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."
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.
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 and Skull:
- long and narrow skull
- prominent forehead
- flat face with a depressed nasal bridge
- possible cleft palate
Trunk, Chest and 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 and Legs:
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).
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.
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 should be treated along standard lines with corrective casting and surgery, depending upon the severity of the problem.
The most significant abnormality in campomelic dysplasia is the lack of development of the cartilage rings supporting the tracheobronchial 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.
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.
Some phenotypic females may genetically be males.
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.
- Jones, Kenneth L. Recognizable Patterns of Human Malformation. Philadelphia, PA: Elsevier Saunders. 2006.
- Norman, EK. Pedersen, JC. Stiris, G. Van der Hagen, CB. 1993. Campomelic dysplasia-an underdiagnosed condition? European Journal of Pediatrics. 152: 331-333.
- Scott, Charles I. Dwarfism. Clinical Symposium, 1988; 40(1):21-24.
- Spranger, Jurgen W. Brill, Paula W. Poznanski, Andrew. Bone Dysplasias: An Atlas of Genetic Disorder of Skeletal Development. Oxford: Oxford University Press. 2002.
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Genetic tests are done by analyzing small samples of blood or body tissues. They determine whether you, your partner, or your baby carry genes for certain inherited disorders.
Genetic testing has developed enough so that doctors can often pinpoint missing or defective genes. The type of genetic test needed to make a specific diagnosis depends on the particular illness that a doctor suspects.
Many different types of body fluids and tissues can be used in genetic testing. For deoxyribonucleic acid (DNA) screening, only a very tiny bit of blood, skin, bone, or other tissue is needed.
Genetic Testing During Pregnancy
For genetic testing before birth, pregnant women may decide to undergo amniocentesis or chorionic villus sampling. There is also a blood test available to women to screen for some disorders. If this screening test finds a possible problem, amniocentesis or chorionic villus sampling may be recommended.
Amniocentesis is a test usually performed between weeks 15 and 20 of a woman's pregnancy. The doctor inserts a hollow needle into the woman's abdomen to remove a small amount of amniotic fluid from around the developing fetus. This fluid can be tested to check for genetic problems and to determine the sex of the child. When there's risk of premature birth, amniocentesis may be done to see how far the baby's lungs have matured. Amniocentesis carries a slight risk of inducing a miscarriage.
Chorionic villus sampling (CVS) is usually performed between the 10th and 12th weeks of pregnancy. The doctor removes a small piece of the placenta to check for genetic problems in the fetus. Because chorionic villus sampling is an invasive test, there's a small risk that it can induce a miscarriage.
Why Doctors Recommend Genetic Testing
A doctor may recommend genetic counseling or testing for any of the following reasons:
- A couple plans to start a family and one of them or a close relative has an inherited illness. Some people are carriers of genes for genetic illnesses, even though they don't show, or manifest, the illness themselves. This happens because some genetic illnesses are recessive — meaning that they're only expressed if a person inherits two copies of the problem gene, one from each parent. Offspring who inherit one problem gene from one parent but a normal gene from the other parent won't have symptoms of a recessive illness but will have a 50% chance of passing the problem gene on to their children.
- A parent already has one child with a severe birth defect. Not all children who have birth defects have genetic problems. Sometimes, birth defects are caused by exposure to a toxin (poison), infection, or physical trauma before birth. Often, the cause of a birth defect isn't known. Even if a child does have a genetic problem, there's always a chance that it wasn't inherited and that it happened because of some spontaneous error in the child's cells, not the parents' cells.
- A woman has had two or more miscarriages. Severe chromosome problems in the fetus can sometimes lead to a spontaneous miscarriage. Several miscarriages may point to a genetic problem.
- A woman has delivered a stillborn child with physical signs of a genetic illness. Many serious genetic illnesses cause specific physical abnormalities that give an affected child a very distinctive appearance.
- The pregnant woman is over age 34. Chances of having a child with a chromosomal problem (such as trisomy) increase when a pregnant woman is older. Older fathers are at risk to have children with new dominant genetic mutations (those caused by a single genetic defect that hasn't run in the family before).
- A standard prenatal screening test had an abnormal result. If a screening test indicates a possible genetic problem, genetic testing may be recommended.
- A child has medical problems that might be genetic. When a child has medical problems involving more than one body system, genetic testing may be recommended to identify the cause and make a diagnosis.
- A child has medical problems that are recognized as a specific genetic syndrome. Genetic testing is performed to confirm the diagnosis. In some cases, it also might aid in identifying the specific type or severity of a genetic illness, which can help identify the most appropriate treatment.
A Word of Caution
Although advances in genetic testing have improved doctors' ability to diagnose and treat certain illnesses, there are still some limits. Genetic tests can identify a particular problem gene, but can't always predict how severely that gene will affect the person who carries it. In cystic fibrosis, for example, finding a problem gene on chromosome number 7 can't necessarily predict whether a child will have serious lung problems or milder respiratory symptoms.
Also, simply having problem genes is only half the story because many illnesses develop from a mix of high-risk genes and environmental factors. Knowing that you carry high-risk genes may actually be an advantage if it gives you the chance to modify your lifestyle to avoid becoming sick.
As research continues, genes are being identified that put people at risk for illnesses like cancer, heart disease, psychiatric disorders, and many other medical problems. The hope is that someday it will be possible to develop specific types of gene therapy to totally prevent some diseases and illnesses.
Gene therapy is already being studied as a possible way to treat conditions like cystic fibrosis, cancer, and ADA deficiency (an immune deficiency), sickle cell disease, hemophilia, and thalassemia. However, severe complications have occurred in some patients receiving gene therapy, so current research with gene therapy is very carefully controlled.
Although genetic treatments for some conditions may be a long way off, there is still great hope that many more genetic cures will be found. The Human Genome Project, which was completed in 2003, identified and mapped out all of the genes (about 25,000) carried in our human chromosomes. The map is just the start, but it's a very hopeful beginning.
Reviewed by: Larissa Hirsch, MD
Date reviewed: September 26, 2016