Ellis-van Creveld syndrome
Ellis–van Creveld syndrome is sometimes also called chondroectodermal dysplasia, mesoectodermal dysplasia, or simply EVS for short. EVS is a growth disorder that is inherited. It is a more severe form of Weyers acrofacial dysostosis, but the two conditions share the same basic set of symptoms. Ellis–van Creveld syndrome is considered a rare condition in the general population. It is classified alongside similar conditions as a type of short rib-polydactyly syndrome.
Definition & Facts
Ellis–van Creveld syndrome is named after two doctors, Richard W.B. Ellis and Simon van Creveld. Both practicing pediatricians, the two first identified Ellis–van Creveld syndrome in 1940. However, they did not name it after themselves. Rather, they decided to call the syndrome "chondroectodermal dysplasia."
Ellis–van Creveld syndrome is rare in the general population, affecting only one case in every 30,000 to 200,000 infants. However, there is one place where the syndrome is seen far more frequently: in the Amish community called "Old Order Amish" that currently lives in Pennsylvania.
Researchers call this unusual incidence evidence of the genetic drift theory. Genetic drift occurs when a population's gene pool becomes quite small and constrained for any number of reasons, such as a community where members are only permitted to pick a partner from within the same community.
An extreme form of this is called founder effect, which occurs when a small gene pool produces a large amount of certain recessive genes. It is now known that the founder effect is at the root of why there are so many cases of Ellis–van Creveld syndrome within the Old Order Amish community; all cases within the community have even been traced back to a single Amish couple.
Symptoms & Complaints
- Short forearms.
- Short lower legs.
- Short ribs.
- Narrow ribs.
- Polydactyly (more than five per hand or foot) toes and fingers.
- Fingernails and toenails that are malformed.
- Dental deformities.
- Hair abnormalities, including hair that is very fine, sparse or missing.
- Heart defects (present in an estimated 50 percent of cases).
- Undescended testicles in male patients (cryptorchidism).
- Abnormally placed urine canal in the penis (epispadias).
- Abnormalities of the chest wall, respiratory system, and vertebra
- Presence of natal teeth (neonatal teeth) at birth and delay in growth of normal teeth.
- Widely spaced or "peg" (abnormally shaped) teeth.
- Cleft lip and cleft palate.
There are two different genes, EVC and EVC2, that can mutate to cause Ellis–van Creveld syndrome. These two genetic mutations are the culprits in about 50 percent of cases of the syndrome. However, the cause for the other 50 percent of cases still remains unknown.
To date, researchers know little about EVC and EVC2. However, both genes are suspected to regulate cell-to-cell communication during physical development. By interfering with normal communication, it is thought that the mutations in EVC and EVC2 can prevent normal fetal development during pregnancy.
Ultimately, heritable cases of Ellis–van Creveld syndrome are caused by an autosomal recessive condition, which means that both parents must contribute one or both genes linked to the syndrome in order to pass it along to their offspring. If only one parent passes along the gene, the child will be a genetic carrier.
Diagnosis & Tests
Diagnosis of Ellis–van Creveld syndrome can involve a number of different tests. Genetic testing may be done at any time to look for mutations in the EVC and EVC2 genes. Prenatal ultrasound tests can often detect the syndrome in the unborn infant. Once the infant is born, observation of symptoms as part of a physical examination or newborn screening is the chief method for diagnosing Ellis–van Creveld syndrome.
Often the first symptom to appear is polydactyly fingers and/or toes, which will be visible immediately. Natal teeth will also be visible at birth. Congenital heart defects will be detectable by a stethoscope test. Male patients may present with undescended testicles or an abnormal urine canal at birth. As the individual grows, growth delays and bone abnormalities will start to appear.
Treatment & Therapy
Treatment for Ellis–van Creveld syndrome can begin as soon as symptoms begin to arise. For infants that are born with respiratory or heart abnormalities, surgery may be immediately indicated. Natal teeth may be removed because they can get in the way of normal feedings. In some cases, while a treatment plan will likely be outlined immediately, some treatments will have to wait until the child gets a little older.
Typically, due to the array of abnormalities and complications that are associated with Ellis–van Creveld syndrome, the treatment team will include a variety of specialists including a pediatrician, pulmonologist, urologist, orthopedist, dentist/orthodontist, cardiologist, physical therapist, podiatrist and others as symptoms may indicate.
Unfortunately, there is no treatment for the syndrome itself, which means that treatment will always focus on controlling and easing symptoms.
Prevention & Prophylaxis