McCune-Albright Syndrome
Description
McCune-Albright Syndrome (MAS) is a rare genetic disorder that affects various parts of the body, including bones, skin, and endocrine system. It‘s characterized by a unique combination of symptoms that can vary widely in severity and impact on individuals‘ lives. This blog delves into the intricacies of MAS, shedding light on its causes, recognizing its signs and symptoms, and exploring strategies for managing this complex condition.
Genes Involved
McCune-Albright Syndrome is caused by a mutation in the GNAS gene. This gene provides instructions for making a protein called the alpha subunit of the stimulatory G protein, which is involved in various cellular processes, including hormone signaling.
Recognizing the Signs and Symptoms
McCune-Albright Syndrome presents a distinctive triad of symptoms:
- Fibrous Dysplasia: This condition affects bone development, causing bones to become abnormally weak and prone to fractures. It often affects the skull, ribs, and long bones.
- Cafe-au-lait Spots: These are light brown or tan-colored skin patches that are typically larger than freckles and can vary in size and number. They are often irregular in shape with a "coast of Maine" appearance.
- Endocrine Dysfunction: This refers to problems with the glands that produce hormones. The most common endocrine abnormality associated with MAS is precocious puberty, which occurs when a child begins puberty earlier than expected. Other endocrine issues may include hyperthyroidism (overactive thyroid), hypercortisolism (Cushing‘s syndrome), or acromegaly (excess growth hormone).
Causes
MAS arises from a post-zygotic mutation, which means the mutation occurs after fertilization, affecting only a portion of the body‘s cells. This explains the mosaic pattern of symptoms observed in individuals with MAS. The mutation leads to excessive production of the G protein alpha subunit, disrupting normal cell function and causing the characteristic symptoms.
Inheritance/recurrence risk
McCune-Albright Syndrome is not inherited from parents. The mutation is sporadic, meaning it occurs randomly during early embryonic development. As a result, there is no risk of passing the condition on to children. However, the mutation can be passed on to offspring if the individual with MAS has children through germline mosaicism (where some reproductive cells carry the mutation).
