Fetal skeletal dysplasias are a complex group of developmental bone and cartilage disorders. There are over 175 different types of skeletal dysplasias.
Skeletal dysplasia occurs in approximately one in every 4,000 births. There are various modes of inheritance in the skeletal dysplasias. Some are sporadic (not inherited). Depending on the mode of inheritance, the chance of having another affected child is different. For example with an autosomal recessive inheritance, non-affected parents would have a 25% chance of having another affected child.
Fetal skeletal dysplasias usually result from mutated genes. However, some are sporadic (not inherited).
Skeletal dysplasia may be diagnosed by ultrasound (sonogram) examination prior to birth. However, the exact type of dysplasia can be difficult to diagnose until after birth. Generally, the type of dysplasia can be accurately diagnosed prenatally only 65% of the time. Evaluation of the bone structure is part of the routine ultrasound examination done by many obstetricians as part of their routine prenatal care around the 20th week of pregnancy. If skeletal dysplasia is suspected, the mother may undergo a more detailed or 3D ultrasound examination. This may be helpful in showing abnormal spatial relationships within the skeletal system, such as short ribs, absent bones or abnormal limb lengths. If it is detected on ultrasound, the patient may undergo a fetal MRI (magnetic resonance imaging) to aid in correctly diagnosing the type of dysplasia. Genetic testing may be useful to confirm the ultrasound findings.
Symptoms can include abnormal growth of the limbs, absence of a limb, duplication of fingers or toes and many other deformities.
After a baby is diagnosed with skeletal dysplasia, the Institute for Fetal Health will recommend further testing to pinpoint the type of dysplasia the baby has. The surgeons, geneticists, and genetic counselors spend time counseling parents about what to expect when their baby is born.
It is recommended that after the baby is born, parents bring their child to the monthly skeletal dysplasia program at Lurie Children's. This program allows families to see a geneticist, radiologist and orthopaedic surgeon all on the same day — making it easier for the child to receive thorough evaluation and management of their disease. In many instances, surgery and bracing of the bones can greatly improve the quality of life for these children.
The long-term outlook for a child born with skeletal dysplasia depends greatly on the type of dysplasia and the presence of other associated abnormalities. Approximately 25% of affected fetuses with a skeletal dysplasia are stillborn and about 30% die in the neonatal period (first six weeks of life). However, not all dysplasias have severe medical problems. For example many children born with achondroplasia, which is one of the most common types, can lead relatively normal lives. Additionally, there are many support groups online and in the community that can provide information, assistance and encouragement to families dealing with this problem. Little People of America is one such site.