sufficient to disrupt Gnas imprinting and to result in PTH resistance, ruling out a disrupted STX16 mRNA and/or protein as the molecular cause of familial PHP-Ib. This conclusion, which is consistent with the evidence that the STX16 locus is not imprinted, supports the hypothesis that the deletions in this gene disrupt a cis-acting long-range regulatory element required for the proper imprinting of GNAS exon A/B. It appears that this putative control element is not located within Stx16 exons 4-6 in mice.
