Spondylometaphyseal dysplasia, A4 type (SMD A4) is a rare genetic disorder that affects the bones and cartilage. It is characterized by short stature, a short neck, and a flattened face. Other features may include a short trunk, a curved spine, and a flattened chest. Affected individuals may also have skeletal abnormalities such as short ribs, a narrow chest, and a short, broad pelvis. In some cases, SMD A4 can cause joint problems, such as hip and knee pain.

The symptoms of Spondylometaphyseal dysplasia, A4 type, can vary from person to person, but may include:

- Short stature
- Abnormal curvature of the spine (scoliosis)
- Abnormal shape of the vertebrae
- Abnormal shape of the pelvis
- Abnormal shape of the ribs
- Abnormal shape of the shoulder blades
- Abnormal shape of the long bones
- Abnormal shape of the skull
- Abnormal shape of the facial bones
- Abnormal shape of the jaw
- Abnormal shape of the hands and feet
- Abnormal shape of the nails
- Abnormal shape of the teeth
- Abnormal shape of the ears
- Abnormal shape of the eyes
- Abnormal shape of the nose
- Abnormal shape

Spondylometaphyseal dysplasia, A4 type is caused by a mutation in the COL2A1 gene. This gene provides instructions for making a protein called type II collagen, which is a major component of cartilage. Mutations in the COL2A1 gene lead to the production of an abnormal form of type II collagen, which disrupts the normal development of bones and other connective tissues.

The treatment for Spondylometaphyseal dysplasia, A4 type, is primarily supportive and symptomatic. Treatment may include physical therapy to help maintain range of motion and muscle strength, orthopedic braces to help support weakened bones, and medications to help manage pain. Surgery may be recommended in some cases to correct skeletal deformities or to stabilize the spine.

1. Genetic mutation: Spondylometaphyseal dysplasia, A4 type is caused by a mutation in the COL2A1 gene.

2. Family history: Individuals with a family history of the disorder are at an increased risk of developing the condition.

3. Age: The condition is more common in children and adolescents.

4. Gender: Spondylometaphyseal dysplasia, A4 type is more common in males than females.

5. Ethnicity: The condition is more common in individuals of African descent.

There is no cure for Spondylometaphyseal dysplasia, A4 type. Treatment focuses on managing the symptoms and complications associated with the condition. This may include physical therapy, medications to reduce pain and inflammation, and surgery to correct skeletal deformities.