a genetic condition caused by a mutation in the gene (CSPG2 on chromosome 5) encoding chondroitin sulfate proteoglycan-2, also known as versican. Versican is a substance present in the vitreous body of the eye. Symptoms and signs include changes in the vitreous body of the eye, retinal detachment, cataracts, and poor visual adaptation to dark. An association with cleft palate has been described. Studies suggest an irregular autosomal dominant pattern of inheritance.
- Waardenburg, Petrus Johannes
(1886-1979) Dutch ophthalmologist and medical geneticist who described the condition now known as Waardenburg syndrome. The syndrome is characterized by wide bridge of the nose owing to lateral displacement of the inner canthus of each eye, pigmentary disturbance (frontal white blaze of hair, eyes of different color, white eye lashes, leukoderma), and cochlear deafness. Waardenburg […]
- Waardenburg syndrome
A genetic disorder that causes deafness, white forelock (a frontal white blaze of hair), a difference of color between the iris of one eye and the other (heterochromia iridis), white eye lashes, and wide-set inner corners of the eyes. The deafness is typically congenital (present at birth), bilateral, profound sensorineural (nerve) deafness. The severity of […]
- X inactivation
it is a heritable change in gene function without a change in the sequence of the DNA. X inactivation is not restricted to females. It also occurs in males with Klinefelter syndrome who have more than one X chromosome. The phenomenon of X inactivation is also called lyonization after the English geneticist Mary Lyon (1925-) […]
- X, factor
A coagulation factor, a substance in blood essential to the normal clotting process. Production of factor X takes place in the liver and requires vitamin K. The gene for factor X is located on chromosome 13 and is in band 13q34. The “X” in factor X is the Roman numeral “ten.” (All numbered coagulation factors […]
A gene on the X chromosome that is located on the X chromosome. An X-linked disorder is associated with or caused by a gene on the X chromosome.