Chromosomes carry genes that tell the body on how to grow, develop and work. The usual number of chromosomes in each body cell is 46, or 23 pairs. A child inherits half from their birth mother and half from their birth father.

Chromosome diseases are genetic conditions caused by changes in a person’s chromosomes. They happen when the number or structure of chromosomes changes or when some cells have a different chromosome makeup. These changes can impact how the body grows, develops and works. They can lead to many different health conditions.

Below is a summary of how chromosome changes occur.

Changes in chromosome number:

• Trisomy: This is when there is an extra chromosome. A person has three copies of one chromosome instead of the usual two. That is a total of 47 chromosomes in each cell.
• Monosomy: This is when a chromosome is missing. A person has only one copy of a chromosome instead of two. This is a total of 45 chromosomes in each cell.

Changes in chromosome structure:

• Deletion: When a section of a chromosome is missing or lost.
• Duplication: When a section of a chromosome is copied. This results in extra genetic material.
• Inversion: When a chromosome breaks in two places and the piece between turns upside down and reattaches.
• Ring: When the ends of a chromosome have broken off, then attach to form a circle or ring.
• Translocation: When chromosome material moves to a different location. This happens either by swapping parts with another chromosome or when a whole chromosome attaches to another.
• Mosaicism: This happens when a person has two or more types of cells with different chromosome numbers. For example, some cells may have the usual 46 chromosomes, while others have 47.

We are a leading center for diagnosing, treating and researching genetic conditions in both kids and adults.

Among the best: Children’s Wisconsin has one of the best programs in the United States that uses advanced genetic testing. This helps us uncover the causes of diseases and health problems that are hard to diagnose.

Wisconsin’s only: Our Genetics and Genomics Program offers services you can't find anywhere else in the state. Our program helps detect and treat many different types of genetic conditions.

Academic medicine: Our Genetics and Genomics Program experts work with the Medical College of Wisconsin (MCW). MCW is a top medical school and research center. This partnership lets us advance knowledge, drive research and create new treatments.

National leader: We’re the biggest genetics program in Wisconsin. We’re also national leaders in whole-genome sequencing. Our doctors use this to find genetic changes that cause diseases, including rare conditions that are hard to diagnose.

For questions or to schedule a visit, please call (877) 607-5280.

If your family is not able to travel, we may meet with you by phone, email or video. We’ll look over your child’s health records and work with their doctor to plan next steps or get a sample for testing.

Before

Before your visit, we will ask you to:

• Bring records from other doctors, including test results, scans and diagnoses
• Fill out forms about your child's health, symptoms and family history
• Be ready to discuss your child's symptoms, including when they started

During

When we meet with you and your child:

• A doctor and genetics expert may talk with you to learn about your child’s health.
• Your visit may include several visits, exams and tests.
• A genetic counselor may guide you through testing and care plans.

If your family is not able to travel, we may meet with you by phone, email or video. We’ll look over your child’s health records and work with their doctor to plan next steps or get a sample for testing.

After

We’ll share the test results and any updates with you. We’ll guide you through the next steps, discuss treatment options and provide helpful resources.