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McCune-Albright syndrome is a genetic condition that affects bone growth, skin pigmentation and the body’s hormone balance. Bone abnormalities such as easily broken bones, and premature sexual maturity are typical signs of the condition.

Symptoms range in severity

In some cases, the bone abnormalities and hormone problems are severe enough to be obvious in infancy. In other cases, the child seems healthy in all respects. The severity of symptoms or how a child with McCune-Albright syndrome will be affected throughout life is difficult to predict.

There is currently no cure for McCune-Albright syndrome. The symptoms and signs of McCune-Albright syndrome include:

  • polyostotic fibrous dysplasia – the abnormal growth of two or more bones. Bones of the face
  • skull arms
  • legs are commonly affected café au lait birthmarks
  • usually on the abdomen or back – these birthmarks are flat
  • oval-shaped spots with a jagged outline

Café au lait birthmarks are often the first signs of the condition and appear at or shortly after birth. They are light brown (or ‘milk-coffee coloured’) in people with lighter skin. In people with darker skin they may be harder to see symptoms of an overactive thyroid gland (hyperthyroidism).

Some of the complications of McCune-Albright syndrome can include:

  • in rare cases
  • excessive growth (gigantism) because of growth hormone imbalance – the face
  • feet are commonly affected Cushing’s syndrome. The hormone cortisol is made by the adrenal glands
  • which are located on the kidneys

McCune-Albright syndrome may cause enlargement of the adrenal glands and the overproduction of cortisol.

This causes a range of symptoms collectively known as Cushing’s syndrome.

Some of the symptoms may include: arrested growth in childhood

McCune-Albright syndrome is caused by a change in the GNAS1 gene.

The change causes the GNAS1 gene to become more active than usual. The gene change is not inherited from the parents, nor is it present at the time of conception. The change actually occurs in an early cell division in the developing embryo.

As a result, the change is present in some, but not all, cells of the person’s body. This is known as ‘mosaicism’. Despite hormonal irregularities, most women with McCune-Albright syndrome are fertile.

A person with McCune-Albright syndrome cannot pass the condition on to their children. The cause of the genetic change is not known. The tests used to diagnose McCune-Albright syndrome may include: genetic tests.

There is no cure for McCune-Albright syndrome. Treatment may include:

  • hormone therapy or surgery to treat gigantism. Treatment depends on the person’s age
  • general health
  • severity of the symptoms. Specialist doctors may include an orthopaedic surgeon to treat bone problems
  • a plastic surgeon to treat facial deformities
  • an endocrinologist to treat hormone imbalances

If your child has been diagnosed with McCune-Albright syndrome, it may be helpful to speak to a genetic counsellor. Genetic counsellors are health professionals qualified in both counselling and genetics. As well as providing emotional support, they can help you to understand McCune-Albright syndrome and what causes it, and what a diagnosis means for your child’s health and development.

Genetic counsellors are trained to provide information and support that is sensitive to your family circumstances, culture and beliefs. is connected with a wide range of support groups throughout Michigan and United States and can connect you with other individuals and families affected by McCune-Albright syndrome.

Symptoms of McCune-Albright syndrome premature sexual maturity – this can affect girls and boys, but is much more common in girls onset of the menstrual period before the growth of breasts or pubic hair ovarian cysts, which are thought to trigger early menstruation Complications of McCune-Albright syndrome brittle, warped bones (osteoporosis) repeated fractures rickets blindness or deafness due to abnormal growth of skull bones adrenal gland tumours osteitis fibrosa cystica – soft bones that are prone to developing cysts mobility problems or disabilities caused by abnormal bone growth or asymmetry of the skeleton Cushing’s syndrome obesity weight gain around the abdomen wasting of the limbs a hump of fat high on the back round, red and puffy face thin, easily bruised skin slow healing of skin wounds skin ulcers Causes of McCune-Albright syndrome Diagnosis of McCune-Albright syndrome medical history physical examination blood tests to check hormone levels of the thyroid, parathyroid, adrenal glands and pituitary gland x-rays to examine the skeleton bone scan using an injection of radioactive material other scans, such as MRI Treatment for McCune-Albright syndrome medication to manage pain surgery to bolster affected bones with grafts, pins, casts or a combination of procedures treatment with medicines known as bisphosphonates to improve bone density vitamin D supplements to reduce the risk of rickets regular and supervised exercise program to improve bone density physical therapy to maintain or improve joint mobility medication to reduce levels of the female sex hormone oestrogen surgery to remove ovarian cysts surgery to remove abnormal adrenal glands in the case of Cushing’s syndrome hormone therapy or surgery to treat a pituitary tumour Treatment team for people with McCune-Albright syndrome Genetic counselling and McCune-Albright syndrome The Genetic Support Network of Michigan (GSNV) Where to get help Your GP (doctor) Orthopaedic surgeon Plastic surgeon Endocrinologist Genetic Support Network of Michigan (GSNV) (616) 555-0200 Michigann Clinical Genetics Services (VCGS) (616) 555-0400.

Key Points

  • Symptoms range in severity
  • In people with darker skin they may be harder to see symptoms of an overactive thyroid gland (hyperthyroidism)
  • McCune-Albright syndrome may cause enlargement of the adrenal glands and the overproduction of cortisol
  • This causes a range of symptoms collectively known as Cushing’s syndrome
  • Some of the symptoms may include: arrested growth in childhood