Dwarfism

the long and the short of it

A Brief Summery

Dwarfism is a medical condition that can be caused by a medical or genetic condition where individuals only reach an adult height of 4 feet 10 inches or less. Dwarfism occurs in one out of every 40,000 births. There is no racial, ethnic or gender factor to the condition, but its prevalence does increase in older parents, especially fathers.

Famous People with Dwarfism

Verne Troyer

Verne Troyer is an actor who has played roles including Mini-Me in the Austin Powers movies

Kenny Baker

Kenny Baker is an actor who is best-known as R2-D2 in all of the Star Wars films.

Peter Dinklage

Peter Dinklage is an actor who is well known for his role in the Game of Thrones. He also had a role in the movie Pixels.

Hervé Jean-Pierre Villechaize






Hervé Jean-Pierre Villechaize was a French actor who was best known for his role as Mr. Roarke’s assistant in the long running television show, Fantasy Island. He also played an evil henchman in the James Bond film, The Man with the Golden Gun.

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Disease Symptoms and Biology of Disease

Dwarfism disorder typically causes people to be disproportionately short (adults around 4 feet). In many cases the person has an average-size trunk and very short limbs. There are variations where people have a very short trunk and disproportionately large limbs). In these cases, the heads are typically large compared to the body. Most people with disproportionate dwarfism are intellectually normal.


The following are common features:


  • Average adult height around 4 feet
  • Average-size trunk
  • Short arms and legs. Short upper arms and legs
  • Disproportionately large head. Prominent forehead. Flattened bridge of the nose
  • Short fingers. A wide separation between the middle and ring fingers
  • Limited elbow mobility
  • Bowed legs
  • Swayed lower back


Over 99% of cases of achondroplasia (short-limbed dwarfism) is caused by two mutations in the FGFR3 gene. Both of these mutations cause an amino acid (protein building block) glycine to be replaced with arginine at protein postion 380. It is written as Gly380Arg or G380R. It is generally believed that it is causes the receptors to be overly active. This leads to bone growth disturbances.

FGFR3

The FGFR3 gene tells the system how to create a protein called fibroblast growth factor receptor 3. Its family of four fibroblast growth factor receptors are important in the regulation of cell growth and division, formation of blood vessels, and embryo development

Diagnosis/Treatment/and Ethical Implications

There are many indicators that hint towards dwarfism. These include:


 Measurement – Doctors typically measure height, weight and head circumference as part of


well-baby visits. If these values are trending beyond typical percentile rankings, it can be a


strong indicator.


 Appearance – Pediatricians may identify distinctive facial and skeletal features that are common


with dwarfism.


 Imaging technology –X-rays may be useful in identifying certain abnormalities. These


abnormalities of the skull and skeleton can help identify the disorder. MRIs may be used to


reveal pituitary gland or hypothalamus abnormalities. These can play a role with the hormone


function.


 Family History - Since it is genetic, a family history may be a good indicator.


 Genetic Testing – There are currently genetic tests for many of the known dwarfism genes. In


most cases, these tests are not given, since dwarfism is easily identified using simpler tests.


Once diagnosed. Dwarfism can’t generally be cured. Unfortunately, dwarfism often comes with


numerous associated problems. Many treatments are done to reduce these problems. These include:


 Relieving pressure on the brain by inserting shunts to drain excess fluid


 Surgeries are often conducted to correct bone direction.


 Expand small airways with a tracheotomy


 Fix bowed legs, club foot, and cleft palates with corrective deformity surgeries


 It is common to have tonsils that are disproportionate to small heads. This is often fixed by


removing tonsils and adenoids


 Spinal cord compression is often fixed with surgery to widen the spinal canal.


 Physical therapy is often used for strengthen muscles and increase range of motion.


 Back braces are often used to help with curvature of the spine.


 Draining tubes are often used to prevent hearing loss due to ear infections.


 Small jaws often cause teeth crowding. This is fixed with orthodontics.


 In people where dwarfism is caused by hormonal deficiencies, doctors may treat the patients


with synthetic hormones. This can include daily injections for years and is somewhat


controversial.


 Obesity is often avoided with special diet and exercise.


One of the more controversial surgeries that some people choose is extended limb lengthening. This is


a series of surgeries that can be done as a person with dwarfism grows. This surgery has multiple risks


and can be physically and emotionally draining. It is therefore recommended that it be delayed until the


person being operated on is old enough to decide to have the surgery.

Type of Mutation and Type of Inheritance

Achondroplasia dwarfism is an autosomal dominant pattern inherited trait. This means that a copy of the altered gene in each cell is enough to cause the disorder. As much as 80% of people with dwarfism have an average sized parent. In these cases, a new mutation in the FGFR3 gene is created. In the remaining 20%, the gene is inherited from one or both affected parents. When a person inherits altered genes from both parents, it is common to have a severe form of dwarfism that includes an underdeveloped rib cage and extremely shortened bones. Many of these individuals are stillborn or die shortly after birth of respiratory failure.

References

Children’s Health: Dwarfism. (2005). Retrieved from http://www.webmd.com/children/dwarfism-causes-treatments?page=3

Diseases and Conditions Dwarfism. (1998). Retrieved from http://www.mayoclinic.org/diseases-conditions/dwarfism/basics/definition/con-20032297

Dwarfism. (2016). Retrieved from http://www.healthofchildren.com/D/Dwarfism.html

Dwarfism: How is Primordial dwarfism Inherited? (n.d.). Retrieved from http://dwarfism.weebly.com/how-is-premordial-dwarfism-inherited.html

Genetics Home Reference: Dwarfism. (June 2013). Retrieved from https://ghr.nlm.nih.gov/gene/FGFR3

Genetics Home Reference Guide: Achondroplasia. (May 2012). Retrieved from https://ghr.nlm.nih.gov/condition/achondroplasia

Learning About Achondroplasia. (2012). Retrieved from https://www.genome.gov/19517823

SANGHAVI, D. M. (2006, December 5). Wanting Babies Like Themselves, Some Parents Choose Genetic Defects. The New York Times. Retrieved from http://www.nytimes.com/2006/12/05/health/05essa.html?_r=0