Albright hereditary osteodystrophy
The disease is cause by mutations or imprinting defects in the GNAS1 gene. The syndrome is characterized by pseudohypoparathyroidism and skeletal abnormalities associated sometimes with mental retardation.
The clinical symptoms of Albright hereditary osteodystrophy (AHO) include pseudohypoparathyroidism (PHP) (renal parathyroid hormone resistance) and disturbances of skeletal development (short stature, obesity, round face, intramembranous ossifications, brachydactyly, and other). PTH resistance accounts for hypocalcemia and hyperphosphatemia which is not amenable to PTH treatment.
The imprinting mechanism of this gene brings about that the disease occurs only when it is passed by a mother with mild clinical symptoms or a de novo mutation of the maternal allele. If the mutation is paternally inherited the symptoms are usually milder and the laboratory findings (calcium and phosphate) are normal. This condition is named pseudopseudohypoparathyroidism (PPHP).