What Is Achondroenesis?
Achondrogenesis is a rare and severe
group of genetic disorders that results in a short trunk, small limbs, and a
narrow chest. It occurs when a person’s body does not produce enough growth
hormone. As a result, cartilage and bone don’t develop properly, causing
abnormalities in the skeletal system.
You’re more likely to have a child
with this disorder if both you and your partner carry the gene. Most babies
with achondrogenesis die before or right after birth because they can’t breathe
properly. No treatments exist for the disorder. Care focuses on making the baby
as comfortable as possible for the duration of their life.
Types of Achondrogenesis
This disorder is usually categorized
into three different types based on the pattern of inheritance, signs, and
In achondrogenesis type 1A, the baby’s
skull bone is very soft and the limbs are very short. As with all three types,
the chest is narrow, making it hard for the baby to breathe. The bones in the
spine and pelvis don’t form well. The baby also has short ribs that break
Type 1B is very similar to 1A, and
distinguishing between the two types often requires a genetic test. In addition
to the very short limbs and narrow chest, type 1B includes a round belly and
sometimes a pouch near the groin or belly button. If your baby has this type of
achondrogenesis, their feet may be inwardly rotated. The toes and fingers are
also very short.
As with the other two types, babies
born with type 2 achondrogenesis have short limbs and a narrow chest. Their
ribs are usually short and their lungs aren’t well developed. The bones in the
spine and pelvis are not well formed. The roof of the mouth may have an opening
known as a cleft palate.
A small chin and large forehead are other signs. The belly may be large, and
some infants will have too much fluid in their bodies before they’re born.
According to statistics collected by
the National Institute of Health, the occurrence of type 2 achondrogenesis and
a similar bone growth disorder called hypochondrogenesis have been observed in
one in every 40,000 to 60,000
What Causes Achondrogenesis?
This rare disorder is hereditary. If
both you and your partner carry the gene, there is a 25-percent chance that
your child will have the condition. Since the genetic disorder is recessive,
the parental carriers of the gene show no signs of the condition.
What Are the Symptoms of Achondrogenesis?
Short limbs and a narrow chest are
common to all types of achondrogenesis. The other symptoms vary by type.
Genetic testing may be necessary to distinguish the exact type.
Type 1A Symptoms
- soft skull bone
- poorly formed spine and pelvic bones
- short and easily breakable ribs
Type 1B Symptoms
- round belly
- pouch near the belly button
- short toes and fingers
- inwardly rotated feet
Type 2 Symptoms
- short ribs
- poorly developed lungs
- cleft palate
- small chin
- large forehead and belly
How Is Achondrogenesis Diagnosed?
Your doctor will order X-rays to
examine your baby’s bones. Usually, the signs are obvious to the human eye, and
your doctor will know right away if your baby has some type of the condition.
No treatments exist for
achondrogenesis. To keep your baby as comfortable as possible, the hospital
will monitor the infant and possibly use a breathing machine. Medication may
also be needed to limit pain and discomfort.
What Can Be Expected in the Long Run?
Babies born with achondrogenesis
usually die quickly because their small chests don’t allow them to breathe.
Many die in utero.
Preventing Achondrogenesis: Genetic
If achondrogenesis exists in your
family, your only option for preventing the disorder is to have genetic
counseling prior to starting a family. During genetic counseling, a specialist
will collect your medical histories, asking about illnesses that have occurred
on both sides of your families. Medical practitioners will run tests to
determine whether you and your partner are carrying the genes for
achondrogenesis. Couples with a family history of achondrogenesis might choose
to exercise this option before deciding whether or not to have a baby.