patricia Crotwell-Leiferman, PhD, director of the Sanford Medical Genetics Laboratory, says, “The division of the laboratory that I run is Cytogenetics. We perform clinical diagnostic testing, which is a little more complicated, and always slower, than getting a blood sugar level or red blood cell count. We study chromosomes, their inheritance, and their relationship to human diseases and disorders—some inherited and some acquired.”

The Basics

Every living thing on Earth is made up of cells, the smallest units of life, and the complexity of the information in a single cell is extraordinary. Everything that makes you who you are is wrapped into an object so small that it must be looked at using a microscope. Yet, the genetic information within determines all growth, development, reproduction and even health.

Your body is made up of trillions of these cells, and most contain your entire genome, or the entirety of your genetic code in the form of DNA. The DNA contains regions called genes that are the instructions for making proteins, and these proteins determine the function of the cell, individual traits or characteristics, and so much more.

“Chromosomes are essentially packages of DNA plus proteins. The proteins create a scaffold that DNA winds around, allowing the very long strands of DNA to shorten and squish down into a tiny little body that can fit inside a cell. Humans have, on average, 46 chromosomes grouped into 23 pairs, half inherited from your biological mother and half from your biological father,” explains Dr. Crotwell-Leiferman.

While the majority of human DNA is the same between any two unrelated people, there are slight changes, or variants, that make each person different. These can be inherited or in some cases, acquired during one’s lifetime due to lifestyle, the environment and other factors. Some variants are harmless, some beneficial and others can affect a person’s health.

Chromosome Changes

Cytogenetic technologists can look carefully at a person’s chromosome structure to determine if a chromosome change is present to describe the type of change and to explain what this means for the patient. 

“A cell’s replication process, or when a cell makes a copy of itself, is very accurate in the vast majority of people, but it’s not perfect. That the process is not perfect is the source of changes in individual genes and rearrangements of chromosomes,” explains Dr. Crotwell-Leiferman. “If you are 99.99 percent accurate, you are still .01 percent inaccurate. Given enough time and cell divisions, errors will happen.” 

Dr. Crotwell-Leiferman continues, “For the most part, cells have the ability to self-recognize errors and undergo a process called programmed cell death, or apoptosis. However, when cases of acquired abnormalities occur, like cancers, a cell escapes recognition of being abnormal or escapes programmed cell death. These can become immortal cells, and an immortal cell continues to divide and divide, until becoming a solid tumor, such as a brain tumor, or a liquid tumor in the bone marrow or lymph systems, as is seen in leukemias and lymphomas. 

The Lab Process

“What we do with chromosomes really depends on the question we are trying to answer for the patient and ordering provider,” explains Dr. Crotwell-Leiferman. “If we need to look at the chromosomes physically, what we need to do is get the cells to grow first, which can take several days or weeks, depending on the type of sample.”

Once the cells are prepared for the microscope, cytogenetic technologists count the number of chromosomes, determine the identity and number of the sex chromosomes, and analyze each chromosome pair band for band for their entire length. This attention to detail is necessary to detect missing material (a deletion), extra material (a duplication), an inversion or perhaps an insertion of genetic material from another chromosome.

“Those days where we detect a chromosome change are bittersweet because while we have found an answer for the patient, which is our goal, the families of patients may sometimes be very saddened by the result,” says Dr. Crowell-Leiferman. “At other times, they are grateful to have a result that is diagnostic. Even with the bittersweet aspect of our work, we all are enthusiastic about the genetic work that we do and our ability to help patients. 

To learn more, visit or call (605) 312-GENE.

  • Sponsored

DISCLAIMER: The views of the author are not necessarily those of this station, its owners, officers, agents or employees.

Copyright 2021 Nexstar Media Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

Continuing The Conversation
See Full Weather Forecast

Trending Stories

Don't Miss!

More Don't Miss