Pediatric Genetics

Who should see a pediatric geneticist?

Many different concerns bring children and their families to a pediatric geneticist. Children may:

  • Be at risk for a genetic condition or syndrome because of a family member with a genetic condition
  • Have more than one birth defect
  • Have a developmental delay or an intellectual disability that does not have a known cause
  • Have many unexplained health problems and a parent or physician requesting an evaluation

Why should I see a pediatric geneticist?

When children have health conditions, their parents often have questions like:

  • Why does my child have this health condition?
  • Could my future children or my child’s children have a similar health condition?
  • Where can we get more information?

Sometimes it is difficult to get clear answers to these questions. A genetic specialist can help give information about these rare conditions.

What does a pediatric geneticist do?

An initial outpatient visit usually lasts about 90 minutes. The patient is examined, and with permission, photographs may be taken. At the end of the visit, all findings are reviewed with the patient's family and recommendations are made. During the visit, you can expect the geneticist and genetic counselor/genetic nurse to:

  • Work with the family to outline their family history and a three-generation family history, including both sides of the family. This family history may reveal an underlying genetic issue in the family.
  • Diagnose and provide detailed information about genetic conditions.
  • Recommend and interpret genetic testing. They will also give the family more information about the child’s health condition.
  • Recommend appropriate treatment and coordinate care.
  • Refer to resources.

What is a birth defect?

A birth defect is a health problem or physical change, present in a baby at the time he/she is born.  Some birth defects may be minor but other birth defects may be more serious, like a heart problem. Birth defects are also called congenital anomalies or congenital abnormalities. Congenital means "present at birth". Anomalies and abnormalities mean that there is a problem with a baby.

What causes birth defects?

Both genetic and environmental factors can cause birth defects. Some inherited birth defects are in a predictable pattern and caused by single gene changes or chromosome anomalies. Environmental factors or environmental substances that can cause birth defects are called teratogens. They include alcohol, certain drugs/medications, infections, and certain chemicals. More information on teratogen exposure.

Other birth defects appear to be caused by a combination of one or more genes and environmental exposures. This is called “multi-factorial inheritance.” In some cases, a person may inherit one or more genes that make him/or her more likely to have a birth defect. One example is being around certain environmental substances like cigarette smoke.  These individuals are more likely to have a birth defect. But if the individual is not exposed to the environmental substance before birth, they won't be at risk for the harms of that exposure. See more information about genetic inheritance patterns here.

What if my child has a birth defect?

You may be interested in having your child evaluated by a pediatric geneticist to identify if the birth defect could be part of an underlying genetic syndrome. A genetic evaluation may give you and your family more information about the child’s expected progress. The evaluation may identify the risk for a similar concern in future pregnancies.

What is a family history?

In medicine, a family history is part of a person’s medical history. Health professionals ask questions to find out whether a person is at risk for a particular disease. They base this on their family’s combination of shared genes, environment, behaviors, and culture.

How is a family history helpful?

Knowing your family history can give you a lot of information about your health risks and the risks for your children.

  • It can help you learn about diseases or conditions that you have a risk of getting
  • It can point out behaviors (smoking or inactivity) or environmental exposures (secondhand smoke, farm chemicals) that may increase your risk or your children’s risk for disease
  • It can help you and your doctors know what health problems you should be on the lookout for in yourself and your children so that problems can be found early or prevented

Where can I learn more about how my family history affects my health?

CDC has information about how you can ask your family about your family history.  Use their family history tool to record family history and see what you can learn.

Genetic Syndromes

Chromosomal Disorders

Genetic disorders can happen when there is too much or too little chromosomal material. They can also happen when an abnormal rearrangement (translocation) is present. Chromosomes, which are structural elements containing genes, normally occur in 23 pairs. The first 22 are called autosomes and the last pair is called the sex pair: XX (female) and XY (male).

Chromosomal Disorders Information

Down syndrome

Trisomy 18 (link 1)
Trisomy 18 (link 2)

Trisomy 13 (link 1)
Trisomy 13 (link 2)

Turner syndrome (link 1)
Turner syndrome (link 2)

Deletion 22q11.2 (DiGeorge, VCFS) (link 1)
Deletion 22q11.2 (DiGeorge, VCFS) (link 2)

Cri du chat (5p-)

Williams syndrome (link 1)
Williams syndrome (link 2)

Smith-Magenis (link 1)
Smith-Magenis (link 2)

Other chromosomal anomalies

Single Gene Disorders

Genetic disorders can also result when a change or mutation occurs in a gene. Genes carry bits of information that determines the growth and function of a person. Half of our genes come from our mother and half from our father. In some cases, only having one mutation in a gene will result in a genetic disorder. Other genetic conditions result from two genetic mutations.  One comes from the mother, and the other from the father. Learn more about genetic inheritance patterns here.  

Single Gene Disorders

Cystic fibrosis (link 1)
Cystic fibrosis (link 2)

Rett syndrome (link 1)
Rett syndrome (link 2)

Sickle cell (link 1)
Sickle cell (link 2)
Sickle cell (link 3)

Duchenne muscular dystrophy (DMD)

Fragile X syndrome


Marfan syndrome

Ehlers-Danlos syndrome


PKU (link 1)
PKU (link 2)

Tay-Sachs disease

Genetic Testing

Chromosome Analysis

Each cell in the body contains 46 chromosomes: 22 pairs of identical chromosomes and either two X chromosomes (in a female) or one X and one Y chromosome (in a male). Each chromosome contains many genes which are the blueprints that control our development.

To study chromosomes, cells (usually from a blood sample) are grown in the laboratory. The cells are broken open so that the chromosomes spread out on the microscope slide. The chromosomes are then stained and analyzed under the microscope. 

Fluorescence in Situ Hybridization (FISH) Studies

In FISH, fluorescent molecules attach to specific areas of the chromosome. This allows the laboratory to study smaller areas of the chromosome. It also allows the laboratory to count the number of certain chromosomes without having to wait for the cells to grow.
Your physician may request a FISH study to identify a genetic disorder missing a very small piece of chromosome material. The piece may be so small that anormal chromosome study would not detect it under the microscope.

Array Comparative Genomic Hybridization (CGH) Testing

Microarray-based (array CGH) is a method for detecting extremely small chromosomal imbalances in patients. Array CGH enables the laboratory to look at all a person’s genetic material or DNA at a level that is not possible with routine chromosome testing.  This is also called genome-wide screening.

Single Gene Testing  

Single gene tests look at the DNA, the chemical database that has instructions for your body's functions, of specific genes. Genetic testing can reveal changes in your genes that may cause illness or disease.

Genetic testing can provide important information for diagnosing, treating, and preventing illness, there are limitations. For example, if you are a healthy person, an abnormal result from genetic testing does not always mean you will develop a disease. In some situations, a normal result does not guarantee that you will not have a certain disorder.  Some genetic syndromes do not have testing available. Your geneticist will use a clinical basis to make a diagnosis.


Early Childhood Intervention - A Texas program for families with children birth up to age 3, with disabilities and developmental delay.  ECI supports families to help their children reach their potential through developmental services.  Services are provided by a variety of local agencies and organizations across Texas.

National Organization for Rare Disorders (NORD) - This site is dedicated to helping people with rare diseases and assisting the organizations that serve them. NORD is committed to the identification, treatment, and cure of rare disorders through programs of education, advocacy, research, and service.

Genetic Alliance - The Genetic Alliance is an international organization of families, professionals, and genetic support organizations that work to improve the quality of life for individuals dealing with genetic conditions. Disease-specific information and resources are available. A genetic counseling helpline is available for more information or to discuss questions and concerns. 

March of Dimes - Provides information on birth defects, genetic disorders, and many pregnancy issues.  Fact sheets on specific genetic conditions are available.

Genetics Home Reference - National Institute of Health - Your guide to understanding genetic conditions. You’ll have access to a full review of most genetic conditions categorized by organ system, genes, and chromosomes.  

Consumer-friendly information on the effects of genetic variation is also available.

Chromosome Deletion Outreach - A nonprofit organization for parents with children affected by a wide range of chromosome disorders, including deletions, duplications, trisomies, inversions, translocations, and rings.