FISHing for Information on Williams Syndrome
Hirsch, David, The Exceptional Parent
Q My seven-year old daughter was diagnosed with Williams syndrome at age one, based on her appearance and her heart disease (supravalvular aortic stenosis). She does fairly well in her special education classes except for some behavioral problems related to lack of impulse control and poor concentration. Recently, I heard about a diagnostic blood test for Williams syndrome. Would it be beneficial at this point? Would it tell me more than I already know?
A Williams syndrome, also known as Williams-Beuren syndrome, is a rare genetic disorder that occurs in approximately one in 20,000 births. Physical features include a small head, depressed nasal bridge, wide mouth with small chin, full lips and puffiness around the eyes (the so-called "elfin facies"). Heart disorders are found in about 75 percent of children with Williams syndrome, the most common are supravalvular aortic stenosis (the area just above the aortic valve--the aorta is the main artery from the heart--is narrowed) and pulmonary artery stenosis (narrowing of the main artery going from the heart to the lung). Other abnormalities may occur in the urinary tract system, musculoskeletal system and the eyes.
Recently, using a technique known as fluorescent in-situ hybridization (FISH), researchers have found that at least 90 percent of individuals with Williams syndrome have a deletion of part of chromosome number 7. This gene is responsible for the production of elastin, a protein necessary for forming connective tissue and creating ability to stretch. Connective tissue supports and binds other body tissue and parts. Examples are cartilage, ligaments and bone. The FISH technique is also used to diagnose other conditions such as Prader-Willi syndrome, the DiGeorge sequence and Angelman syndrome.
The effects of Williams syndrome goes well beyond low muscle tone and coordination. It affects nearly every body system. Low birth weight and failure to thrive is not unusual. It is also not unusual to have problems with constipation, frequent vomiting, feeding difficulties, colic, fretfulness and abnormal sleep patterns. Blood calcium levels may be elevated in the first two years of life. In some cases infants and young children have very sensitive hearing (hyperacusis) and are distressed by high-pitched but common household sounds such as the dog barking, cabinets closing, or the vacuum cleaner. …