William syndrome is a rare genetic disorder that affects many parts of the body. It is basically a neuro-developmental disorder.
Genetics
It is caused by microdeletion of long arm of chromosome 7 (7q 11.23).This area has about 26-28 genes the most important one among them is elastin gene(eln).
This microdeletion is present either in the sperm or ovum or rarely it may inherit as a autosomal dominant disorder.
PRESENTATIONS
Elastin gene is responsible for most of the presentations.
Children with William syndrome exhibit a characteristic Elfin like facies .
They have a broad forehead,puffiness around eyes,depressed nasal bridge,broad nose and microcephaly.
Cardiovascular abnormalities like supravalvular aortic stenosis and pulmonary stenosis are common in these kids which leads to Hypertension and Heartmurmurs.
They have increased Vitamin D absorption which leads to hypercalcemia and it’s related symptoms (Colic,irritability,constipation,Urinary stones).
Blue and green eyed children with Williams syndrome can have a prominent STARBURST or white lacy pattern on their Iris.( shown in the picture below)
Neurological symptoms(COCKTAIL PARTY PERSONALITY)
Due to multiple genes that are missing ,there are many effects on the brain including abnormalities in the cerebellum ,right parietal lobe and left frontal regions.
Due to abnormal development of frontocerebellar pathways there is deficit in coordination and execution of fine motor skills such as drawing and writing.
Right parietal area handles visuospatial skills ,due to defective development visuospatial skills and orientation to space are very poor in these children.
Due to defective fronto dorsal area,there is decreased inhibition activity, this is the reason why people with Williams are hyperverbal.
Neuroimaging studies demonstrate that individuals with Williams have diminished Amygdala reactivity to socially frightening stimuli but demonstrate hyperreactivity in the amygdala to nonsocial frightening stimuli ( frightening animals).
Increased activation of left auditory cortex has been observed in people with Williams syndrome,this tells about their fondness of music and rhythm propensity.
They have higher anxiety levels and phobias.
People with Williams also reported to have Hyperacusis(increased sensitivity to sound).
They have low IQ levels but they can be highly verbal relative to their IQ.
Infants with Williams make frequent eye contact ,young children will often approach and hug strangers.They have high Empathy.
Diagnosis
Generally based on the characteristic features along with evidence from FISH ( Fluorescent insitu hybridization).
Follow up
Annual cardiology evaluations
Restriction of Vitamin D diet
Anti hypertensive agents
Developmental and speech therapy was found to be useful.
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