(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 made many other contributions to genetics, In 1932 he suggested that Down syndrome might be due to a chromosome abnormality, which was confirmed in 1959 by Jerome Lejeune and colleagues in Paris.
Dr. Waardenburg did his medical studies at the University of Utrecht, trained in ophthalmology, and wrote his doctoral thesis on the hereditary basis of features of the eye. His interest in genetics was reinforced when his wife gave birth to monozygous twin daughters. He extended his research to twin studies.
In 1947 at a meeting of the Dutch Ophthalmological Society in Utrecht, Waardenburg presented a deaf-mute tailor with what is now called Waardenburg syndrome. The first description of this syndrome, however, may have been recorded in 1888 by the German writer Karl May.
- 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.
High-energy radiation with waves shorter than those of visible light. X-ray is used in low doses to make images that help to diagnose diseases and in high doses to treat cancer.