Abstract
It has been recently reported that MAS results from an activating somatic mutation of the α subunit of the G protein (Gs α) occurring early in development. Arg201 mutations in Cys or His have been previously described in several patients with MAS. We report molecular analysis of the Gs α gene in DNA extracted from various tissues in 4 patients with MAS.
Patients. Patient 1 is a girl who associated precocious puberty with advanced growth and bone maturation and ovarian cysts, polyostotic fibrous dysplasia, cafe-au-lait spot, and GH-secreting pituitary adenoma. The patient was resistant to LH-RH analog treatment. The 3 other patients presented with various forms of MAS.
Methods. In patient 1 DNA was extracted from peripheral blood leucocytes (PBL), ovarian kystectomy tissue and the cafe-au-lait lesion. For patients 2, 3 and 4 only DNA extracted from PBL was only available. Exons 8 and 9, and intron. 8, of the Gs α subunit gene were amplified by PCR and directly sequenced. These exons contain the known hot-spot sites of activating mutations of the G protein : Arg201 and Gln227.
Results. In the 4 patients, sequences of the two exons from the DNA from PBL were normal. In the DNA extracted from the skin lesion and ovarian tissue of patient 1 there was no mutation within the two studied exons.
Discussion. It was recently reported that majority of MAS patients have a mutation within the Gs α gene; Arg201 → Cys or His. The absence of mutation within the cafe-au-lait lesion and PBL from the studied patients confirms previous reports which indicated that mutation is rarely detected in these tissues. The absence of any alteration in the ovary may be due to the mosaic distribution of the mutation. Absence of thyroid and adrenal dysfunction in patient 1 may account for a mutation occurring relatively late in development which could explain a low percentage of mutated cells even in the affected tissues. The presence of mutation within other exons of the Gs α gene cannot, however, be ruled out.
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Lumbroso, S., Desclaux, F., Lobaccaro, J. et al. ABSENCE OF MUTATION IN THE G PROTEIN as SUBUNIT GENE IN PATIENTS WITH Mc CUNE ALBRIGHT SYNDROME (MAS). Pediatr Res 33 (Suppl 5), S90 (1993). https://doi.org/10.1203/00006450-199305001-00519
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DOI: https://doi.org/10.1203/00006450-199305001-00519