Carney complex (CNC) is a familial multiple neoplasia syndrome characterized by cardiac and extracardiac myxomas in the setting of spotty skin pigmentation and endocrinopathy. We previously identified
PRKAR1A
(regulatory subunit 1α of protein kinase A) mutations in CNC. Mutational analyses of the
PRKAR1A
gene in 51 unrelated CNC probands now detect mutations in 65%. All mutations, except for one unique missense mutation, lead to
PRKAR1A
haploinsufficiency. Therefore, we studied the consequences of
prkar1a
haploinsufficiency in mice. Although we did not observe cardiac myxomas or altered pigmentation in
prkar1a
+/–
mice, we did observe some phenotypes similar to CNC, including altered heart rate variability. Moreover,
prkar1a
+/–
mice exhibited a marked propensity for extracardiac tumorigenesis. They developed sarcomas and hepatocellular carcinomas. Sarcomas were frequently associated with myxomatous differentiation. Tumors from
prkar1a
+/–
mice did not exhibit
prkar1a
loss of heterozygosity. Thus, we conclude that although PRKAR1A haploinsufficiency does predispose to tumorigenesis, distinct secondary genetic events are required for tumor formation.