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Complex Traits

Author(s): Nancy Moreno, PhD.

Screening for Health Problems

Procedure (cont.)

4. This slide describes a disease mutation in Dalmatians and other breeds, such as Bulldogs. The mutation predisposes dogs to developing painful stones in their bladders or kidneys, and is related to similar human diseases. The disease can be managed through diet or medications, but sometimes surgery is necessary to remove the stones. Because of selective breeding for desirable characteristics, the disease trait also was incorporated into 100% of Dalmatians. In other words, all Dalmatians have two copies (homozygous) of the kidney stone (hyperurcosuria) allele, which is recessive. A breeding program was created to introduce the normal allele back into the breed. However, this action has generated considerable controversy among breeders, owners and kennel clubs, which register purebred dogs, and many organizations do not recognize the dogs without the disease allele as “pure” Dalmatians. 

5. Students may have many questions about the implications of the genetic conditions shown in the slides. Tell students, Gene mutations are common in all living organisms. Most of these mutations do not affect the health or appearance of the individual. In some cases, however, mutations confer a benefit—in other cases, they cause a deformity or increase the likelihood that the individual will develop an illness.

6. Next, explain to students that they are going to learn more about how genome science is advancing the understanding of diseases, but also is creating new kinds of questions. More than 1,000 genetic tests are available for use with dogs—these tests identify gene alleles related to color, size, and disease traits, among many others, including the traits we have just seen. The availability of genetic testing provides opportunities to improve health, but also raises many ethical questions. We will examine these questions from different points of view.

Funded by the following grant(s)

Science Education Partnership Award, NIH

Gene U: Inquiry-based Genomics Learning Experiences for Teachers and Students
Grant Number: 5R25OD011134

Robert Wood Johnson Foundation

Using Learning Technology to Build Human Capital
Grant Number: 57363