Campomelic Dysplasia

Campomelic dysplasia is one of the more rare forms of congenital short-limb dwarfism. Its incidence is approximately 1 in 111,000 to 1 in 200,000 live births. The term "campomelic" or "camptomelic" is of Greek origin and literally means "bent limb."

 
How Campomelic Dysplasia Is Inherited

Campomelic dysplasia is typically inherited in a sporadic, autosomal dominant manner (3).

 
Causes of Campomelic Dysplasia

Campomelic dysplasia is caused by a mutation in the SOX-9 gene, localized to chromosome 17. The SOX-9 gene encodes for a transcription factor that is responsible for normal cartilage development and sexual development.

 
Physical Characteristics

Campomelic dysplasia is characterized by the bowing of the femur and tibia. Some individuals can have this condition without any appreciable bowing of the long bones but with other major features. These patients are referred to as having "acampomelic" camptomelic dysplasia. We will limit the following discussion to patients with classic campomelic dysplasia.

Campomelic dysplasia can be a lethal condition. However, a proportion of campomelic children can survive into adulthood. In the newborn period, respiratory distress may occur due to the lack of development of the cartilage rings that support the tracheobronchial tree. Although respiratory insufficiency may lead to hypoxic brain injury, in general patients with campomelic dysplasia have average intelligence.

Face & Skull:
  • Long and narrow skull
  • Prominent forehead
  • Flat face with a depressed nasal bridge
  • Micrognathism
  • Possible cleft palate
Trunk, Chest, & Spine:
  • Short neck with redundant skin at the nape of the neck
  • Small, narrow, and bell-shaped chest
  • Eleven pairs of ribs
  • Protuberant abdomen
Arms & Legs:
  • Anterior bowing of the femur and tibia.
  • A deep subcutaneous dimple over the most prominent aspect of
    the tibia.
  • Clubfeet, frequently present on both sides.
What are the X-ray characteristics?

The radiological features of campomelic dysplasia include bowing of the femur and tibia. Typically, patients exhibit delayed ossification of distal femoral and proximal tibial epiphyses. Radial heads are dislocated. Widely spaced vertical ischia and a hypoplastic pubic bone are seen in the pelvis. Vertebral pedicles are hypoplastic or nonmineralized. Cervical vertebrae are hypoplastic. The thorax is small and bell-shaped, with eleven ribs, appearing wavy and thin. The first metacarpals are short. Short middle phalanges of the second through fifth fingers are also typical (4).

 
Musculoskeletal Problems
Long Bone Bowing

Long bone bowing in campomelic dysplasia is variable. Corrective osteotomies of the femur and tibia should be performed so that the child can start standing and walking at the appropriate times. The timing of such surgery is influenced by the child’s respiratory status. Developmental milestones are delayed in campomelic dysplasia and this should be kept in mind during decision making. A period of casting is necessary in the immediate post-operative period, followed by long-term bracing to maintain correction.

Hip Dislocations

Congenital/developmental hip dislocations are typically managed along standard lines. In infancy, the mainstay of treatment is by means of a Pavlik harness. If this fails, surgery becomes necessary.

Cervical kyphosis is an initial problem, secondary to failure of formation of the anterior cervical vertebral bodies, which can lead to spinal cord compression. Thoracic kyphoscoliosis is a severe problem that may require surgery.

Clubfeet

Clubfeet should be treated along standard lines with corrective casting and surgery, depending upon the severity of the problem.

 
Problems Elsewhere in the Body
Tracheobronchial Tree

The most significant abnormality in campomelic dysplasia is the lack of development of the cartilage rings supporting the trancheobronchial tree. These cartilage rings normally keep the breathing passages open. Poor cartilage development may cause the collapse of these passages, producing extremely small airways and causing respiratory insufficiency.
At birth, the child may require a tracheostomy and long-term ventilation
at home for the first few years of life. Many do not survive past the neonatal period.

Congenital Heart Defects

Congenital heart defects were found in around 25% of cases. The most common anomaly is a patent ductus arteriosus or patent foramen ovale.
An echocardiogram should be done to evaluate for possible congenital heart disease.

Genitourinary Tract

Genitourinary Tract: Hydronephrosis (enlarged kidney), bilateral ureteral dilatation are seen in 1/3 of patients. Hypoplastic cystic kidney, renal hypoplasia, ureteral stenosis, and renal calculi have been described in the literature. These do not pose major health risks initially but require monitoring by a nephrologist/urologist in the long-term.

Sex Reversal

Some phenotypic females may genetically be males.

Hearing

Recurrent middle ear infections, poor development of bones that normally conduct sound (auditory ossicles) and abnormal skull shape are some of the factors that contribute to hearing loss. Any suspicion of hearing loss or recurrent ear infections should prompt referral to an ENT surgeon/ audiologist for further investigation.

 
What to Watch For
  • Respiratory distress in the newborn period.
  • Chromosomal analysis should be done to evaluate for possible sex reversal in phenotypic females.
  • A renal-pelvic ultrasound should be done to assess any anomalies of the genitourinary tract.
  • Cervical spine instability due to possible cervical kyphosis.
 
References
  1. Jones, Kenneth L. Recognizable Patterns of Human Malformation. Philadelphia, PA: Elsevier Saunders. 2006.
  2. Norman, EK. Pedersen, JC. Stiris, G. Van der Hagen, CB. 1993. Campomelic dysplasia-an underdiagnosed condition? European Journal of Pediatrics. 152: 331-333.
  3. Scott, Charles I. Dwarfism. Clinical Symposium, 1988; 40(1):21-24.
  4. Spranger, Jurgen W. Brill, Paula W. Poznanski, Andrew. Bone Dysplasias: An Atlas of Genetic Disorder of Skeletal Development. Oxford: Oxford University Press. 2002.

Trusted Insights from Nemours' KidsHealth

Dwarfism

There's been a lot of discussion over the years about the proper way to refer to someone with dwarfism. Many people who have the condition prefer the term "little person" or "person of short stature." For some, "dwarf" is acceptable. For most, "midget" definitely is not.

But here's an idea everyone can agree on: Why not simply call a person with dwarfism by his or her name?

Being of short stature is only one of the characteristics that make a little person who he or she is. If you're the parent or loved one of a little person, you know this to be true.

But here are some facts that other people may not realize about dwarfism and those who have it.

Dwarfism:

  • is characterized by short stature. Technically, that means an adult height of 4 feet 10 inches or under, according to the advocacy group Little People of America (LPA).
  • can be caused by any one of more than 300 conditions, most of which are genetic. The most common type, accounting for 70% of all cases of short stature, is called achondroplasia.
  • can and most often does occur in families where both parents are of average height. In fact, 4 out of 5 of children with achondroplasia are born to average-size parents.

Dwarfism isn't:

  • an intellectual disability. A person who has dwarfism is typically of normal intelligence.
  • a disease that requires a "cure." Most people with one of these conditions live long, fulfilling lives.
  • a reason to assume someone is incapable. Little people go to school, go to work, marry, and raise children, just like their average-size peers.

What Causes Short Stature?

More than 300 well-described conditions are known to cause short stature in a child. Most are caused by a spontaneous genetic change (mutation) in the egg or sperm cells prior to conception. Others are caused by genetic changes inherited from one or both parents.

Similarly, depending on the type of condition causing the short stature, it is possible for two average-size parents to have a child with short stature, and is also possible for parents who are little people to have an average-size child.

What prompts a gene to mutate is not yet clearly understood. The change is seemingly random and unpreventable, and can occur in any pregnancy. If parents have some form of dwarfism themselves, the odds are much greater that their children will also be little people. A genetic counselor can help determine the likelihood of passing on the condition in these cases.

Dwarfism has other causes, including 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), and kidney disease can all lead to short stature if a child fails to grow at a normal rate.

Types of Short Stature

Most types of dwarfism are known as skeletal dysplasias, which are conditions of abnormal bone growth. They're divided into two types: short-trunk and short-limb dysplasias. People with short-trunk dysplasia have a shortened trunk with more average-sized limbs, whereas those with short-limb dysplasia have an average-sized trunk but shortened arms and legs.

By far, the most common skeletal dysplasia is achondroplasia, a short-limb dysplasia that occurs in about 1 of every 15,000 to 40,000 babies born of all races and ethnicities. It can be caused by a spontaneous mutation in a gene called FGFR3, or a child can inherit a change in this gene from a parent who also has achondroplasia.

People with achondroplasia have a relatively long trunk and shortened upper parts of their arms and legs. They may share other features as well, such as a larger head with a prominent forehead, a flattened bridge of the nose, shortened hands and fingers, and reduced muscle tone. The average adult height for someone with achondroplasia is a little over 4 feet.

Diastrophic dysplasia is a different form of short-limb dwarfism. It occurs in about 1 in 100,000 births, and is also sometimes associated with cleft palate, clubfeet, and ears with a cauliflower-like appearance. People who have this diagnosis tend to have shortened forearms and calves (this is known as mesomelic shortening).

Spondyloepiphyseal dysplasias (SED) refers to a group of various short-trunk skeletal conditions that occurs in about 1 in 95,000 babies. Along with achondroplasia and diastrophic dysplasia, it is one of the most common forms of dwarfism. In some forms, a lack of growth in the trunk area may not become apparent until the child is between 5 and 10 years old; other forms are apparent at birth. Kids with this disorder also might have clubfeet, cleft palate, and a barrel-chested appearance.

In general, dwarfism caused by skeletal dysplasias results in what is known as disproportionate short stature — meaning the limbs and the trunk are not the same proportionally as those of typically-statured people.

Metabolic or hormonal disorders typically cause proportionate dwarfism, meaning a person's arms, legs, and trunk are all shortened but remain in proportion to overall body size.

Diagnosis

Some types of dwarfism can be identified through prenatal testing if a doctor suspects a particular condition and tests for it.

But most cases are not identified until after the child is born. In those instances, the doctor makes a diagnosis based on the child's appearance, failure to grow, and X-rays of the bones. Depending on the type of dwarfism the child has, diagnosis often can be made almost immediately after birth.

Once a diagnosis is made, there is no "treatment" for most of the conditions that lead to short stature. Hormonal or metabolic problems may be treated with hormone injections or special diets to spark a child's growth, but skeletal dysplasias cannot be "cured."

People with these types of dwarfism can, however, get medical care for some of the health complications associated with their short stature.

Some forms of dwarfism also involve issues in other body systems — such as vision or hearing — and require careful monitoring.

Possible Complications and Treatments

Short stature is the one quality all people with dwarfism have in common. After that, each of the many conditions that cause dwarfism has its own set of characteristics and possible complications.

Fortunately, many of these complications are treatable, so that people of short stature can lead healthy, active lives.

For example, a small percentage of babies with achondroplasia may experience hydrocephalus (excess fluid around the brain). They may also have a greater risk of developing apnea — a temporary stop in breathing during sleep — because of abnormally small or misshapen anatomy or, more likely, because of airway obstruction by the adenoids or the tonsils. Occasionally, a part of the brain or spinal cord is compressed. With close monitoring by doctors, however, these potentially serious problems can be detected early and surgically corrected.

As a child with dwarfism grows, other issues may also become apparent, including:

  • delayed development of some motor skills, such as sitting up and walking
  • a greater susceptibility to ear infections and hearing loss
  • breathing problems caused by small chests
  • weight problems
  • curvature of the spine (scoliosis, kyphosis, and/or lordosis)
  • bowed legs
  • trouble with joint flexibility and early arthritis
  • lower back pain or leg numbness
  • crowding of teeth in the jaw

Proper medical care can alleviate many of these problems. For example, surgery often can bring relief from the pain of joints that wear out under the stress of bearing weight differently with limited flexibility.

Surgery also can be used to improve some of the leg, hip, and spine problems people with short stature sometimes face.

Nonsurgical options may help, too — for instance, excessive weight can worsen many orthopedic problems, so a nutritionist might help develop a healthy plan for shedding extra pounds. And doctors or physical therapists can recommend ways to increase physical activity without putting extra stress on the bones and joints.

Helping Your Child

Although types of dwarfism, and their severity and complications, vary from person to person, in general a child's life span is not affected by dwarfism. Although the Americans with Disabilities Act protects the rights of people with dwarfism, many members of the short-statured community don't feel that they have a disability.

You can help your child with dwarfism lead the best life possible by building his or her sense of independence and self-esteem right from the start.

Here are some tips to keep in mind:

  • Treat your child according to his or her age, not size. If you expect a 6-year-old to clean up his or her room, don't make an exception simply because your child is small.
  • Adapt to your child's limitations. Something as simple as a light switch extender can give a short-statured child a sense of independence around the house.
  • Present your child's condition — both to your child and to others — as a difference rather than a hindrance. Your attitude and expectations can have a significant influence on your child's self-esteem.
  • Learn to deal with people's reactions, whether it's simple curiosity or outright ignorance, without anger. Address questions or comments as directly as possible, then take a moment to point out something special about your child. If your child is with you, this approach shows that you notice all the other qualities that make him or her unique. It will also help prepare your child for dealing with these situations when you're not there.
  • If your child is teased at school, don't overlook it. Talk to teachers and administrators to make sure your child is getting the support he or she needs.
  • Encourage your child to find a hobby or activity to enjoy. If sports aren't going to be your child's forte, then maybe music, art, computers, writing, or photography will be.
  • Finally, get involved with support associations like the Little People of America. Getting to know other people with dwarfism — both as peers and mentors — can show your child just how much he or she can achieve.

Reviewed by: Angela L. Duker, MS, CGC
Date reviewed: March 2011