Facts about Dwarfism
There are over 200 skeletal dysplasia (abnormal bone growth) disorders resulting in short stature or dwarfism. (1) A boy born with dwarfism will grow to an average height of 4 foot 4 inches, and a girl, 4 foot 1 inch. (2)
The two main types of dwarfism are disproportionate dwarfism, where a person has an average-sized trunk and short arms and legs, or shortened trunk and disproportionately long arms and legs, and proportionate dwarfism, where no one body part is too small or too large. (1)
Forms of Dwarfism
The most common form of dwarfism is achondroplasia and accounts for one out of every 25,000 births. (2, 3)
Babies born with achondroplasia don’t convert cartilage to bone as they grow (4) and can display:
• Moderate to marked short stature (sometimes as small as 3 feet 8 inches)
• Large heads
• Constriction of the craniocervical junction where the skull and neck join, and where the spinal cord connects with the brain through a large hole (foramen magnum)
• Short fingers with longer space between the middle and ring fingers
• Joint hypermobility
• Low nasal bridge and narrow nasal passages
• Enlargement of the brain (megalencephaly)
• Obstructive sleep apnea (ages 2 to 10)
• Recurrent or persistent middle ear dysfunction with hearing loss
• Kyphosis or hunching of the upper back
• Arching of the lower back (hyperlordosis)
• Limited elbow extension (only 20 to 60 degrees)
• Hypermobility of the wrists
• Knock-knees and/or bowed legs (about 60-80 percent of children)
(3)
Most babies born with this form of dwarfism have normal life expectancy and cognitive abilities.
Other Forms of Dwarfism5
Other forms of dwarfism include:
• Spondyloepiphyseal dysplasia (SED)
One in every 95,000 babies is born with SED, although it may not be really noticeable until the child is between 5 and 10 years of age. Children with SED may also have club feet, cleft palate, severe osteoarthritis in the hips, weak hands and feet, and barrel-shaped chest.
• Diastrophic dysplasia
This affects one in every 100,000 births and is characterized by shortened forearms and calves. Babies with this form of dwarfism can also have deformed hands and feet, limited range of motion, cleft palate, and ears with a cauliflower appearance. (5)
SED and Diastrophic dysplasia are caused by recessive genes passed on from both parents. Achondroplasia occurs when only one dominant gene is passed from either the mother or the father.
“Often parents of children with achondroplasia do not carry the mutated gene themselves. The mutation in the child occurs spontaneously at the time of conception.” (5)
Sources:
1. Dwarfism: Symptoms. Mayo Clinic. Web. Mar 29, 2012.
http://www.mayoclinic.com/health/dwarfism/DS01012/DSECTION=symptoms
2. “Achrondroplasia” by Melissa Conrad Stöppler, MD. MedicineNet.com. Web. Mar 19, 2012.
http://www.medicinenet.com/achondroplasia/article.htm
3. “Achondroplasia: Natural History in the Infant and Young Child” by Richard M. Pauli, M.D., Ph.D., Midwest Regional Bone Dysplasia Clinics. Web. Mar 19, 2012.
http://data.memberclicks.com/site/lpa/NH%20achondroplasia.pdf
4. Dwarfism. Shriners Hospital for Children. Web. Mar 19, 2012.
http://www.shrinershospitalsforchildren.org/CareAndTreatment/Orthopaedics/Dwarfism.aspx
5. Children's Health: Dwarfism. WebMD. Web. Mar 19, 2012.
http://children.webmd.com/dwarfism-causes-treatments
Reviewed August 28, 2012
by MIchele Blacksberg RN
Edited by Jody Smith