CHROMOSOMAL ABNORMALITIES

Definition: A type of genetic condition caused by large changes in genetic material. Most often found in children with multiple birth defects or complex problems starting from birth.

1. What are chromosomes?

Chromosomes are the structures in all the cells of our body that store our genetic information. They are large pieces of deoxyribonucleic acid (DNA). Human beings normally have forty-six chromosomes.

2. What features does my baby have that make you suspect this kind of disorder?

Your baby has physical features that are unusual for your family. These may be major differences, like missing eyes or an abnormal heart. Or the different features may be minor, like ears that are not in the right place or short fingers. The specific features vary depending on which chromosome is involved.

3. How did my baby develop this type of condition?

Most of the time, chromosome problems happen during formation of the egg or sperm. Sometimes a chromosomal rearrangement happens soon after conception in the early embryo. Rarely, the chromosome problem is inherited from a parent. When it is inherited, the parent may have a similar problem, or the parent may be unaffected.

4. What tests are needed to further define the disorder?

The most common test is a chromosome analysis, or karyotype. This is done using a blood sample. About a teaspoon of blood is collected and sent to a cytogenetics lab (the kind of lab that looks at chromo- somes). The lab will process the sample, take pictures of the chromo- somes, count them, and look at them closely. The lab is looking for large changes in the chromosomes, such as a missing or extra piece. This type of test does not see small changes in the genetic material. The chromosome analysis takes ten days to two weeks.

Fluorescence in situ hybridization (FISH) is a way of looking at smaller pieces of genetic material. Depending upon your baby’s specific features, a FISH test may be ordered. A newer type of test is the Chromosome Microarray Analysis (CMA), which can also test for changes in smaller pieces of genetic material. It may be ordered rather than a FISH test.

5. What kind of impairments can occur as a result of this condition?

If your baby has a physical abnormality, like a missing hand or foot, there will be impairments because of that. Most chromosome abnormalities cause some amount of mental retardation. The retardation can be severe. Large chromosome abnormalities, which involve significant changes in the genetic material, can cause death in infancy or childhood.

6. Is this disorder treatable?

There is no cure for chromosome problems. There is no way to take out the abnormal chromosome and put in a normal one. However, your child will get whatever treatment is needed. Treatment may include physical therapy or heart surgery and will be determined by the specific needs of your child. 

7. Is it possible that any of our future children might be born with this disorder?

When a baby has a chromosome problem, it is typical to test both parents. If the parents both have normal chromosomes, the risk of giving birth to another affected child is not increased; the risk is the same as it is for anyone. (There is never zero risk.) If one parent has a chromosome abnormality, the chance of having another child affected with a chromosome problem is at least fifty-fifty. Depending upon what the chromosome problem is, the chance of having an affected child may be as high as two out of three.

8. Do we need to consult with a geneticist or any other specialist?

Yes. Your baby should be seen by a doctor who specializes in genetics. The geneticist can help get testing done and talk to you about what to expect from your child. The geneticist can also discuss your chances of having other affected children and may be able to put you in touch with other families who have children with the same problem.

9. What kind of special plans should be made to care for the baby once we arrive home?

Your baby will need all the routine pediatric care, including immunizations. If your baby has special health needs, like tube feedings, you should be taught about that at the hospital. Sometimes babies with chromosome problems are not expected to live very long. You may choose to enroll your baby in a hospice program. Hospice programs support you and the baby so that the family can have a good quality of life, even if your baby’s time within the family is short.

10. When do you wish to see my baby again for this condition?

It is likely that your baby will have many different doctors. There will also be occupational and physical therapy, and your baby may need surgery. Your pediatrician can help coordinate all the different doctors. 

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