Diastrophic dysplasia, also known as diastrophic dwarfism, is a rare genetic condition that affects cartilage and bones.
Diastrophic dysplasia (DTD) is a type of skeletal dysplasia, a group of conditions often resulting in dwarfism. DTD may cause a person to have short stature and very short arms and legs.
DTD is congenital, which means it’s present at birth. It’s extremely rare, but people with Finnish ancestry on both sides may have a
In this article, we explore DTD, including its causes, characteristics, diagnosis and treatment, possible complications, and outlook.
The cause of DTD is a mutation in a gene known as SLC26A2 or DTDST, which stands for “diastrophic dysplasia sulfate transporter.”
In people without the mutation, this gene provides instructions for how to properly develop cartilage in embryos and babies and how to later convert it into bones. A mutation in the gene renders these instructions ineffective, resulting in impaired cartilage and bone development.
DTD is an autosomal recessive genetic disorder. This means that two copies of the mutated DTDST gene (one from each parent) are necessary for the condition to develop. People who have only one affected copy don’t develop DTD, but they are considered DTD carriers. This means they can pass the condition down to their children.
If both parents are carriers, their children have a 25% chance of being born with DTD.
DTD can have very different signs and symptoms, even among the members of one family. However, most of them are related to unusual bone and joint features, such as:
- very short limbs
- unusual curvature of the spine
- hand and foot differences, including unusually short fingers or toes (brachydactyly)
- hip dysplasia, in which hip joints are misaligned or crooked
- an unusually high, prominent forehead
- clubfoot (an inward or upward turning of the feet)
- irregularities in the ear cartilage
- cleft palate (an opening or gap in the roof of the mouth)
- hitchhiker’s thumb (unusually flexible thumbs)
DTD can have many complications. Some can be life threatening, especially in newborn babies.
The condition’s effects on cartilage and bone development can cause unusual curving of the spine, which can worsen with age. This may include:
- scoliosis, a sideways spine curvature
- kyphosis, an excessive upper back curvature, particularly in the neck area
- lordosis, an excessive lower back curvature
These spinal conditions can cause further issues, such as severe back pain.
DTD often causes joint irregularities called contractures, which can restrict movement. The affected joints may also be painful (osteoarthritis).
Joint issues often make walking difficult and tend to worsen with age. Some people with DTD walk on their tiptoes.
Many children with DTD also experience joint dislocations. These often result from bearing weight when walking or standing and usually occur in the hips and knees.
Most newborns with DTD have fluid-filled sacs (cysts) in the outer cartilage of their ears. The cysts may first become swollen and inflamed and later develop into bone growths. This can result in hearing difficulties.
Breathing difficulties can result from airway narrowing caused by irregularities in the cartilaginous tissue. These issues can affect the:
Severe kyphosis may also restrict breathing. Breathing difficulties can be life threatening.
DTD can cause other health concerns as well. For example, about one-third of babies and kids with DTD experience issues with their teeth.
If your family has a history of DTD and you are planning to have children, your doctor will likely order DNA tests before and during pregnancy to confirm or rule out the presence of the mutation. Healthcare professionals may also notice the features of this condition during the second-trimester ultrasound.
The final diagnosis usually happens at birth, after a clinical evaluation involving a physical exam and a variety of tests. This evaluation may include imaging studies such as:
There is no cure for DTD. The goals of treatment are to reduce symptoms and prevent complications.
Treatment for DTD usually involves a team of healthcare professionals, including:
Newborns with DTD have an increased risk of death due to breathing difficulties. However, people who survive the newborn stage usually have a typical life expectancy.
Many complications of DTD can significantly decrease quality of life. People with DTD and their caregivers may experience challenges such as:
- a lack of available information
- financial concerns
- difficult feelings and emotions
- adjustments to daily activities and roles
- social stigma and isolation
Your doctor may have some resources to help you cope with the effects of this condition. You can visit the National Institutes of Health’s website to find a list of organizations that may be helpful.
Let’s go over a few questions that parents of babies with DTD commonly ask.
Is diastrophic dysplasia fatal?
DTD is not fatal, but newborns have a risk of death due to potential breathing complications.
Can you prevent diastrophic dysplasia?
There is no way to prevent this condition if your baby has the related gene mutation. If this condition runs in your family, make sure to let your doctor know. They will likely perform DNA testing in both you and your partner to determine the chances that your future children will have DTD.
Does diastrophic dysplasia cause cognitive impairments?
DTD does not affect cognitive (thinking) abilities. Children and adults with this condition have typical intelligence levels.
DTD is a rare genetic condition that causes short stature and unusually short limbs. People with DTD can experience many health complications related to their joints and bones.
The condition is typically diagnosed at birth, but a DNA test can help you find out whether your children may have DTD.
There’s no cure, but doctors can help you manage the symptoms and prevent complications. Support groups are also available to help people with DTD and their caregivers navigate this condition.