Mutations in PKA catalytic subunit associated with Cushing’s syndrome

Posted on March 18, 2014 by MaryO

1. Somatic mutations resulting in constitutive activation of PRKACA, which encodes the catalytic subunit of protein kinase A, were found in 37% of patients with Cushing’s syndrome due to an adrenal adenoma. 

2. Germline duplications of PRKACA were detected in patients with bilateral adrenal hyperplasia and overt Cushing’s syndrome. 

Study Rundown: This study found that 37% of patients with overt Cushing’s syndrome due to an adrenal adenoma have a somatic mutation in PRKACA, which encodes the catalytic subunit of cyclic AMP-dependent protein kinase A (PKA), present in their tumor cells. The most commonly identified variant, Leu206Arg, results in impaired interaction between the catalytic and regulatory subunits of PKA, thereby causing constitutive activation of PKA. Additionally, a subset of patients with cortisol-producing bilateral adrenal hyperplasia harbored germline duplications of PRKACA.

This is the first study to identify an association between genetic alterations of the catalytic subunit of PKA and Cushing’s syndrome. It is significant that 37% of patients with overt Cushing’s syndrome were found to have tumors with PRKACA mutations; previous research had revealed only very rare mutations. Of note, this study did not find PRKACA mutations in any patients with subclinical Cushing’s syndrome or inactive adenomas. This suggests that Cushing’s syndrome and subclinical Cushing’s are distinct entities. Patients involved in this study were recruited from only three centers; the frequency of PRKACA mutations in Cushing’s syndrome may be different in other study populations. Further research will be needed to identify biochemical causes of overt Cushing’s syndrome in patients without PRKACA mutations.

Relevant Reading: Abnormalities of cAMP signaling are present in adrenocortical lesions associated with ACTH-independent Cushing’s syndrome despite the absence of mutations in known genes

In-Depth: In this study, exome sequencing of tumor specimens from 10 patients with unilateral cortisol-producing adenomas and overt Cushing’s syndrome was performed. Eight of 10 adenomas had somatic mutations in PRKACA; 7 of these patients had the same mutation (p.Leu206Arg). Subsequently, PRKACA was sequenced in 129 additional patients with adrenal adenomas. Patients were classified as having overt Cushing’s syndrome (at least three abnormal biochemical tests or catabolic features plus two abnormal tests), subclinical Cushing’s (at least one abnormal biochemical test without catabolic signs) or as having an inactive adenoma. The Leu206Arg variant was identified in tumor tissue of 14/129 patients and all 14 had overt Cushing’s syndrome. Overall, 37% (22/59) of patients with overt Cushing’s syndrome due to an adenoma had a PRKACA mutation; in contrast, PRKACA mutations were not found in any patients with subclinical Cushing’s or an inactive adenoma. Of 35 patients with overt Cushing’s syndrome due to cortisol-secreting bilateral adrenal hyperplasia, 5 patients had copy-number gains of a region on chromosome 19p that contains PRKACA.

Analysis of holoenzyme structure revealed that the Leu206Arg mutation is located in the active-site cleft of the catalytic subunit of PKA. To evaluate the functional consequences of this mutation, cells were transfected with either nonmutant or variant C-alpha, which encodes the catalytic subunit of PKA. Investigators determined that the mutation causes constitutive activation of the catalytic subunit by impairing interaction with the regulatory subunit of PKA.

From http://www.2minutemedicine.com/mutations-in-pka-catalytic-subunit-associated-with-cushings-syndrome/

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Genetic variations associated with hyperplasias, adenomas of adrenal cortex

Posted on February 27, 2014 by MaryO

Beuschlein F. N Engl J Med. 2014;doi:10.1056/NEJMoa1310359.

Genetic variations of the catalytic subunit of cyclic protein kinase A, or PKA, were linked to the development of bilateral adrenal hyperplasias and unilateral cortisol-producing adrenal adenomas. These effects may activate corticotropin-independent Cushing’s syndrome, according to data published in The New England Journal of Medicine.

“The current study suggests that more than one-third of cortisol-producing adenomas associated with overt Cushing’s syndrome have unique somatic mutations in PRKACA (which encodes the main catalytic subunit of PKA), resulting in constitutive PKA activation,” Felix Beuschlein, MD, of the University of Munich, and colleagues wrote.

The researchers performed an exome sequencing of tumor-tissue specimens from 10 patients with cortisol-producing adrenal adenomas and evaluated their recurrent mutations in candidate genes in 171 additional patients with adrenocortical tumors, according to data.

Somatic mutations in PRKACA were discovered in eight of 10 adenomas. These somatic mutations also were identified in 22 of 59 unilateral adenomas (37%) from patients with overt Cushing’s syndrome; mutations were not detectable in 40 patients with subclinical hypercortisolism or in 82 patients with other adrenal tumors, according to data.

Five of the 35 patients with cortisol-producing hyperplasias appeared to be carriers of the germline duplication of the genomic region on chromosome 19 that includes PRKACA, researchers wrote.

In vitro study data indicated that PKA catalytic subunit genetic mutations impaired inhibition by the PKA regulatory subunit, and cells from patients with germline chromosomal gains appeared to increase the protein levels of the subunit.

“Because PRKACA mediates most of the effects of inactivating PRKAR1A mutations and because mutations of PRKAR1 are associated with a variety of tumors in humans and mice, we would speculate that somatic PRKACA defects might also play a role in other forms of endocrine and nonendocrine tumors,” researchers wrote.

Disclosure: Beuschlein reports financial ties with the European Community, HRA Pharma, Novartis, Viropharma, and Wilhelm-Sander Stiftung.

From http://www.healio.com/endocrinology/adrenal/news/online/%7B22954d9a-0fc9-4e80-b80a-d74bbdfea1a9%7D/genetic-variations-associated-with-hyperplasias-adenomas-of-adrenal-cortex

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Botch-up Costs Doctor an Adrenal Gland

Posted on February 7, 2014 by MaryO

Chennai, India: The state consumer forum has asked a Coimbatore hospital to pay 15 lakh to a doctor whose adrenal gland was surgically removed after a botched-up diagnosis.

In May 2006, A Indumathi, an ophthalmologist, started showing symptoms like rapid weight gain, hypertension, joint pain, puffiness of face and fatigue. She approached Kovai Medical Centre & Hospital in Coimbatore, where the consultant endocrinologist conducted various tests. Her condition was diagnosed as Cushing’s syndrome, a hormonal disorder, and she was advised to undergo surgery for removal of the left adrenal gland.

On September 18, she was operated on. However, the symptoms persisted and the doctor told her it would take some more time to get relief. She waited three more months, but when her condition worsened, she approached the doctor again. He asked her to undergo another surgery for removing her right adrenal gland.

Not willing to take a chance, Indumathi approached Christian Medical College, Vellore, in December, where doctors told her she was suffering from Cushing’s disease, not syndrome. After a month of treatment, she recovered.

She then approached the state commission saying she was misdiagnosed and because of the wrong surgery, she has to regularly go for blood tests for the rest of her life and could develop life-threatening complications. She said she also incurred medical expense of around 5 lakh and had to leave her medical practice for six months.

Denying the charges, the hospital said tests conducted on her showed she was suffering from Cushing’s syndrome. She, being a doctor, was aware of the test reports and gave consent for surgery, it said.

The state consumer disputes redressal commission bench comprising its president Justice(rtd )RRegupati and judicial member J Jayaram, in a recent order, said after a wrong diagnosis and surgery, the hospital should have been more diligent in reassessment but instead suggested removing the right adrenal gland. The bench said the hospital wrongly diagnosed her and removed “a precious, healthy adrenal gland.”

Stating it was a case of “gross negligence and deficiency in service,” the bench asked the hospital and two doctors to pay Indumathi 4 lakh towards medical and travelling expense, 1 lakh for loss of professional income and 10 lakh for “lifelong mental agony.”

From http://timesofindia.indiatimes.com/city/chennai/Botch-up-costs-doctor-a-gland-hospital-fined-Rs-15-lakh/articleshow/29925290.cms

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ARMC5 Mutations in Macronodular Adrenal Hyperplasia with Cushing’s Syndrome

Posted on November 30, 2013 by MaryO

adrenal-hyperplasia

 

Guillaume Assié, M.D., Ph.D., Rossella Libé, M.D., Stéphanie Espiard, M.D., Marthe Rizk-Rabin, Ph.D., Anne Guimier, M.D., Windy Luscap, M.Sc., Olivia Barreau, M.D., Lucile Lefèvre, M.Sc., Mathilde Sibony, M.D., Laurence Guignat, M.D., Stéphanie Rodriguez, M.Sc., Karine Perlemoine, B.S., Fernande René-Corail, B.S., Franck Letourneur, Ph.D., Bilal Trabulsi, M.D., Alix Poussier, M.D., Nathalie Chabbert-Buffet, M.D., Ph.D., Françoise Borson-Chazot, M.D., Ph.D., Lionel Groussin, M.D., Ph.D., Xavier Bertagna, M.D., Constantine A. Stratakis, M.D., Ph.D., Bruno Ragazzon, Ph.D., and Jérôme Bertherat, M.D., Ph.D.

N Engl J Med 2013; 369:2105-2114 November 28, 2013 DOI: 10.1056/NEJMoa1304603

BACKGROUND

Corticotropin-independent macronodular adrenal hyperplasia may be an incidental finding or it may be identified during evaluation for Cushing’s syndrome. Reports of familial cases and the involvement of both adrenal glands suggest a genetic origin of this condition.

METHODS

We genotyped blood and tumor DNA obtained from 33 patients with corticotropin-independent macronodular adrenal hyperplasia (12 men and 21 women who were 30 to 73 years of age), using single-nucleotide polymorphism arrays, microsatellite markers, and whole-genome and Sanger sequencing. The effects of armadillo repeat containing 5 (ARMC5) inactivation and overexpression were tested in cell-culture models.

RESULTS

The most frequent somatic chromosome alteration was loss of heterozygosity at 16p (in 8 of 33 patients for whom data were available [24%]). The most frequent mutation identified by means of whole-genome sequencing was in ARMC5, located at 16p11.2. ARMC5 mutations were detected in tumors obtained from 18 of 33 patients (55%). In all cases, both alleles of ARMC5 carried mutations: one germline and the other somatic. In 4 patients with a germline ARMC5 mutation, different nodules from the affected adrenals harbored different secondary ARMC5 alterations. Transcriptome-based classification of corticotropin-independent macronodular adrenal hyperplasia indicated that ARMC5 mutations influenced gene expression, since all cases with mutations clustered together. ARMC5 inactivation decreased steroidogenesis in vitro, and its overexpression altered cell survival.

CONCLUSIONS

Some cases of corticotropin-independent macronodular adrenal hyperplasia appear to be genetic, most often with inactivating mutations of ARMC5, a putative tumor-suppressor gene. Genetic testing for this condition, which often has a long and insidious prediagnostic course, might result in earlier identification and better management. (Funded by Agence Nationale de la Recherche and others.)

Supported in part by grants from Agence Nationale de la Recherche (ANR-10-Blan-1136), Corticomedullosurrénale Tumeur Endocrine Network (Programme Hospitalier de Recherche Clinique grant AOM95201), Assistance Publique–Hôpitaux de Paris (Clinical Research Center Grant Genhyper P061006), Institut National du Cancer (Recherche Translationelle 2009-RT-02), the Seventh Framework Program of the European Commission (F2-2010-259735), INSERM (Contrat d’Interface, to Dr. Assié), the Conny-Maeva Charitable Foundation, and the intramural program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development.

Disclosure forms provided by the authors are available with the full text of this article at NEJM.org.

Drs. Assié, Libé, Espiard, Rizk-Rabin, Ragazzon, and Bertherat contributed equally to this article.

We thank Drs. J. Chelly and M. Delpech of the cell bank of Cochin Hospital and Dr. B. Terris of the tumor bank of Cochin Hospital for their help in sample collection; Dr. E. Clauser of the oncogenetic unit of Cochin Hospital for help in microsatellite analysis; Drs. J. Guibourdenche and E. Clauser of the hormone biology unit of Cochin Hospital for cortisol assays; Drs. F. Tissier and Pierre Colin for pathological analysis; Anne Audebourg for technical assistance; J. Metral and A. de Reynies of the Cartes d’Identité des Tumeurs program of Ligue Nationale contre le Cancer for help in genomics studies and fruitful discussions; Dr. P. Nietschke of the bioinformatics platforms of Paris Descartes University for helpful discussions; all the members of the Genomics and Signaling of Endocrine Tumors team and of the genomic platform of Cochin Institute for their help in these studies; and the patients and their families, as well as the physicians and staff involved in patient care, for their active participation.

SOURCE INFORMATION

From INSERM Unité 1016, Centre National de la Recherche Scientifique Unité Mixte de Recherche 8104, Institut Cochin (G.A., R.L., S.E., M.R.-R., A.G., W.L., O.B., L.L., S.R., K.P., F.R.-C., F.L., L. Groussin, X.B., B.R., J.B.), Faculté de Médecine Paris Descartes, Université Paris Descartes, Sorbonne Paris Cité (G.A., S.E., A.G., O.B., L.L., M.S., K.P., F.R.-C., L. Groussin, X.B., J.B.), Department of Endocrinology, Referral Center for Rare Adrenal Diseases (G.A., R.L., O.B., L. Guignat, L. Groussin, X.B., J.B.), and Department of Pathology (M.S.), Assistance Publique–Hôpitaux de Paris, Hôpital Cochin, and Unit of Endocrinology, Department of Obstetrics and Gynecology, Hôpital Tenon (N.C.-B.) — all in Paris; Unit of Endocrinology, Centre Hospitalier du Centre Bretagne, Site de Kério, Noyal-Pontivy (B.T.), Unit of Endocrinology, Hôtel Dieu du Creusot, Le Creusot (A.P.), and Department of Endocrinology Lyon-Est, Groupement Hospitalier Est, Bron (F.B.-C.) — all in France; and the Section on Endocrinology and Genetics, Program on Developmental Endocrinology and Genetics and the Pediatric Endocrinology Inter-Institute Training Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD (C.A.S.).

Address reprint requests to Dr. Bertherat at Service des Maladies Endocriniennes et Métaboliques, Centre de Référence des Maladies Rares de la Surrénale, Hôpital Cochin, 27 rue du Faubourg St. Jacques, 75014 Paris, France, or at jerome.bertherat@cch.aphp.fr.

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Are you carrying adrenal Cushing’s syndrome without knowing it?

Posted on November 28, 2013 by MaryO

Genetic research that will be published tomorrow in the New England Journal of Medicine suggests to Dr. André Lacroix, professor at the University of Montreal, that clinicians’ understanding and treatment of a form of Cushing’s syndrome affecting both adrenal glands will be fundamentally changed, and that moreover, it might be appropriate to begin screening for the genetic mutations that cause this form of the disease.

“Screening family members of bilateral adrenal Cushing’s syndrome patients with  may identify affected silent carriers,” Lacroix said in an editorial in the Journal. “The development of drugs that interrupt the defective genetic chemical link that causes the syndrome could, if confirmed to be effective in people, provide individualized specific therapies for hypercortisolism, eliminate the current practice of removing both , and possibly prevent disease progression in genetically affected .”

Adrenal glands sit above the kidneys are mainly responsible for releasing cortisol, a stress hormone. Hypercortiolism means a high level of the adrenal hormone cortisol, which causes many symptoms including weight gain, , diabetes, osteoporosis, concentration deficit and increased cardiovascular deaths.

Cushing’s syndrome can be caused by corticosteroid use (such as for asthma or arthritis), a tumor on the adrenal glands, or a  that releases too much ACTH. The pituitary gland sits under the brain and releases various hormones that regulate our bodies’ mechanisms.

Jérôme Bertherat is a researcher at Cochin Hospital in Paris. In the study he published today, he showed that 55% of Cushing’s Syndrome patients with bilaterally very enlarged adrenal glands have mutations in a gene that predisposes to the development of adrenal tumours. This means that bilateral adrenal Cushing’s is much more hereditary than previously thought. The new knowledge will also enable clinicians to undertake genetic screening. Hervé Lefebvre is a researcher at the University Hospital in Rouen, France. His research shows that the adrenal glands from the same type of patients with two large adrenal glands can produce ACTH, which is normally produced by the pituitary gland. Hormone receptors are the chemical link that cause a cell to behave differently when a hormone is present. Several misplaced hormone receptors cause the ACTH to be produced in the enlarged benign adrenal tissue. Knowing this means that researchers might be able to develop drugs that interrupt the receptors for these hormones and possibly even prevent the benign tissue from developing in the first place.

 Explore further: Scientists discover a curable cause for some cases of high blood pressure

More information: André Lacroix, M.D., Heredity and Cortisol Regulation in Bilateral Macronodular Adrenal Hyperplasia, New England Journal of Medicine 369;22, November 28, 2013

Estelle Louiset, Ph.D., Céline Duparc, Ph.D., Jacques Young, M.D., Ph.D., Sylvie Renouf, Ph.D., Milène Tetsi Nomigni, M.Sc., Isabelle Boutelet, Ph.D., Rossella Libé, M.D., Zakariae Bram, M.Sc., Lionel Groussin, M.D., Ph.D., Philippe Caron, M.D., Antoine Tabarin, M.D., Ph.D., Fabienne Grunenberger, M.D., Sophie Christin-Maitre, M.D., Ph.D., Xavier Bertagna, M.D., Ph.D., Jean-Marc Kuhn, M.D., Youssef Anouar, Ph.D., Jérôme Bertherat, M.D., Ph.D., and Hervé Lefebvre, M.D., Ph.D., Intraadrenal Corticotropin in Bilateral Macronodular Adrenal Hyperplasia, New England Journal of Medicine 369;22, November 28, 2013

Guillaume Assié, M.D., Ph.D., Rossella Libé, M.D., Stéphanie Espiard, M.D., Marthe Rizk-Rabin, Ph.D., Anne Guimier, M.D., Windy Luscap, M.Sc., Olivia Barreau, M.D., Lucile Lefèvre, M.Sc., Mathilde Sibony, M.D., Laurence Guignat, M.D., Stéphanie Rodriguez, M.Sc., Karine Perlemoine, B.S., Fernande René-Corail, B.S., Franck Letourneur, Ph.D., Bilal Trabulsi, M.D., Alix Poussier, M.D., Nathalie Chabbert-Buffet, M.D., Ph.D., Françoise Borson-Chazot, M.D., Ph.D., Lionel Groussin, M.D., Ph.D., Xavier Bertagna, M.D., Constantine A. Stratakis, M.D., Ph.D., Bruno Ragazzon, Ph.D., and Jérôme Bertherat, M.D., Ph.D., ARMC5 Mutations in Macronodular Adrenal Hyperplasia with Cushing’s Syndrome, New England Journal of Medicine 369;22, November 28, 2013

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