What causes genetic disorders?

Each cell in the human body contains 23 pairs of chromosomes. You inherit one set of the pair from your father and one set from your mother.  Each chromosome is made up of many genes, about 2,000 in each chromosome, for a total of 50,000 genes in each cell.  These genes make all the proteins in the body, which promote development and growth, and carry out all body functions.

When one or more of these genes or chromosomes are missing or mutated, or if extra chromosomes are present, the proteins may not get made, may be made incorrectly, or too many may be made.  Any of these situations can cause abnormal development and growth and can result in a genetic syndrome.  Sometimes these abnormal genes or chromosomes are passed down from a parent, and sometimes they occur spontaneously without reason.  

For help in understanding the terms used in genetics, see the talking glossary of genetic terms from the National Human Genome Research Institute.  Here, you can listen to detailed explanations of these complicated terms.

What are genetic syndromes?

A syndrome is a disease or disorder that has more than one identifying feature or symptom.  Each particular genetic syndrome will have many typical features, depending on which aspects of development are affected by the abnormal genes or chromosomes.

A child might be born with obvious body deformities, abnormal organ function (for example:  heart, brain, gut, or kidney), or neurological problems (for example, when a baby’s body is floppy or the baby is unable to nurse or bottle feed).  However, many of the genetic syndromes start to take effect only once the baby has been born and is starting to feed and grow.  These babies may look and act entirely normal at birth, but then develop problems later on in life.

This is a big and complex topic, and we are learning more and more about genetic syndromes every day. 

How can I find out more to help me understand this stuff?

Here are some links to sites that explain more about genes and genetic syndromes:

• What Are Genetic Disorders?, from the University of Utah’s Genetic Science Learning Center, does a good job of explaining it all.
• DNA from the Beginning—an animated introduction to the basics of DNA, genes and heredity.
• Your Genes, Your Health—a multimedia guide to genetic disorders.
• Birth Defects can have genetic causes.
• When Your Baby has a Birth Defect.
• Genetic Disorders from Medline Plus has links to lots of helpful information.

What are genetic counseling and genetic testing?

Here are some links to more information on genetic counseling and genetic testing:

• Genetics at the Department of Pediatrics, University of Michigan Health System.
• Genetic Counseling and Your Family History—information from the March of Dimes, including how to find a genetic counselor.
• Genetic Counseling from KidsHealth describes who should seek counseling, what to expect, and how to decide what to do after counseling.
• FAQs about genetic counselors and National Society of Genetic Counselors (NSGC)—includes information on how to locate a counselor near you.
• An Introduction to Genetics and Genetic Testing is basic and easy to understand.
• Understanding Gene Testing has helpful illustrations, and gets into the nitty gritty.
• Genetic testing must be in best interests of children—a press release from the American Academy of Pediatrics (AAP)
• Policy statement from the AAP on the Ethical Issues with Genetic Testing in Pediatrics.

How can I find out more about specific genetic syndromes?

• YourChild:  Angelman Syndrome
• Cri du Chat Syndrome (5 P-)
• YourChild:  Down Syndrome (Trisomy 21)
• YourChild:  Fragile X Syndrome
• Klinefelter Syndrome
• YourChild: Neurofibromatosis
• YourChild:  Prader-Willi Syndrome
• YourChild: Rett Syndrome
• Smith Magenis Syndrome
• YourChild:  Turner Syndrome
• Velocardiofacial Syndrome
• YourChild:  Williams Syndrome
• YourChild:  XXX Syndrome (Triple X)
• The National Organization for Rare Disorders (NORD) is a federation of voluntary health organizations serving people with rare diseases and their families.  They maintain a database of over 1,100 rare diseases—many of which are genetic syndromes.

Are there any good books about genetic syndromes?

Genetics and Mental Retardation Syndromes: A New Look at Behavior and Interventions
by Elisabeth M. Dykens, Robert M. Hodapp, and Brenda M. Finucane. 

What are some other good general resources related to genetic syndromes?

• YourChild:  Chronic Conditions
• YourChild:  Developmental Delay
• YourChild:  Siblings of Children with Special Needs
• The National Institutes of Health (NIH) Office of Rare Diseases website is a place where you can find information on thousands of rare diseases, including current research, publications from scientific and medical journals, completed research, ongoing studies, and patient support groups.
• The National Organization of Rare Diseases is a federation of voluntary health organizations dedicated to helping people with rare "orphan" diseases and assisting the organizations that serve them.
• General Principles in the Care of Children and Adolescents with Genetic Disorders and Other Chronic Health Conditions—a policy statement from American Academy of Pediatrics.
• The Genetic Alliance is an international coalition that supports people with genetic conditions and their families, educates the public and advocates for consumer-informed public policies.  They have an on-line genetic resource directory.
• Resources for Children with Disabilities:  Genetic Syndromes

Still have questions about this topic?  Go to our survey to ask your questions, and we’ll try to answer them on an upcoming YourChild podcast.

 

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Compiled by Kyla Boyse, R.N. Reviewed by faculty and staff at the University of Michigan

Updated May 2007

U-M Health System Related Sites:
U-M Pediatrics

Our editorial policy
The information and links we provide are reviewed by University of Michigan developmental and behavioral pediatricians and child psychologists who are experts in child behavioral health. In choosing the links we provide, we use strict criteria to ensure that the information is accurate, and the source is reputable. As much as possible, we focus on information that is based on research. In areas where there is inadequate research, we include information compatible with prevailing expert opinion.

This website is updated regularly, but because of the dynamic nature of the Internet, we cannot be responsible for misinformation that may be accessed through the links provided. As always, this website is not a tool for self-diagnosis, and is not a substitute for professional care.

 

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