Amelia is a term that describes a birth defect where the individual is missing one or more limbs (arms, legs, hands, feet). There are a variety of reasons why amelia may occur. amelia is considered to be a very rare type of birth defect. It may be present on its own or in connection with other developmental issues.
Definition & Facts
The National Institutes of Health (NIH) reports that amelia is so rare that it only happens about 0.55 in every 1,000 births. When amelia occurs, the limb is completely absent or missing. Because so few cases are reported, researchers have few opportunities to study what causes amelia and how to potentially prevent it.
The word amelia literally translates to mean "congenital amputation." When only a stump is present where the full limb would be, this is called an "amelia."
Symptoms & Complaints
- Abnormal vaginal bleeding during pregnancy.
- Toxemia or pre-eclampsia (metabolic abnormalities that can include high blood pressure, swelling, and high protein content in the urine).
- Diabetes mellitus in any of its forms.
Symptoms of possible amelia that the fetus may exhibit while in utero include the following:
- Increased levels of alpha fetoprotein in the fetus's liver.
- Only one artery present in the umbilical cord.
- Extremely low projected birth weight even without the missing limb(s).
- Very low placental weight.
- Baby is abnormally positioned in the womb (breech birth, legs first, etc.)
There are several known possible reasons why amelia may affect an unborn child. The eight most common reasons why amelia can happen include the following:
- Hereditary. In the case of congenital amelia, the absence of the limb is caused by a genetic mutation that gets passed from one or both parents to the infant.
- Sporadic. In the case of sporadic amelia, the limb goes missing as a result of a random (non-heritable) gene mutation that happens during the infant's own development. When sporadic amelia occurs, the mutation has most likely happened between week 24 and week 36 of the woman's pregnancy.
- Tetra-amelia syndrome. Tetra-amelia syndrome is a particularly rare syndrome that causes infants to be born missing all four limbs. In most cases, the overall genetic malformations are so severe that the infant passes away in utero or at birth.
- Exposure to toxins (teratogenic substances). If the mother is exposed to certain toxins, such as thalidomide or alcohol, amelia may result in the fetus.
- Maternal diabetes. If the mother has gestational diabetes, this can cause amelia.
- Vascular constriction. If for any reason there is a constriction that develops inside the womb, this can cause a limb to fail to form.
- Deformities in major organs. In many cases (an estimated 50 percent of the time), amelia occurs when there is already malformation or deformity in one or more major organs.
- Unknown causes (Idiopathy. At times, idiopathic amelia happens and no causes can be specifically identified.
Diagnosis & Tests
Diagnosis of amelia often will not occur until the day of delivery. This is because in many cases, amelia may not be suspected, so special prenatal testing will not look for the condition.
However, if a parental medical history discloses that there has been exposure to the class of toxins known as teratogens (toxins that can cause harm to a fetus), then prenatal diagnostic procedures may be recommended.
Typically, testing will use ultrasonography to look at the fetus's developing body. The ultrasound will attempt to identify whether limbs are missing or there are other congenital defects in organs or body systems. In particular, the ultrasound will look for any areas of potential constriction inside the womb that could cause a limb to fail to grow.
Treatment & Therapy
If in utero constriction is detected during an ultrasound, it is often possible to treat it by performing prenatal surgery. This can avert a case of amelia.
However, in many cases amelia is related to deformities or absence of other organs or body systems. In these cases, it may not be possible to treat these in utero. In cases of amelia that are not identified until birth, treatment will attempt to address symptoms.
The goal of treatment will be to help the child navigate in as normal a manner as possible to have as high a quality of life as possible. Treatment may include physical therapy, use of assistive devices or prosthetics, occupational therapy to find alternate ways to accomplish daily life tasks, and support for the whole family as the child grows up.
The treatment team typically includes a diverse group of professionals, including occupational and physical therapists, a prosthetist, a pediatrician, an orthopedist and other professionals as the infant's condition may indicate.
Prevention & Prophylaxis
Another appropriate method for potential prevention of amelia is for the mother to steer clear of smoking, drinking, using any drugs (including certain prescription drugs) and exposure to any toxins during the time period when she is trying to conceive and throughout her pregnancy. This will minimize the potential risk of any birth defects, including amelia.