Overview
McCune Albright syndrome (MAS) is a rare genetic disorder characterized by mosaicism for a post-zygotic activating mutation in the GNAS1 gene, leading to clinical features including polyostotic fibrous dysplasia, café-au-lait skin lesions, and precocious puberty. It often overlaps with Albright hereditary osteodystrophy (AHO), presenting with short stature, brachydactyly, and other skeletal anomalies 123.Diagnosis
Clinical Features: Presence of polyostotic fibrous dysplasia, café-au-lait skin lesions, and characteristic skeletal deformities (e.g., coxa vara, tibial bowing) 2.
Imaging: Radiographic evidence of fibrous dysplasia involving multiple bones 2.
Biochemical Tests: Evaluation for hypophosphatemic rickets through serum phosphate, calcium, and alkaline phosphatase levels 2.
Genetic Testing: Identification of GNAS1 mutation through molecular genetic analysis 3.
Differential Diagnosis: Distinguish from pseudohypoparathyroidism and other causes of skeletal dysplasia 3.Management
Bone Health: Bisphosphonates for managing bone pain and deformities (specific dosing not detailed in abstracts) 2.
Pubertal Management: Gonadotropin-releasing hormone (GnRH) analogs to control precocious puberty (specific dosing not detailed in abstracts) 2.
Rickets Treatment: Active vitamin D analogs (e.g., calcitriol) and phosphate supplementation for hypophosphatemic rickets (specific dosing not detailed in abstracts) 2.
Endocrinological Support: Thyroid hormone replacement if hypothyroidism is present 3.
Orthopedic Interventions: Surgical correction for severe skeletal deformities as needed 2.
Psychosocial Support: Address developmental and psychological needs due to potential mental retardation and social challenges 13.Special Populations
Pediatrics: Early intervention for skeletal deformities and pubertal management is crucial 23.
Comorbidities: Hypothyroidism requires thyroid hormone replacement therapy 3.Key Recommendations
Perform radiographic imaging and biochemical tests to confirm fibrous dysplasia and hypophosphatemic rickets in suspected cases (Evidence: Moderate) 2.
Initiate bisphosphonate therapy for managing bone pain and deformities associated with fibrous dysplasia (Evidence: Moderate) 2.
Use GnRH analogs for the management of precocious puberty in affected children (Evidence: Moderate) 2.
Supplement with active vitamin D and phosphate for hypophosphatemic rickets (Evidence: Moderate) 2.
Consider genetic testing to identify GNAS1 mutations for definitive diagnosis (Evidence: Moderate) 3.
Provide thyroid hormone replacement in patients with coexisting hypothyroidism (Evidence: Moderate) 3.References
1 Caravaglio JV, Gupta R, Weinstein D. Multiple miliary osteoma cutis of the face associated with Albright hereditary osteodystrophy in the setting of acne vulgaris: a case report. Dermatology online journal 2017. link
2 Dutta S, Bagga A. McCune Albright syndrome and hypophosphatemic rickets. Indian journal of pediatrics 1999. link
3 Izraeli S, Metzker A, Horev G, Karmi D, Merlob P, Farfel Z. Albright hereditary osteodystrophy with hypothyroidism, normocalcemia, and normal Gs protein activity: a family presenting with congenital osteoma cutis. American journal of medical genetics 1992. link