McCune–Albright syndrome (MAS)

McCune–Albright syndrome (MAS) is a rare disorder that affects the bones, skin, and some hormone-producing tissues. A genetic disorder causing skin pigmentation, bone abnormalities, and endocrine problems.

Types

There isn’t a strict classification into “types” for MAS. However, MAS can be identified by the specific organs it affects:

  1. Bones (like in fibrous dysplasia)
  2. Skin (causing café-au-lait spots)
  3. Endocrine glands (leading to hormone-related problems)
  4. Classical MAS: The most common form, characterized by all three main symptoms: skin pigmentation, bone issues, and endocrine problems.
  5. Incomplete MAS: Shows some, but not all, of the classic symptoms.

 Causes

Well, MAS is caused by a specific genetic mutation. However, it doesn’t follow typical inheritance patterns. Instead, it arises spontaneously. Thus, instead of 20 causes, there’s mainly one: a mutation in the GNAS gene.

  1. Spontaneous mutation: MAS is not inherited but arises from a mutation in the body’s cells.
  2. Mosaic state: Not all cells have the mutation, which is why symptoms vary.
  3. No known environmental triggers.
  4. Mutation in the GNAS gene: This is the primary cause.
  5. Random occurrence: It’s not inherited from parents.
  6. Mosaic pattern: Only some cells have the mutation.
  7. Early developmental stage: Mutation occurs after fertilization.
  8. It’s not due to lifestyle or diet.
  9. Not linked to parental age.
  10. Not associated with any known toxins.

Symptoms

  1. Café-au-lait spots: Light brown skin patches.
  2. Bone pain or deformity: Especially in the skull, face, thigh, and shin.
  3. Fractures: Bones can break easily.
  4. Early puberty: Girls may start menstruating before age 8.
  5. Goiter: Enlarged thyroid gland.
  6. Hyperthyroidism: Overactive thyroid.
  7. Irregular menstrual periods.
  8. Acromegaly: Abnormal growth of hands and feet due to excess growth hormone.
  9. Cushing syndrome: High levels of cortisol hormone.
  10. Kidney stones: Due to high calcium levels in the urine.
  11. High blood pressure.
  12. Frequent urination.
  13. Ovarian cysts: Fluid-filled sacs on the ovaries.
  14. Testicular abnormalities: In boys, leading to large testicles.
  15. Vision problems: Due to bone abnormalities around the eye.
  16. Hearing loss: Due to bone changes in the ear.
  17. Irregular heartbeat.
  18. Thickened skin.
  19. Abnormal hair growth.
  20. Weight gain or obesity: Especially due to hormonal issues.

Diagnostic Tests

  1. Physical exam: Check for café-au-lait spots and bone deformities.
  2. X-rays: Identify bone abnormalities.
  3. Bone scans: Detect bone abnormalities not seen on X-rays.
  4. Blood tests: Check hormone levels.
  5. Urine tests: Measure hormone byproducts.
  6. MRI or CT scans: View bone or endocrine gland abnormalities.
  7. Ultrasound: Especially for ovarian cysts.
  8. Dexamethasone suppression test: For Cushing syndrome.
  9. Thyroid function tests.
  10. Bone density test: Measure strength of bones.
  11. Electrocardiogram (EKG): For heart issues.
  12. Gonadotropin-releasing hormone (GnRH) test: For early puberty.
  13. Genetic testing: Detect the GNAS mutation.
  14. Biopsy: Taking a sample of tissue.
  15. Ophthalmologic exam: Check vision problems.
  16. Audiometry: Test hearing capabilities.
  17. Hormone stimulation or suppression tests.
  18. Pituitary imaging: Check for tumors or abnormalities.
  19. Thyroid ultrasound: Check for nodules.
  20. Functional imaging: Like PET scans for certain tumors.

Treatments

  1. Bisphosphonates: Strengthen bones.
  2. Surgery: To fix bone deformities.
  3. Hormone therapy: Balance hormone levels.
  4. Pain relievers: For bone pain.
  5. Calcitonin: Slow bone loss.
  6. Gonadotropin-releasing hormone analogs: Treat early puberty.
  7. Methimazole: Treat hyperthyroidism.
  8. Ketoconazole: Reduce cortisol levels.
  9. Radiation therapy: For bone lesions.
  10. Physical therapy: Improve movement and strength.
  11. Bracing: For bone fractures.
  12. Thyroidectomy: Remove part or all of the thyroid.
  13. Pituitary surgery: For tumors.
  14. Ovarian surgery: For cysts.
  15. Radiofrequency ablation: Treat bone lesions.
  16. Denosumab: Treat bone lesions.
  17. Pegvisomant: Treat acromegaly.
  18. Cabergoline: Lower growth hormone production.
  19. Octreotide: Treat acromegaly.
  20. Cryotherapy: For certain bone tumors.
  21. Selective arterial embolization: For bone lesions.
  22. Sclerotherapy: For cysts.
  23. Dietary changes: For those with Cushing syndrome.
  24. Weight management programs.
  25. Monitoring: Regularly check for complications.
  26. Counseling: Psychological support.
  27. Hearing aids: For hearing loss.
  28. Vision aids: For vision problems.
  29. Support groups: For emotional support.
  30. Endocrinologist consultation: Specialists in hormone disorders.

Drugs

  1. Alendronate (Fosamax).
  2. Pamidronate (Aredia).
  3. Zoledronic acid (Zometa).
  4. Risedronate (Actonel).
  5. Letrozole: For early puberty.
  6. Testolactone: For early puberty.
  7. Methimazole (Tapazole).
  8. Propranolol: For hyperthyroid symptoms.
  9. Ketoconazole (Nizoral).
  10. Hydrocortisone: Replace cortisol.
  11. Leuprolide (Lupron).
  12. Triptorelin (Trelstar).
  13. Bicalutamide: Treat precocious puberty.
  14. Flutamide: Another treatment for precocious puberty.
  15. Cabergoline (Dostinex).
  16. Octreotide (Sandostatin).
  17. Pegvisomant (Somavert).
  18. Pasireotide (Signifor).
  19. Bromocriptine (Parlodel).
  20. Goserelin (Zoladex).

In Summary

McCune–Albright syndrome is a complex disorder. This guide gives an overview of its symptoms, diagnosis, and treatment. Regular consultation with a medical specialist ensures the best care.