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Genetics Embryology and phenotype of Williams Syndrome

A summary of the embroyologically important genes that lead to Williams syndrome, a rare genetic disorder resulting in an elf-like appearance, and a "peaks and valley's" phenotype of perfect pitch, excellent verbal abilities, poor spatial ability and low IQ. William's syndrome is thought to be the origin of myths of fairies and elves.

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Williams Syndrome: Deletion of embryologically important genes on chromosome 7.

Haploinsufficiency of 7q11.23 caused by problems during cross over.
Occurs in 1/25,000 births (in comparison, Down's syndrome occurs in 1/600)
Phenotypic consequence of each gene deletion is not yet known

Focus on ELN, FZD9, LIMK1

ELN- codes for the protein elastin
Elastin is important in skin, heart, artery, connective tissue, joint make up.
Most prevalent problem caused by haploinsufficiency of ELN is the congenital heart defect Supravalvular Aortic Stenosis
(congenital narrowing of the ascending aorta)

Other problems resulting from the loss of ELN:
-joint limitations
-premature aging of the skin

FZD9- codes for a membrane receptor
Wnt Family binds to FZD9, controls early embryonic events
Mouse homologue to FZD9 is Fzd9
When staining for Fzd9 RNA, found in entire neural tube,
Expression strongest in the telencephalon (youngest part of brain)
Boundaries between parts of the brain were formed by variation in Fzd9 concentrations.
Suggests importance in brain differentiation (also found that there are not left-hemisphere asymmetries associated with grammar formation in those with Williams Syndrome, suggesting an ...

Solution Summary

Williams syndrome is a rare genetic disorder caused by a deletion of genes on chromosome 7, most importantly ELN, FZD9 and LIMK1 . These genes are important during embryogenesis, and result in an interesting phenotype that result in characteristic facial features, renal abnormalities and cognitive peaks and valleys including a low IQ but gifted musical abilities.

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