| Inheritance | X-linked recessive |
|
Occurrence
|
not really known-- may be as high as 7 in 10,000 (The Encyclopedia of Birth Defects) |
| Description | a group of disorders characterized by the absence of sweat glands, abnormal teeth, and hypotrichosis (less hair than normal) |
| Gene | located on the X chromosome, produces a 135 amino acid protein -- little else is known |
Background:
This disorder can be used when discussing our bodies' cooling mechanisms. One interesting side note with this disorder is that women who are carriers for this often exhibit "Lyonization." This means that although they do not suffer all of the effects, they have a few of the traits. Carriers often have patchy areas where they do have sweat glands and other areas where they do not. These areas with sweat glands and without sweat glands appear in definite patterns. Generally they exhibit v-stripes across the back. One way to diagnose a carrier is to perform a sweat test on a suspected individuals back. If the sweat glands appeaar in definite striped patterns, then the individual is a carrier. Carriers may also exhibit missing or malformed teeth.
Activity:
Our body has a magnificent way to maintain our body temperature -- sweat. Have the class get into groups and discuss the ways sweat works to maintain body temperature. Ask students to hypothesize how they would be affected if they did not have sweat glands. Then introduce them to this disorder. Individuals with anhidrotic ectodermal dysplasia must be very careful not to overheat, since they have no way to cool themselves off naturally. Historically individuals with this disorder were known to jump into lakes or carry around buckets of cold water to pour over them in the event they began to overheat. There are still few treatments available to avoid overheating besides air conditioning and limited physical activity.
For more information visit Online Mendelian Inheritance in Man or HED (hypohidrotic ectodermal dysplasia) Foundation
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