Figure 1. Two photographs showing typical facial characteristics of children with Williams syndrome.

Figure 2. The making of a cognitive profile. As part of an effort to pinpoint cognitive features that are characteristic of Williams people, investigators have compared subjects with Williams and with Down syndrome on tests of specific abilities.

(a) One test, which asked adolescents to copy from memory a letter D that was built from a collection of small Ys, revealed impairment in integrating details into a larger configuration. The Williams group tended to draw only Ys, whereas the Down group tended to maintain the overall configuration but omit local details.

(b) Another test, in which subjects had to invent a story for a series of wordless pictures, revealed that Williams people can often generate well-structured narratives. Their responses are given below:

Williams subject, age 17, IQ 50: ‘Once upon a time when it was dark at night, the boy had a frog. The boy was looking at the frog, sitting on the chair, on the table, and the dog was looking through, looking up to the frog in a jar. That night he sleeped and slept for a long time, the dog did. But the frog was not gonna go to sleep. The frog went out from the jar. And when the frog went out, the boy and the dog were still sleeping. Next morning it was beautiful in the morning. It was bright, and the sun was nice and warm. Then suddenly when he opened his eyes, he looked at the jar and then suddenly the frog was not there. The jar was empty. There was no frog to be found.’

Down subject, age 18 IQ 55: ‘The frog is in the jar. The jar is on the floor. The jar is on the floor. That's it. The stool is broke. The clothes is laying there.’

Reproduced with permission from Ursula Bellugi, The Salk Institute, La Jolla, California.

Figure 3. Basic anatomy of the brain.

Figure 4. Microdeletion and FISH test. Tiny deletion from one of the two copies of chromosome 7 in cells is the cause of Williams syndrome (drawing). The excised region can contain 15 or more genes, only some of which have been identified. A diagnostic test is based on the discovery that the gene for elastin is usually among those lost. The test flags copies of chromosome 7 with a fluorescent green tag and flags the gene for elastin with a fluorescent red tag. Chromosome (blue) from a cell in a normal subject (top micrograph) will show two green and two red signals, indicating that both copies of chromosome 7 are present and that each carries the gene for elastin. But the Williams people lack one copy of the gene, and so one copy of chromosome 7 will lack a red signal (bottom micrograph).