Biology Reference
In-Depth Information
gray hair just above the forehead. Her left eye was blue and her right,
brown. There was no dystopia canthorum. Her nose was well formed. Her
skin was evenly pigmented.
6.2.5 Clinical Diagnosis and Recommendations
A diagnosis of Waardenburg syndrome type II was made. (see Table 9.3.)
Because of the potential implications for family planning, genetic evalua-
tion of other family members (especially S.K.'s aunt and uncle) would be
recommended to confirm or rule out Waardenburg syndrome.
6.2.6 Genetic Counseling Issues
During this genetic counseling session, the features of Waardenburg syn-
drome (WS) would be discussed. A clear explanation would be given to
S.K. to help her understand that WS has caused both her deafness and dif-
ferent colored eyes and has also caused other pigmentary changes in her
family members (white forelock, skin hypopigmentation and early graying
of the hair). A detailed explanation of autosomal-dominant inheritance
with variable expression would take place. S.K., as well as anyone else in
her family with Waardenburg syndrome, would have a 50% chance of
having a child with WS. There is a 50% chance that a person with WS type
II will be deaf. Therefore, S.K. has a 25% chance with each pregnancy to
have a deaf child. S.K. would be advised to return for genetic counseling
when she marries or is planning to have children. She has indicated that
she prefers to marry another deaf person and would be interested in finding
out about their chances of having a deaf child.
6.2.7 Overview of Case 2
This case demonstrates the importance of making an accurate diagnosis of
a syndrome. The associated features of Waardenburg syndrome are rarely
of medical significance and may be subtle; someone not trained in genetics
TABLE 9.3. Waardenburg syndrome
Waardenburg syndrome (WS) is characterized by sensorineural hearing loss that may be
mild to profound and unilateral or bilateral, heterochromia (often one blue and one brown
eye) or bright blue eyes, congenital white forelock or premature greying, and
hypopigmented skin. In rare instances, individuals with Waardenburg syndrome have serious
medical complications, such as Hirschsprung's disease or spina bifida. There are two
common forms of Waardenburg syndrome, types I and II, which are distinguished by the
presence or absence of dystopia canthorum and by the frequency of hearing loss.
Waardenburg syndrome type I is characterized by dystopia canthorum. About 20% of
people with WS type I have a hearing loss. People with Waardenburg syndrome type II
have normally spaced eyes, and about 50% have a hearing loss. All forms of Waardenburg
syndrome are inherited as a dominant trait.
