What Are the Different Types of Skeletal Dysplasia and Dwarfism?
In general, the disorders are divided into two categories:
Proportionate Dwarfism
Proportionate dwarfism is when a person’s body parts are in proportion but shortened. This is often due to metabolic and hormonal disorders such as a deficiency in the human growth hormone.
A person may have a head, limbs, and trunk that are short but still proportionate to one another. This type of dwarfism can affect other parts of the body, like the heart. Proportionate dwarfism is often caused by another medical condition that limits growth and development. One of the most common causes is growth hormone deficiency—a condition where a child’s pituitary gland doesn’t produce enough growth hormone to help the body grow.
Disproportionate Dwarfism
Disproportionate dwarfism is when a person has body parts that are not proportionate to each other—they can be several different sizes. In most cases, the trunk is average-sized and the limbs are short. However, it’s also possible that a person could have a very short trunk, and limbs that are technically “short” but appear large compared to the trunk.
The most common types and symptoms of disproportionate dwarfism:
Achondroplasia
Achondroplasia is the most common type of dwarfism, causing about 70% of cases. It occurs when cartilage – the tissue that makes up most of a fetus’s skeleton during development – doesn’t convert to bone the way normal cartilage does resulting in a usually normal torso and shortened limbs.
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Spondyloepiphyseal Dysplasia Congenita (SEDc)
SEDc is a rare genetic disorder that results in short stature and skeletal abnormalities that primarily affect the spine and long bones of the arms and legs.
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Diastrophic Dysplasia
Diastrophic dysplasia is a disorder that affects the body’s ability to form cartilage and bone development and results in short stature, joint and hand deformities, and abnormal curving of the spine.
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Pseudoachondroplasia
Pseudoachondroplasia is a rare form of dwarfism that affects bone grown. Children with pseudoachondroplasia have a normal head size, facial features and intelligence level. However, they are small in stature.
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Hypochondroplasia
Hypochondroplasia is a form of short-limbed dwarfism. Like other forms of dwarfism, it occurs when a fetus is still in the womb and there is a problem related to the cartilage converting into bone. It is considered a milder form of dwarfism.
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Turner Syndrome
Turner syndrome is a type of dwarfism that only affects females. In addition to being short in stature, girls with Turner syndrome often have heart defects and their ovaries do not develop normally. Often girls with Turner syndrome grow normally, then around age 5 their growth slows and their short stature becomes noticeable.
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