Dwarfism is when a person is short in stature because of their genes or a medical reason. It’s defined by the advocacy groups Little People of the World Organization (LPOTW) and Little People of America (LPA) as an adult height of 4 feet 10 inches or under, as a result of a medical or genetic condition. Other groups extend the criteria for certain forms of dwarfism to 5 feet, but the average height of an adult with dwarfism is 4 feet.
There are two main categories of dwarfism -- disproportionate and proportionate.
Disproportionate dwarfism is characterized by an average-size torso and shorter arms and legs or a shortened trunk with longer limbs.
In proportionate dwarfism, the body parts are in proportion but shortened.
Dwarfism Symptoms
In addition to short stature, dwarfism has many other symptoms that can vary depending the type it is.
Disproportionate dwarfism symptoms
Disproportionate dwarfism usually doesn’t affect intellectual development unless a child has other rare conditions, including hydrocephalus, or excess fluid around the brain.
Symptoms of disproportionate dwarfism may include:
Adults typically are about 4 feet tall
Average-size torso and very short limbs, especially in the upper halves of arms and legs
Short fingers
Wide spaces between the middle and ring fingers
Limited elbow mobility
Disproportionately large head
Prominent forehead
Flattened bridge of the nose
Bowing of legs that progressively worsens over time
Swaying of the back that progressively worsens over time
Some people with disproportionate dwarfism have a rare disorder called spondyloepiphyseal dysplasia congenita (SEDC). Adults with SEDC are around 3 to 4 feet tall and may have these signs too:
Very short trunk
Short neck, arms, and legs, but average-size hands and feet
Broad chest
Flattened cheekbones
Cleft palate, or an opening in the roof of the mouth
Proportionate dwarfism is caused by a medical condition you have at birth or that develops in childhood that hinders growth and development. One common cause is too-low amounts of growth hormone produced by your pituitary gland.
Symptoms of proportionate dwarfism include a smaller head, arms, and legs. But all are in proportion with each other. Organ systems may be smaller too.
Other signs of proportionate dwarfism in children are:
Slower growth rate than expected for their age
Height lower than the third percentile on standard charts for age
Delayed or no sexual development during the teen years
Related:
Dwarfism Causes
There are approximately 400 types of dwarfism. Causes of proportionate dwarfism include metabolic and hormonal disorders such as growth hormone deficiency.
The most common types of dwarfism, known as skeletal dysplasias, are genetic. Skeletal dysplasias are conditions of abnormal bone growth that cause disproportionate dwarfism.
They include:
Achondroplasia. The most common form of dwarfism -- accounting for 70% of cases -- achondroplasia occurs in about one out of 26,000 to 40,000 babies and is evident at birth. People with achondroplasia have a relatively long trunk and shortened upper parts of their arms and legs. Other features of achondroplasia include:
Spondyloepiphyseal dysplasias (SED).A less common form of dwarfism, SED affects approximately one in 95,000 babies. Spondyloepiphyseal dysplasia refers to a group of conditions characterized by a shortened trunk, which may not become apparent until a child is between ages 5 and 10. Other features can include:
Early diagnosis and treatment can help prevent or lessen some of the problems associated with dwarfism. People with dwarfism related to growth hormone deficiency can be treated with growth hormone. For children five years of age and older with achondroplasia who still have the potential for growth, the FDA has approved vosoritide (Voxzogo) to help stimulate bone growth.
In many cases, people with dwarfism have orthopaedic or medical complications. Treatment of those can include:
Insertion of a shunt to drain excess fluid and relieve pressure on the brain
A tracheotomy to improve breathing through small airways
Corrective surgeries for deformities such as cleft palate, club foot, or bowed legs
Surgery to remove tonsils or adenoids to improve breathing problems related to large tonsils, small facial structures, and/or a small chest
Surgery to widen the spinal canal (the opening through which the spinal cord passes) to relieve spinal cord compression
Extended limb lengthening, a controversial surgery, due in part to its risks, involves several procedures. It is only done on adults.
Dwarfism Diagnosis
Some forms of dwarfism are evident in utero, at birth, or during infancy and can be diagnosed through X-rays and a physical exam. A diagnosis of achondroplasia, diastrophic dysplasia, or spondyloepiphyseal dysplasia can be confirmed through genetic testing. In some cases, prenatal testing is done if there is concern for specific conditions.
Sometimes dwarfism doesn't become evident until later in a child's life, when dwarfism signs lead parents to seek a diagnosis. Here are signs and symptoms to look for in children that indicate a potential for dwarfism:
A larger head
Late development of certain motor skills, such as sitting up or walking