This is a genetic disorder that negatively affects the bones, skin, and endocrine system. It is called McCune-Albright syndrome (MAS), and it can cause café-au-lait skin pigmentation, scar tissue on the bones (also known as fibrous dysplasia), and irregular function of the hormone-producing glands. With early diagnosis and proper treatment, people can live a normal life, although it is not curable.
Furthermore, this condition negatively affects the child’s height and weight due to bone growth and problems with the endocrine system. Children may also have a specific type of birthmark on the body and experience early puberty. Generally, it is very important to seek medical help if you notice your child experiences symptoms that resemble MAS.
How Common is McCune-Albright Syndrome?
In general, this condition happens rarely, and it accounts for 100,000 to 1,000,000 people in the entire world.
Symptoms
Commonly, people with MAS experience different symptoms because it affects multiple parts of the body. The symptoms may also range from mild to severe. Check some examples below:
Bone Symptoms
One of the most common symptoms of MAS is fibrous dysplasia. This is a condition in which scar tissue forms in the place of normal bone. The scar tissue grows and weakens your bone as the body grows. As a result, some bones may grow irregularly, causing bone fractures. Those who develop MAS may experience mild to severe forms of fibrous dysplasia. Rarely (less than 1%), people with this genetic disorder may develop cancerous bone lesions (tumors). Check for other symptoms below:
- Asymmetrical bone growth of the face
- Loss of mobility
- Bone pain and discomfort
- Rickets or osteomalacia
- Short stature
- Uneven bone growth of the legs
- Scoliosis
Skin Symptoms
Those who are born with MAS may have some patches of skin that are different in color compared to the rest of the body (also known as skin pigmentation). Moreover, these skin patches may have a dark brown color and appear with uneven jagged borders (also called café-au-lait spots). In most cases, these patches appear on only one side of the body, and symptoms become more prevalent with aging.
Endocrine System Symptoms
This genetic condition also affects the endocrine system. It is made of multiple glands that produce hormones vital for proper function and development. However, MAS can cause early puberty (especially in girls, who may begin menstruating by 2 years of age). It often occurs due to excessive female sex hormones (Estrogen) that are released from cysts in the ovaries. In any case, males may also experience early puberty.
In addition, about 50% of people with MAS have an enlarged thyroid gland. In such cases, the thyroid begins to produce excessive amounts of thyroid hormone (hyperthyroidism). As a result, a person may have a fast heart rate, excessive sweating, high blood pressure (hypertension), and weight loss. Check below for other endocrine system symptoms of MAS:
- Increased production of growth hormones by the pituitary gland, which often causes large hands and feet, rounded facial features, and arthritis (acromegaly).
- Cushing’s syndrome – This condition often causes obesity (excessive body weight) and delayed growth because of an increased production of Cortisol (stress hormone) by the adrenal glands.
Causes
This health condition occurs due to a mutation in the GNAS1 gene. It is responsible for controlling the production of proteins that regulate hormone activity. In people with MAS, this abnormal gene causes an enzyme (adenylate cyclase), which is a type of protein that causes increased hormone production and symptoms.
A genetic mutation means there is a change in the DNA that occurs after conception (somatic mutation). It means MAS does not occur due to abnormal genes that are passed from biological parents to their biological children. The genetic mutation in people with MAS occurs randomly, and it does not result from something that their parents did or did not do during pregnancy. Thus, there are no proven cases of people with MAS who have children with the same condition. In normal circumstances, DNA gives the cells instructions on when to grow, multiply, and die. However, in people with a mutation in the GNAS1 gene, the cells receive different instructions.
What Are The Long-term Effects of McCune-Albright Syndrome?
Almost all people who develop MAS will experience some of the following complications. Check some of them below:
- Bone fractures and deformities – It includes recurrent fractures, bone pain, and significant deformities (such as deformity of the femur).
- Mobility problems
- Facial and skull problems (such as facial asymmetry and an increased risk for blindness or deafness) – A complete vision or hearing loss often occurs due to cranial nerve compression.
- Early onset of puberty
- Thyroid dysfunction – About 50% of people with MAS have an enlarged thyroid gland that causes hyperthyroidism.
- An increased level of growth hormone
- Cushing syndrome
- Liver disease – One possible complication is liver dysfunction, but it occurs rarely in people with MAS.
- Osteomalacia – This condition causes reduced Phosphorus in the blood due to renal phosphate wasting.
This article does not contain a full list of complications. In any case, you can talk with your physician about ways to reduce the risk or even prevent the previous complications. Additionally, there is no way to reduce the risk or prevent MAS because the genetic mutation that causes it occurs randomly.
Diagnosis
Mostly, MAS is diagnosed during early childhood. However, the diagnosis starts with a physical examination to check for irregularities linked to the disease. Sometimes, doctors may also ask some questions about your symptoms and medical history to get more clues about the disease. They may also perform some tests to rule out other health conditions that cause similar symptoms. Check some examples below:
- Blood tests – These tests are often done to check endocrine function.
- Genetic tests – This test helps identify the abnormal gene that causes MAS.
- Biopsy – During this procedure, doctors will take a sample of the affected tissue for testing.
- Imaging tests – The following tests are commonly used to get detailed images of different structures and organs in the body. In people with MAS, doctors often perform X-rays and MRI (magnetic resonance imaging) scans.
Treatment
Most of the time, healthcare professionals prescribe different treatments for people with MAS because they depend on several factors. These include the severity of the condition, existing health problems, gender, age, and preferences. Check below some treatment options often prescribed by doctors for people with MAS:
- Bisphosphonates to reduce the risk of bone fractures
- Aromatase inhibitors to treat early puberty
- Antithyroid medicines to treat hyperthyroidism
- Physical and occupational therapies to manage physical symptoms of MAS
- Surgery – During this procedure, surgeons will treat bone growth (such as fibrous dysplasia)
Frequently Asked Questions
When should I see my healthcare provider?
It is recommended to see a doctor if you or your child experiences any of the following symptoms. Examples include:
- Bone growth that causes irregularities in the shape of their bones
- Walking problems
- Early menstruation
- Severe pain in the bones
- Anxiety
- Hyperactivity
- Mood swings
- Sleep disturbances (insomnia), which are often signs of hyperthyroidism
What is the life expectancy of someone with McCune-Albright syndrome?
In most cases, people with MAS have a normal lifespan. However, the prognosis often depends on the severity of the symptoms. In rare cases, people may develop life-threatening complications that significantly reduce their life expectancy.
At what age does McCune-Albright syndrome occur?
Most diagnosed cases are in children aged 3. Furthermore, this genetic disorder mostly causes early puberty in girls. If you have any other questions, ask your healthcare provider.
