Mutations of the PRKAR1A gene in Cushing's syndrome due to sporadic primary pigmented nodular adrenocortical disease.
Primary pigmented nodular adrenocortical disease (PPNAD) is a cause of ACTH-independent Cushing's syndrome. This condition can be difficult to diagnose because hypercortisolism may be periodic and adrenal imaging may not demonstrate an adrenal tumor. PPNAD can be part of the Carney complex (CNC), an autosomal dominant multiple neoplasia syndrome. Germline mutations of the regulatory subunit R1A of PKA (PRKAR1A) have been observed in about 45% of CNC kindreds. To improve our understanding of sporadic PPNAD and develop a potential diagnostic tool, we investigated the genetics of patients with sporadic and isolated PPNAD. Patients undergoing surgery for bilateral ACTH-independent Cushing's syndrome in whom pathological examination revealed PPNAD were subjected to endocrinological investigations and a systematic search for other manifestations of CNC. The PRKAR1A gene was sequenced using DNA from frozen adrenal tissues and leukocytes from three patients with sporadic isolated PPNAD and using leukocyte DNA from two additional patients. Different inactivating germline mutations of the PRKAR1A gene were found in the five patients. For three cases, study of the parents' DNA demonstrated a de novo mutation. One patient presented with an unusual 2.5-cm macronodule of the right adrenal mimicking an adrenal adenoma. A somatic 16-bp deletion of PRKAR1A gene was also found in this macronodule. Inactivating germline mutations of PRKAR1A are frequent in sporadic and isolated cases of PPNAD. The wild-type allele can be inactivated by somatic mutations, consistent with the hypothesis of the gene being a tumor suppressor gene. Thus, genetic analysis can be of help to the clinician in the diagnosis of this difficult form of adrenal Cushing's syndrome.
Groussin
Lionel
L
Service des Maladies Endocriniennes et Métaboliques, Centre Hospitalier Universitaire (CHU) Cochin, Paris 75014, France.
Jullian
Eric
E
Perlemoine
Karine
K
Louvel
Albert
A
Leheup
Bruno
B
Luton
Jean Pierre
JP
Bertagna
Xavier
X
Bertherat
Jérôme
J
D000293:Adolescent; D000303:Adrenal Cortex Diseases / Q000000981:diagnostic imaging / Q000235:genetics*; D000328:Adult; D002648:Child; D003480:Cushing Syndrome / Q000235:genetics*; D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D009154:Mutation; D010859:Pigmentation Disorders / Q000235:genetics*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit; C517834:PRKAR1A protein, human; D017868:Cyclic AMP-Dependent Protein Kinases; D006854:Hydrocortisone