Williams syndrome

Williams syndrome (WS; also Williams-Beuren syndrome or WBS) is a rare neurodevelopmental disorder caused by a deletion of about 26 genes from the long arm of chromosome 7. It is characterized by a distinctive, "elfin" facial appearance, along with a low nasal bridge; an unusually cheerful demeanor and ease with strangers, coupled with unpredictably occurring negative outbursts; a predisposition to violent outbursts; mental retardation coupled with unusual (for persons who are diagnosed as mentally retarded) language skills; a love for music; and cardiovascular problems, such as supravalvular aortic stenosis and transient hypercalcaemia. The syndrome was first identified in 1961 by Dr. J. C. P. Williams of New Zealand.

Symptoms
Individuals with Williams syndrome are highly verbal and sociable, but lack common sense and typically have inhibited intelligence. Individuals with WS hyper-focus on the eyes of others in social engagements. There also appears to be a higher prevalence of left-handedness and left-eye dominance in those with Williams, and cases of absolute pitch appear to be significantly higher amongst those with the condition. People with Williams syndrome often have hyperacusis and phonophobia which resembles noise-induced hearing loss, but this may be due to a malfunctioning auditory nerve. Individuals with Williams syndrome also report higher levels of fears, which may be associated with hyperacusis.

Visual perception
Individuals with Williams syndrome have problems with visual processing, but this is related to difficulty in dealing with complex spatial relationships rather than to issues with depth perception.

Cause
Williams syndrome is caused by the deletion of genetic material from the region q11.23 of chromosome 7. The deleted region includes more than 20 genes, and researchers believe that the loss of several of these genes probably contributes to the characteristic features of this disorder. , ELN,, , and are among the genes that are typically deleted in people with Williams syndrome. Researchers have found that loss of the ELN gene, which codes for the protein elastin, is associated with the connective-tissue abnormalities and cardiovascular disease (specifically supravalvular aortic stenosis (SVAS) and supravalvular pulmonary stenosis (SVPS)) found in many people with this syndrome. Studies suggest that deletion of LIMK1, GTF2I, GTF2IRD1, and perhaps other genes may help explain the characteristic difficulties with visual–spatial tasks. Additionally, there is evidence that the loss of several of these genes, including CLIP2, may contribute to the unique behavioral characteristics, learning disabilities, and other cognitive difficulties seen in Williams syndrome.

Management
Guidelines published by the American Academy of Pediatrics include cardiology evaluations, anesthesia consultation for any child requiring surgery, developmental and psychoeducational assessment, and many other examination, laboratory, and anticipatory guidance recommendations.

Epidemiology
Williams syndrome has an estimated prevalence of 1 in 7,500 to 1 in 20,000.