Who Should Be Tested with Array CGH?

Array CGH may be used for:

• People with developmental delay or mental retardation of unknown cause
• People with multiple birth defects
• People with unusual features that don’t look like other family members
• People with autism spectrum disorders
• Pregnancies with birth defects found by prenatal ultrasound
• Pregnancy loss (miscarriage or stillbirth) with birth defects

Array CGH testing should usually be done along with chromosome analysis, or after a chromosome analysis has been done. These tests both look for chromosome changes, but they do it in different ways, so both are often needed.

There are many reasons to look for a cause of these health and learning problems with array CGH testing. While finding a cause doesn’t cure or fix the problems, it can:

• Provide an answer about why the person has these signs and symptoms
• Give you and your doctor information about what to expect in the future
• Improve health screening and prevention for some conditions
• Allow for testing of family members
• Give you accurate information about the chances to have another affected child and possibly provide prenatal diagnosis options
  
• Let you connect with other families and get support services from schools and community
• Explain why a pregnancy loss happened

Definitions

It is important to understand the ways that doctors and other professionals describe and diagnose some of the health and learning problems that can be caused by chromosome changes.

Developmental delay (DD) happens when a young child has a lag or slowness in reaching milestones like sitting, walking, and talking compared to other children the same age. Delays can be in only one area – like talking, thinking, moving, or interacting. They can also be more “global,” affecting more than one set of skills. DD is usually used for children under 5 years old. About 1% to 3% of children have DD. Some children with DD will have mental retardation, while others will “catch up” to their peers and have typical learning later in childhood.

Mental retardation (MR) is defined by the World Health Organization based on tests of intelligence (IQ tests). An IQ score of less than 70 is considered MR. MR can be divided into types: mild (IQ 50-70), moderate (IQ 35-50), severe (20-35), and profound (<20). About 1% to 3% of people have MR. Mild MR is much more common than moderate or severe MR.

A birth defect is an abnormality of the way a body part is formed or how it works. Thousands of different birth defects have been identified, but some common ones include cleft lip and palate, spina bifida, and heart defects. Some people have one birth defect, while others have more than one.

Autism and autism spectrum disorders (ASD) are a group of conditions defined by difficulties with social interaction, communication, and unusual behaviors. There is a wide range of how a person can be affected with an autistic disorder. The spectrum includes people with autism, Asperger syndrome, and pervasive developmental delay (PDD).