Biology Reference
In-Depth Information
During the genetic counseling session, a detailed description of autoso-
mal-recessive inheritance would be provided. All of D.S.'s future children
will be carriers of the gene causing his deafness. Because D.S. and M.S. have
different types of hearing loss, their chances of having congenitally deaf
children appear to be low. However, D.S. has an apparently common form
of hearing loss as is evident by the fact that his mother and father and one
sister married someone with the same type of hearing loss. Therefore, it is
possible that M.S. may be a carrier of the same type of deafness as D.S.,
in which case they would have a 50/50 chance of having deaf or hearing
children with each pregnancy.
This couple's perception of deafness and their desires for deaf or hearing
children would be explored. They may have never considered the possibil-
ity of having a hard of hearing child and may be surprised to learn about
this chance. In addition, they may have suspected that their chance to have
deaf children was high because D.S. has a deaf family.
They would be referred to a genetics center performing molecular
genetic studies of nonsyndromic deafness. Depending on whether the test-
ing at that center is performed on a clinical or research basis and whether
D.S. has a form of deafness for which there is currently a test, this testing
may or may not aid this couple in decisions about family planning.
6.1.7 Overview of Case 1
This case demonstrates the complexity of counseling deaf couples and the
potential ability of molecular testing to aid genetic counselors in providing
the most accurate recurrence risk information possible. There are at least
three different types of hearing loss in this family. Identifying the gene that
caused D.S.'s deafness and testing M.S. to see whether she carries that gene
will allow a genetic counselor to determine whether the couple's chance to
have a deaf child is the same as the general population's chance of 1 in 1000,
as suspected based on the clinical information, or whether that chance is
actually 50%. In addition, without molecular testing, there is no way to
know prior to M.S.'s having children whether she has inherited a gene
from her father for high-frequency hearing loss. This case also addresses the
issue of deaf people's perceptions of their chance to have deaf children and
their desires to have deaf or hearing children, which vary greatly from
individual to individual.
6.2 Case 2
S.K. is a 23-year-old, profoundly deaf, white female who is self-referred to
learn more about why she is deaf and why she has different colored eyes.
She was born deaf and attended residential schools for the deaf for most
of her life. S.K. currently is not married and does not plan to have children
in the near future, although she is curious about her chance to have deaf or
hearing children, should she decide to have children in the future.
