Phocomelia, or amelia, is a rare condition that causes very short limbs. It’s a type of congenital disorder. This means it’s present at birth.
Phocomelia can vary in type and severity. The condition might affect one limb, the upper or lower limbs, or all four limbs. It most commonly affects the upper limbs.
The limbs can also be reduced or missing completely. Sometimes, the fingers may be missing or fused together.
If all four limbs are absent, it’s called tetraphocomelia. “Tetra” means four, “phoco” means seal, and “melos” means limb. This term refers to the ways the hands and feet look. The hands may be attached to the shoulders, while the feet may be attached to the pelvis.
Phocomelia is often related to issues during early pregnancy. Specifically, within the first 24 to 36 days of life, the fetus begins to develop limbs. If this process is disrupted, the cells can’t divide and grow normally. This prevents proper growth of the limbs, resulting in phocomelia.
In this article, we’ll explore the possible causes of limb malformations, along with potential treatment options.
The underlying causes of phocomelia are somewhat unclear. There are likely multiple factors involved.
Inherited as part of a genetic syndrome
Phocomelia can be genetically passed down within families. It’s associated with an abnormality in chromosome 8. Phocomelia is an autosomal recessive trait. It means both parents need to have the abnormal gene in order for a child to have it.
In some cases, a spontaneous genetic defect may cause phocomelia. This means the mutation is new and isn’t related to an inherited abnormality.
Another cause of phocomelia is maternal intake of thalidomide during the first trimester of pregnancy.
Thalidomide is a sedative that was released in 1957. For about 5 years, the drug was used for a variety of conditions, including morning sickness and nausea in pregnancy. It was thought to be very safe and wasn’t linked to any side effects.
Eventually, thalidomide use during early pregnancy was found to cause birth defects. A variety of abnormalities were reported, but the most common was phocomelia.
Because of these side effects, thalidomide was withdrawn as a pregnancy drug in 1961. But babies with thalidomide-related conditions were born until 1962. It’s caused birth defects in more than 10,000 babies around the world.
Today, the drug is used for conditions like Crohn’s disease, multiple myeloma, and leprosy. If you receive a prescription for thalidomide, it’s important to make sure you’re not pregnant.
Having these factors during pregnancy might also contribute to phocomelia:
The primary symptom of phocomelia is shortened or missing limbs. It may also cause issues with:
If thalidomide is the cause of phocomelia, it will likely be accompanied with more serious issues. That’s because thalidomide can affect almost every tissue and organ.
Together, these issues are known as thalidomide syndrome or thalidomide embryopathy. In addition to phocomelia, it might include:
- syndactyly (webbed fingers or toes)
- polydactyly (extra fingers or toes)
- heart problems
- kidney and urinary tract issues
- bowel abnormalities
- external and internal genital issues
- nervous system irregularities
- underdeveloped shoulder and hip joints
In particular, undersized shoulder and hip joints are unique to thalidomide syndrome. Limb malformations in thalidomide embryopathy are also usually symmetrical.
There isn’t a current cure for phocomelia. However, the following forms of treatment can help manage symptoms:
Prosthetics are artificial limbs that are attached to the body. They can add length to an existing limb or replace an absent one. This makes it easier to do everyday activities, which can improve overall quality of life.
Treatment may also include various forms of rehabilitation, such as:
- Occupational therapy. With occupational therapy, a person with phocomelia can learn how to do daily tasks with ease.
- Physical therapy. This type of therapy can improve movement, strength, and posture.
- Speech therapy. Speech therapy can help manage speech problems.
Phocomelia treatment rarely involves surgery. Generally, it’s only done if phocomelia is due to a genetic mutation.
There isn’t one specific procedure used. If surgery is recommended, it may involve:
- correcting structural issues in the face
- stabilizing joints
- lengthening existing bones
- improving thumb opposition (ability to rotate the thumb)
The best option depends on the limbs affected by phocomelia.
Phocomelia is an extremely rare condition. It’s characterized by one or more shortened limbs.
In more serious cases, the limbs might be completely absent. Other possible symptoms include issues with the eyes, growth, and cognition.
Both inherited and spontaneous genetic mutations can cause phocomelia. Certain substances used during the first stages of pregnancy can also cause it, such as thalidomide or cocaine.