Parents who suspect that their child may have a genetic disorder have a new tool in their physician's diagnostic arsenal. One British physician has improved on an old practice of examining a person's face to look for traits that come from genetic disorders.
It's true. The shape of your face, along with certain facial characteristics, can be a sign that you suffer from a genetic disorder. As many as 17,000 genetic disorders have been diagnosed [source: Deccan Herald]. Around 700 of these diagnosed disorders display abnormal facial characteristics [source: Daily Mail]. A classic example is the genetic disorder Down syndrome. This condition occurs when children inherit an extra copy of chromosome 21, giving them 47 chromosomes, rather than the usual 46. Doctors can easily diagnose Down syndrome due to the unique facial and cranial characteristics associated with it. But what about rarer disorders?
Dr. Peter Hammond created a computer program to make diagnosing some of these rare disorders easier. The program provides an accurate diagnosis, which can help parents make better decisions about treatment and genetic counseling for their child.
Dr. Hammond spent the last seven years traveling the globe collecting images of people with genetic disorders and entering them into a database he compiled. The program takes photos of children who share a genetic disorder, usually a series of 30 to 50, and creates a three-dimensional composite image for that disorder. When a physician encounters a suspected genetic disorder that has him stumped, he can introduce a photo of his patient into Hammond's database. The program examines facial traits, like the distance between eyes and the width of the nose, and compares traits found in the patient's image to those of the composites and comes up with possible diagnoses. As a control, Hammond also fed into his database images of children without a genetic disorder, creating a composite of a "normal" child.
For 30 of the 700 facially characteristic disorders, Hammond's program offers around 90 percent accuracy in diagnosis. These are generally the most easily recognizable conditions, such as Williams syndrome. People who suffer from this genetic disorder have short, upturned noses and mouths, along with a small jaw and a large forehead.
Williams syndrome is pretty rare -- some studies say it occurs in one out of every 7,500 births, while others say it's one in 10,000 births [source: OMIM]. But other genetic disorders are even rarer. For a doctor faced with a baffling condition that he has not encountered before, Hammond's program offers a chance to narrow the field. Determining which genes are associated with the possible diagnoses cuts down on the number of tests required to pinpoint the disorder. This can be important for worried parents who want to know what their child suffers from, as genetic tests can cost hundreds or thousands of dollars each [source: Science Direct].
Hammond's database has already discovered a new characteristic in autistics that can be used to diagnose autism spectrum disorder. The program found a "lopsided" effect in autistic people -- the result of one side of the brain being larger than the other side. The inventor-physician says he plans to further hone his database to be able to include factors like race and gender [source: BBC].
While his work is definitely furthering the field of medical diagnosis of genetic disorders, Hammond is actually building on an old foundation. Read on to find out about dysmorphology, the study of physical characteristics to diagnose disorders, as well as genetic counseling.
The Human Genome Project completed mapping of the genetic sequencing of human DNA in 2005. One discovery the 15-year investigation of genetics turned up is that just about every disease we are aware of has some sort of genetic factor associated with it [source: National Human Genome Research Institute].
Diseases can be the result of a variant gene passed down from parents, a mutation occurring on a gene, or one of these two factors working in conjunction with environmental factors, like smoking or poor eating habits. It's not possible for a physician to examine the external physical characteristics of a patient to determine if he has attention-deficit hyperactivity disorder (ADHD) or insomnia. But factors such as ADHD and trouble sleeping, combined with a study of physical characteristics, can help doctors in diagnosing genetic disorders.
This study of physical characteristics is called dysmorphology. Dysmorphology is based on an established set of average physical traits. By using these touchstones, physicians can determine whether a patient is displaying the physical characteristics associated with a genetic disorder. For example, eye slits are expected to be horizontal. Depending on the horizontal orientation of a patient's eye slits, say downward towards the nose, a doctor can get a good idea of what kind of disorder he is dealing with.
Other measurements that are examined in dysmorphology and were considered in Hammond's composite database include the distance between the eyes, the width of the bridge of the nose, the size of the chin and the length of the forehead.
While Hammond's programs and dysmorphology can help diagnose genetic disorders using facial characteristics, both are useful only after a person has already begun to develop physically. There are only a handful of genetic disorders that can be treated -- usually through drug therapy. Some genetic disorders that display facial characteristics also come with other, internal problems. People with Williams syndrome, for example, usually also have heart conditions. A swift diagnosis through Hammond's program can see to it that these less-obvious conditions be addressed and treated earlier rather than later.
Genetics has also produced another field, genetic counseling, which seeks to prevent genetic disorders. Through genetic counseling, parents who have or carry genetic disorders can determine the likelihood that they will pass on their mutation to their children.
In addition to being dominant, genes can be recessive, meaning defects in their structure that can lead to genetic diseases don't appear in the person carrying them. Once they're passed along, however, some circumstances -- like gender or a mate who submits another copy of the recessive gene -- can cause the gene to become dominant, appearing in the children. In this sense, genetic counseling can be a good idea for all parents. It is recommended most strongly for parents who suffer from a genetic disorder, who have already produced children with a genetic disorder, or spouses in a consanguineous marriage -- a marriage between blood relatives.
While Hammond's database and dysmorphology in general are benign in nature, genetic counseling does have the potential to become a slippery slope. While parents who become knowledgeable about their own genes and their genes' potential for producing healthy offspring can make better-informed decisions about reproducing, pushed to its extreme, genetic counseling approaches eugenics -- the quest to perfect the human race by eliminating undesirable traits.
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More Great Links
- Brice, Dr. Phillippa. "Facial Scans Could Aid Diagnosis of Rare Genetic Disorders." PHG Foundation. September 11, 2007. http://www.phgfoundation.org/news/3668/
- Hegde, Dr. Sridevi. "Hidden Within Your Genes." Deccan Herald. September 15, 2007. http://www.deccanherald.com/Content/Sep152007/living2007091425460.asp
- Highfield, Roger and Fleming, Nic. "Face Can Help Diagnose Rare Genetic Disorders." The Telegraph. September 9, 2007. http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/09/10/sciface110.xml
- Macrae, Fiona. "Facial Scans Could Reveal Genetic Disorders." Daily Mail. September 10, 2007. http://www.dailymail.co.uk/pages/live/articles/health/healthmain.html?in_article_id=480952&in_page_id=1774&in_a_source
- Morelle, Rebecca. "3D Face Scans Spot Gene Syndromes." September 9, 2007. http://news.bbc.co.uk/2/hi/science/nature/6982030.stm
- "3D Face Scan Helps Detect Genetic Disorders." Blood Index Times. September 10, 2007. http://www.bloodindex.org/view_news_zone.php?id=1004
- "Basic Dysmorphology." University of South Dakota. http://www.usd.edu/med/som/genetics/curriculum/2EDYSMO5.htm
- "Frequently Asked Questions About Genetic Disorders." National Human Genome Research Institute. http://www.genome.gov/pfv.cfm?pageID=19016930