Cardiac myxomas are benign mesenchymal tumors that can present as components of the human autosomal dominant disorder Carney complex. Syndromic cardiac myxomas are associated with spotty pigmentation of the skin and endocrinopathy. Our linkage analysis mapped a Carney complex gene defect to chromosome 17q24. We now demonstrate that the PRKAR1α gene encoding the R1α regulatory subunit of cAMP-dependent protein kinase A (PKA) maps to this chromosome 17q24 locus. Furthermore, we show that PRKAR1α frameshift mutations in three unrelated families result in haploinsufficiency of R1α and cause Carney complex. We did not detect any truncated R1α protein encoded by mutant PRKAR1α. Although cardiac tumorigenesis may require a second somatic mutation, DNA and protein analyses of an atrial myxoma resected from a Carney complex patient with a PRKAR1α deletion revealed that the myxoma cells retain both the wild-type and the mutant PRKAR1α alleles and that wild-type R1α protein is stably expressed. However, in this atrial myxoma, we did observe a reversal of the ratio of R1α to R2β regulatory subunit protein, which may contribute to tumorigenesis. Further investigation will elucidate the cell-specific effects of PRKAR1α haploinsufficiency on PKA activity and the role of PKA in cardiac growth and differentiation.
Mairead Casey, Carl J. Vaughan, Jie He, Cathy J. Hatcher, Jordan M. Winter, Stanislawa Weremowicz, Kate Montgomery, Raju Kucherlapati, Cynthia C. Morton, Craig T. Basson
Guidelines: The Editorial Board will only consider letters that we deem relevant and of interest to our readers. We will not post data that have not been subjected to peer review, nor will we post letters that are essentially a reiteration of another letter. All accepted letters will be posted on our website within one week of acceptance. We reserve the right to edit any letter for length, content, and clarity. Authors of all accepted letters will be asked to preview any changes. Authors will be notified by e-mail if their letters were not accepted. As this is a final decision, no appeals will be considered.
Specific requirements: All letters must be 400 words or fewer. You may enter the letter as plain text or HTML. The author's name and e-mail address are required, and will be posted with the letter. All possible conflicts of interest must be noted, even if they are not posted. If you wish to include a figure (keep in mind that non-peer-reviewed data will not be posted), please contact the editors directly at firstname.lastname@example.org.