What Is Skeletal Dysplasia?
Skeletal dysplasia is the medical term for what most people
refer to as “dwarfism”. The term is an umbrella for a group of hundreds of
conditions affecting bone and cartilage growth. A child born with skeletal dysplasia
will have abnormal differences in the size and shape of their legs, arms,
trunk, or skull. He or she may be very short in stature. Additionally, he or
she may also have arms and legs that are not in proportion with the rest of the
Skeletal dysplasia is a genetic condition. A change or defect
in a specific gene, called a mutation, causes the problems in growth. As a
whole, skeletal dysplasia is an uncommon condition. It
affects about one in every 4,000 births (Lurie).
What Causes Skeletal Dysplasia?
Skeletal dysplasia is
an inherited condition. It is caused by many different types of genetic
mutations. An inherited disorder implies that a child is born with the condition.
The genetic defect is passed down from parents to children through their genes.
These mutations prevent the bones from growing in a normal way. The disease
runs in families but can often appear without a family history of skeletal
The exact genetic
defect a person with the condition has is sometimes difficult to determine. The
most common type of skeletal dysplasia is called achondroplasia. This is caused by mutations in the FGFR3 gene. Most
of the time, the parents of a child born with achondroplasia are of normal
height and stature (Unger, 2002).
Other common types of skeletal dysplasia include:
dysplasia: results in extra folds of skin on the arms and legs, as well as
extremely short limbs
affects conversion of cartilage into bone, resulting in short arms and legs, as
well as short, broad hands and feet
dysplasia: often fatal in the newborn period, this disorder causes dangerous
bowing of the long bones in the legs and often the arms as well
imperfecta: a disorder that results in fragile bones that break easily
a type of disorder that affects the development of bones and cartilage, resulting
in skeletal abnormalities including short limbs and a small body (CHOP)
What Are the Symptoms of Skeletal Dysplasia?
Specific symptoms of skeletal dysplasia vary with each type.
In general, people with the condition have arms, legs, trunk, and a skull of
unusual shape and size. Other symptoms include:
- shortened stature
- fractured bones
- a large head
- absence of a limb
- duplication of fingers or toes
- club feet
- stubby fingers
- missing ribs
- joint pain
- developmental delays
- mental retardation
How Is Skeletal Dysplasia Diagnosed?
Sometimes a child with skeletal dysplasia will be born with a
short stature. In other cases, the child will be born with a normal birth
length and fail to grow later on. A child’s parent or pediatrician may first
discover the dysplasia when they notice that the child’s head is growing out of
proportion to the rest of the body.
A doctor may first conduct a physical examination. He or she will
measure the child’s height, weight, and head circumference. The lower and upper
segments of the body are measured separately to determine proportion. The
doctor will also ask for a thorough family and patient history.
Types of skeletal dysplasia are generally
classified by which parts of the skeleton are involved (Unger,
2002). X-rays and imaging techniques, such as magnetic resonance
imaging (MRI) or computed tomography (CT) may be used by a doctor to identify
and assess deformities in bones more accurately. Genetic analysis and molecular
analysis may be performed to identify the type of skeletal dysplasia. They can
also identify the exact gene mutation causing the condition.
It is sometimes possible to diagnose skeletal dysplasia prior to
birth with an ultrasound examination. An ultrasound is a routine exam done by a
doctor during a woman’s pregnancy. A doctor may notice abnormal bone structure
or limb lengths during the examination. A more detailed ultrasound may be
conducted to help diagnose the dysplasia. The exact type of dysplasia is often
difficult to diagnose until after birth occurs.
How Is Skeletal Dysplasia Treated?
Often a team of doctors from many specialties reviews each
individual case of skeletal dysplasia before deciding on a treatment plan. This
may involve neurosurgeons, orthopedists, ophthalmologists, endocrinologists, radiologists,
geneticists, neurologists, and other doctors. If the bones are constricting the
spinal cord or brain stem, for example, a pediatric neurosurgeon may remove the
bone or bones causing the problem. The spine will then be supported with metal
Some children may be given growth hormones to help boost
growth. This type of treatment involves injections with needles every day. The
hormone treatment can help increase height, but many children will probably
still remain below normal adult height even with treatment. Surgery to lengthen
the limbs may also be used to induce bone growth. However, there are many
complications in this type of surgery. It may involve multiple procedures and
usually has a long recovery period.
What Can Be Expected in the Long-Term?
The long-term outlook for children born with skeletal
dysplasia greatly depends on the type of dysplasia. According to the Ann &
Robert H. Lurie Children’s Hospital of Chicago, about a quarter of fetuses with
a skeletal dysplasia will not be born alive (stillborn). About 30 percent will
die in the first six weeks after birth. However, many children will live normal
lives with normal intelligence and life expectancy (Lurie).