Skeletal Dysplasia

What are skeletal dysplasias?

Skeletal dysplasias are genetic disorders that prevent the fetal bones and cartilage from growing and developing properly.

There are more than 450 types of skeletal dysplasia. These rare conditions cause a wide range of deformities, from mild to severe, including short stature or dwarfism.

How does skeletal dysplasia affect my baby?

Skeletal dysplasia can cause abnormalities of the bones in the body, such as the size and shape of the skull, legs, arms and trunk. Approximately 5% of children with congenital birth defects have skeletal dysplasias.

While the symptoms vary based on each baby’s specific disorder, complications include:

• Short stature
• Arms and legs that are too short compared to the rest of the body
• A large head and prominent forehead
• Curved bones, including the spine (scoliosis) and legs (bowlegs or knock-knees)
• Soft, brittle or fractured bones
• Joint pain and stiffness
• Small thorax (chest), preventing proper lung development
• Respiratory, neurologic and cardiac complications
• Hydrocephalus
• Deformities of the hands and feet, including duplication of fingers or toes
• Hearing loss
• Cleft palate
• Developmental delays

Types of Skeletal Dysplasia

The most common non-lethal dysplasias include:

• Achondroplasia, the most common type of dwarfism, with shortened limbs
• Campomelic dysplasia, a condition for newborns that causes bowing of the long bones in the baby’s legs and arms

The three most common lethal dysplasias are:

• Achondrogenesis, causing a small thorax (chest), underdeveloped lungs, and short limbs
• Osteogenesis imperfecta II, also known as brittle-bone disease due to decreased bone density that results in fragile, easily broken bones
• Thanatophoric dysplasia, characterized by extremely short limbs and extra folds of skin on the arms and legs, a small ribcage and underdeveloped lungs

Cause and Prevalence

Skeletal dysplasias are estimated to affect 1 in every 4,500 births.

These disorders are genetic, meaning they are caused by a defective gene that prevents the baby’s skeleton from developing normally. The condition may be inherited or it can appear in a fetus where there is no family history (known as a spontaneous gene mutation). While we know the genetic cause for most of the skeletal dysplasias, in some cases we may not be able to find the specific genetic change.

Prognosis

The outlook for each baby depends on the type of skeletal disorder and any associated abnormalities. In severe cases, these disorders can result in stillbirth or the newborn isn’t able to survive long-term.

Diagnosis

Skeletal dysplasia may be diagnosed during pregnancy following a routine ultrasound. The ultrasound may show that some or all of the fetal bones are smaller than expected for gestational age.

If a skeletal dysplasia is suspected or diagnosed, you may be referred to a fetal center for a comprehensive evaluation and specialized care. At Texas Children’s Fetal Center, we arrange for you to visit as quickly as possible for a detailed assessment by a team of specialists experienced in the diagnosis and treatment of these rare disorders, including maternal-fetal medicine (MFM) physicians, fetal imaging experts, genetic counselors, geneticists, and neonatologists.

Additional testing to determine the severity of the condition and underlying cause may include:

• Advanced ultrasound imaging to assess bone development
• Ultra-fast MRI or low-dose CT for a more detailed view of fetal anatomy and skeletal abnormalities
• Amniocentesis to test for known genetic causes of skeletal dysplasias

In some cases, the diagnosis might be made from X-rays and clinical features but the exact type of disorder may be difficult to diagnose until after birth. In other cases, we are not able to make a diagnosis prenatally, despite detailed imaging studies and genetic testing.

Following this thorough evaluation, our specialists will meet with you about your results, answer any questions you have, and discuss your baby’s prognosis and treatment needs at birth. An accurate diagnosis during pregnancy enables your family and your healthcare team to plan ahead for the special needs of your baby and arrange for the earliest possible treatment.

Treatment During Pregnancy

If skeletal dysplasia is diagnosed during pregnancy, you and your baby will be closely monitored with regular ultrasounds to watch for signs of complications.

There are no fetal treatments available for these disorders.

During pregnancy you and your family may meet with genetic counselors regarding the risks of recurrence in future pregnancies and pediatric specialists to prepare for the treatment needs of your newborn.

Delivery

For the best possible outcome, delivery should take place at a hospital with the specialized care and resources required by babies with skeletal dysplasia, including the highest level neonatal intensive care unit (NICU) for premature or critically ill newborns.

Delivery should be carefully planned and coordinated with a team of specialists experienced in managing these complex pregnancies. Our Fetal Center team works closely with pediatric experts from Texas Children’s Hospital, including geneticists, neonatologists, and orthopedists experienced in the treatment of skeletal dysplasia, ensuring the best possible care for your baby every step of the way.

Texas Children’s is consistently ranked one of the best children’s hospitals in the nation by U.S. News & World Report.

Treatment after Birth

Treatment needs after birth depend on the specific type of skeletal dysplasia and the baby’s condition.

Treatment strategies may include:

• IV medications or injections for specific conditions (such as osteogenesis imperfecta and hypophosphatasia)
• Physical therapy
• Surgery to correct physical abnormalities such as a cleft palate or clubfoot or to address complications, such as relieving pressure on the spinal cord
• Brain shunt to drain excess fluid in the brain (hydrocephalus)

Postnatal Care Team

A unique and distinct advantage for mothers delivering at Texas Children’s Pavilion for Women is our location inside one of the largest and most renowned children’s hospitals in the world, for seamless access to the critical care services and specialists your child may need after birth.

For newborns with skeletal dysplasia, this means no transfers during critical postnatal periods. It also means the pediatric specialists responsible for treating your child have been an integral part of their care team since before birth.

Texas Children's Skeletal Dysplasia Program provides diagnosis, treatment and follow-up care for babies with skeletal dysplasia from birth through adulthood. Most children with skeletal dysplasias are under the care of medical geneticists and pediatric orthopedic surgeons. Other specialists may be involved, depending upon the diagnosis and child’s needs.

For more information about Texas Children's Skeletal Dysplasia Program, call 832-822-4298.

Why Texas Children’s Fetal Center?

• A single location for expert maternal, fetal and pediatric care. At Texas Children’s Hospital, you and your baby receive the specialized care required for the diagnosis and treatment of skeletal dysplasia all in one location, for highly coordinated care and treatment planning, including immediate access to our level IV NICU.
• A skilled, experienced team with proven outcomes. We have a dedicated team of maternal-fetal medicine specialists, fetal imaging experts, neonatologists, and others who work in concert to care for you and your baby, using proven protocols we’ve developed over the years. With their combined expertise and unified approach, this team offers the best possible care for these rare fetal conditions.
• We care for your child’s needs at every stage of life. Our comprehensive approach starts with your first prenatal visit and continues through delivery, postnatal care, and throughout childhood and adolescence, thanks to one of the nation’s leading teams of fetal and pediatric specialists.