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Inherited Disorders and Birth Defects

Need for Genetic Testing

03/23/2011

Question:

I have a 5 month old son who was diagnosed with Williams Syndrome within the 1st week of his life (confirmed with microarray). I have 2 older sons, ages 7 and 3 1/2. The 7 year old has no developmental or medical issues and the 3 year old has no issues other than a speech articulation problem. He has been in speech therapy for over a year and his speech therapist suggested that his issue could be related to a genetic problem- specifically on chromosome 7. Does this mean that my husband or I have a genetic issue with chromosome 7? Would genetic testing give us any answers/information? Should our older children be tested to find out if they are carriers of an abnormality?

Answer:

As you probably know, people with Williams syndrome (WS) are missing a part of one of chromosome #7 – this is called a deletion (missing) on chromosome 7 ( specifically at 7q11.2).

People with Williams syndrome often have heart problems, characteristic facial appearance, a unique personality - usually overly friendly, delays in development, and some degree of mental retardation and learning disabilities. Infants often have problems with feeding and may have low muscle tone. Speech is often delayed, but later becomes a strength. While children with Williams syndrome could have articulation problems, these are also very common in children who do not have Williams syndrome. Your 3 year old son’s speech problem may have nothing to do with his brother’s diagnosis of WS.

Williams syndrome is an autosomal dominant disorder, but the vast majority of children with WS are due to chance (de novo occurrences) and are not inherited from a parent. Some recent studies have shown that sometimes a parent, who does not have Williams syndrome, can have a piece of his or her chromosome # 7 inverted, flipped around. While all the genetic material is there and functioning, it is been rearranged. When that person makes eggs or sperm there is a chance that the inverted chromosome # 7 could lose a piece, which involves the genes that cause Williams syndrome, although this has only been report in a few families.

While your 3 year old son’s speech problem is probably not related to a chromosome abnormality, the only way to know this is to have him evaluated. I would recommend that you talk to a geneticist or genetic counselor to discuss your questions in detail. A genetics specialist would also be able to advise you about whether or not it is necessary to have your chromosomes looked at as well.

You can locate one near you at the National Society of Genetic Counselors’ Resource website listed below. Additionally you will find a great deal of information at the Williams Syndrome Association website, also listed below.

Related Resources:

National Society of Genetic Counselors Resource Center
Williams Syndrome Association

For more information:

Go to the Inherited Disorders and Birth Defects health topic, where you can:

Response by:

Anne   Matthews, RN, PhD Anne Matthews, RN, PhD
Associate Professor of Genetics
School of Medicine
Case Western Reserve University