McCune-Albright syndrome (MAS)

What is McCune-Albright syndrome (MAS)?

McCune-Albright syndrome is a congenital (present at birth) condition that affects the bones, skin and endocrine (hormone-producing) tissues. People with this disorder develop areas of abnormal, scar-like tissue in their bones, which is known as polyostotic fibrous dysplasia. This can, in turn, lead to fractures, uneven growth and deformity.

Polyostotic fibrous dysplasia can occur in the bones of the face, which leads to asymmetry. It can also occur in the long bones of the body, such as the leg bones. This can lead to limping or scoliosis (abnormal curvature of the spine).

What are the signs and symptoms of McCune-Albright syndrome (MAS)?

Skeletal symptoms

• Facial deformity

• Fractures

• Limping

• Pain when walking

• Progressive curvature of the spine (scoliosis)

• Uneven growth

Endocrine symptoms

• Cushing’s syndrome

• Impaired kidney function

• Increased production of growth hormone

• Precocious (early) puberty

• Testicular abnormalities, such as large testes (in males)

• Thyroid disease

Skin symptoms

• Café-au-lait spots (light brown patches of skin that often appear on only one side of the body and are present at birth)

What are the causes of McCune-Albright syndrome (MAS)?

McCune-Albright syndrome is a hereditary (passed down in families) condition that is caused by a gene mutation.