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Albright hereditary osteodystrophy (AHO) is characterized by multiple somatic defects secondary to mutations in the GNAS1 gene. AHO patients with mutations on maternally inherited alleles are resistant to multiple hormones (e.g., PTH, TSH), a variant termed pseudohypoparathyroidism (PHP) type 1a, due to presumed tissue-specific paternal imprinting of the α chain of G_s as demonstrated in murine renal proximal tubule and fat cells. Studies in human tissues thus far revealed imprinting only in pituitary. Because mild hypothyroidism due to TSH resistance occurs in most PHP type 1a patients, we investigated whether Gα_s is imprinted in thyroid. Examination of eight normal thyroids demonstrated significantly greater expression from the maternal GNAS1 allele, with paternal Gα_s transcripts accounting for only 25.9–40.4%. Expression of NESP55, XLα_s, and 1A was uniallelic. We conclude that Gα_s is incompletely …