Dwarfism

If your child has been diagnosed with dwarfism, you're probably wondering what lies ahead for her and your family. You may be asking if your child will lead a normal life, or perhaps you're concerned about the challenges she'll face growing up with below-average height.

It may be comforting to know that your family is not alone. Although estimates vary, between one in 14,000 and one in 27,000 babies are born each year with some form of dwarfism. Many people with dwarfism and their families belong to active social and support groups for people of short stature. To learn more about the condition and living with dwarfism, read on.

What Is Dwarfism?
Dwarfism describes an unusually short stature that can arise from a variety of genetic and other conditions. The Little People of America, one of the largest and most active support groups for people with dwarfism, considers dwarfism to be an adult height of 4 feet 10 inches or less.

Many types of dwarfism are skeletal dysplasias , conditions marked by abnormal bone growth. They are divided into two types: short-trunk and short-limb dysplasias.

People with short-trunk dysplasia have a shortened trunk with relatively longer limbs, whereas those with short-limb dysplasia have a near-normal size trunk but small arms and legs. Both types cause disproportionate short stature , which means that the parts of the body are not in proportion to one another: some parts are approximately average size, whereas others are significantly shorter.

In the past, the terms "dwarfism" and "dwarf" were only used to refer to these cases of disproportionate short stature. The term "midget" was usually applied to conditions of proportionate short stature , in which all parts of the body match in size. However, the word "midget" now is considered offensive by many people of short stature and has fallen into disuse. Today the term "dwarf" also takes a back seat to "little person," "person of short stature," or "person with dwarfism." Just like anyone else, though, people of short stature most like to be known by their names instead of any identifying characteristics like dwarfism.

What Causes Dwarfism?
More than 200 recognized conditions cause dwarfism. Most of them are genetic , resulting from either a spontaneous genetic change (or mutation) or genes inherited from one or both parents. In cases of both spontaneous mutation and inherited genes, two average-size parents can have a child with short stature. In fact, 85% of children with achondroplasia, the most common form of dwarfism, are born to average-size parents. Dwarfism occurs in all ethnic groups.

In instances of spontaneous genetic change, a single normal gene in a chromosome that a parent passes to the child suddenly changes (mutates) in such a way that it brings about that specific condition. Scientists do not yet know what prompts the genes to undergo that change.

Inherited conditions, on the other hand, are carried by one or both parents in their genes - they are a part of the parent's genetic makeup instead of a sudden mutation.

Spontaneous mutation can occur in any pregnancy and is the more frequent cause of a child with dwarfism being born to average-size parents. However, if both parents carry a recessive gene for a particular condition that produces dwarfism (meaning they possess the gene that causes the condition but do not actually have the condition themselves), and they both pass that gene to their child, the child would be of short stature.

By far the most common causes of dwarfism are the skeletal dysplasias, including:

Achondroplasia is a form of short-limb dwarfism caused by a single autosomal dominant gene. That means a spontaneous mutation in this one gene can produce the condition or a child can inherit the gene from a parent who has achondroplasia. People with achondroplasia have a relatively long trunk and shortened upper parts of their arms and legs (the parts connected to the shoulders and hips), known as rhizomelic shortening of the limbs.

People with diastrophic dysplasia , another form of short-limb dwarfism, can have shortened upper or middle sections (the forearms and calves) of their arms and legs; the latter is known as mesomelic shortening. Significant bowing of the legs further reduces their height. Doctors originally thought diastrophic dysplasia was a variation of achondroplasia, but it has come to be recognized as a distinct condition with its own characteristics.

The spondyloepiphyseal dysplasias are a very large group of skeletal conditions that cause short-trunk dwarfism. They are distinguished by abnormal growth in the spine and long bones of the body, which leads to a short trunk. In one form of SED, spondyloepiphyseal dysplasia tarda, the lack of growth in the trunk may not become apparent for several years, until the child is between 5 and 10 years old. By contrast, children with spondyloepiphyseal dysplasia congenita have a short neck and trunk, with a barrel-shaped chest, at birth.

Unlike the skeletal dysplasias, which largely produce disproportionate forms of dwarfism, proportionate types of dwarfism usually result from metabolic or hormonal disorders in infancy or childhood. Chromosomal abnormalities, pituitary gland disorders (which influence growth and metabolism), absorptive problems (when the body can't absorb nutrients adequately), malnutrition,failure to thrive , and kidney disease can all lead to short stature if the child fails to grow at a normal rate.