Germline PRKACA amplification-associated primary pigmented nodular adrenocortical disease: a case report and literature review

Primary pigmented nodular adrenocortical disease (PPNAD) is a rare adrenocorticotropin hormone (ACTH)-independent Cushing's syndrome (CS). Pediatric patients with PPNAD typically have unusual skin lesions and slow growth with unknown causes. We present a case of a female Chinese patient with PPNAD caused by the germline PRKACA gene copy number gain of chromosome 19. The patient initially presented with kidney stones, short stature, and obesity. After further testing, it was discovered that the patient had diabetes, mild hypertension, low bone mass, a low ACTH level, and hypercortisolemia, and neither the low-dose or high-dose dexamethasone suppression test was able to inhibit hematuric cortisol, which paradoxically increased. PPNAD was pathologically diagnosed after unilateral adrenalectomy. Chromosome microarrays and whole exon sequencing analyses of the peripheral blood, as well as testing of sectioned adrenal tissue, showed a rise in the copy number of the duplication-containing PRKACA gene on chromosome 19p13.13p13.12, a de novo but not heritable gene defect that causes disease. The clinical signs and symptoms supported the diagnosis of Carney complex (CNC). One significant mechanism of CNC pathogenesis may be the rise in germline PRKACA copy number of chromosome 19. When assessing PPNAD patients for CNC, the possibility of PRKACA gene amplification should be considered. The effect of PRKACA gene amplification on the clinical manifestations of CNC needs to be confirmed by more cases.

Adrenal hyperplasias in childhood: An update

Pediatric adrenocortical hyperplasias are rare; they usually present with Cushing syndrome (CS); of them, isolated micronodular adrenal disease and its variant, primary pigmented adrenocortical disease are the most commonly encountered. Most cases are due to defects in the cyclic AMP/protein kinase A (cAMP/PKA) pathway, although a few cases remain without an identified genetic defect. Another cause of adrenal hyperplasia in childhood is congenital adrenal hyperplasia, a group of autosomal recessive disorders that affect steroidogenic enzymes in the adrenal cortex. Clinical presentation varies and depends on the extent of the underlying enzymatic defect. The most common form is due to 21-hydroxylase deficiency; it accounts for more than 90% of the cases. In this article, we discuss the genetic etiology of adrenal hyperplasias in childhood.

Carney Complex Complicated with Primary Pigmented Nodular Adrenocortical Disease without Cushing's Syndrome Recurrence for Five Years after Unilateral Adrenalectomy

We herein report a case of Carney complex (CNC) complicated with primary pigmented nodular adrenocortical disease (PPNAD) after unilateral adrenalectomy. A 44-year-old woman was admitted to our hospital for PPNAD surgery. She had previously undergone surgery for cardiac myxoma and had a PRKAR1A mutation with no family history of CNC. She had Cushing's signs, but her metabolic abnormalities were mild. Adrenal insufficiency due to poor medication adherence was a concern, so she underwent unilateral adrenalectomy. Cushing's signs improved postoperatively and without recurrence for five years. Treatment plans for PPNAD should be determined based on the patient's condition, medication adherence, and wishes.

Update of Genetic and Molecular Causes of Adrenocortical Hyperplasias Causing Cushing Syndrome

Bilateral hyperplasias of the adrenal cortex are rare causes of chronic endogenous hypercortisolemia also called Cushing syndrome. These hyperplasias have been classified in two categories based on the adrenal nodule size: the micronodular types include Primary Pigmented Nodular Adrenocortical Disease (PPNAD) and isolated Micronodular Adrenal Disease (iMAD) and the macronodular also named Primary Bilateral Macronodular Adrenal Hyperplasia (PBMAH). This review discusses the genetic and molecular causes of these different forms of hyperplasia that involve mutations and dysregulation of various regulators of the cAMP/protein kinase A (PKA) pathway. PKA signaling is the main pathway controlling cortisol secretion in adrenocortical cells under ACTH stimulation. Although mutations of the regulatory subunit R1α of PKA (PRKAR1A) is the main cause of familial and sporadic PPNAD, inactivation of two cAMP-binding phosphodiesterases (PDE11A and PDE8B) are associated with iMAD even if they are also found in PPNAD and PBMAH cases. Interestingly, PBMAH that is observed in multiple familial syndrome such as APC, menin, fumarate hydratase genes, has initially been associated with the aberrant expression of G-protein coupled receptors (GPCR) leading to an activation of cAMP/PKA pathway. However, more recently, the discovery of germline mutations in Armadillo repeat containing protein 5 (ARMC5) gene in 25-50% of PBMAH patients highlights its importance in the development of PBMAH. The potential relationship between ARMC5 mutations and aberrant GPCR expression is discussed as well as the potential other causes of PBMAH.

A Gene-Based Classification of Primary Adrenocortical Hyperplasias

Primary or adrenocorticotropin-independent adrenocortical tumors and hyperplasias represent a heterogeneous group of adrenocortical neoplasms that arise from various genetic defects, either in isolation or familial. The traditional classification as adenomas, hyperplasias, and carcinomas is non-specific. The recent identification of various germline and somatic genes in the development of primary adrenocortical hyperplasias has provided important new insights into the molecular pathogenesis of adrenal diseases. In this new era of personalized care and genetics, a gene-based classification that is more specific is required to assist in the understanding of their disease processes, hormonal functionality and signaling pathways. Additionally, a gene-based classification carries implications for treatment, genetic counseling and screening of asymptomatic family members. In this review, we discuss the genetics of benign adrenocorticotropin-independent adrenocortical hyperplasias, and propose a new gene-based classification system and diagnostic algorithm that may aid the clinician in prioritizing genetic testing, screening and counseling of affected, at risk individuals and their relatives.

A Novel Mutation in the type Iα Regulatory Subunit of Protein Kinase A (PRKAR1A) in a Cushing's Syndrome Patient with Primary Pigmented Nodular Adrenocortical Disease

A 40-year-old man presented with Cushing's syndrome due to bilateral adrenal hyperplasia with multiple nodules. Computed tomography scan results were atypical demonstrating an enlargement of the bilateral adrenal glands harboring multiple small nodules, but the lesion was clinically diagnosed to be primary pigmented nodular adrenocortical disease (PPNAD) based on both endocrinological test results and his family history. We performed bilateral adrenalectomy and confirmed the diagnosis histologically. An analysis of the patient and his mother's genomic DNA identified a novel mutation in the type Iα regulatory subunit of protein kinase A (PRKAR1A) gene; p.E17X (c.49G>T). This confirmed the diagnosis of PPNAD which is associated with Carney Complex.

ARMC5 Mutations in a Large Cohort of Primary Macronodular Adrenal Hyperplasia: Clinical and Functional Consequences

CONTEXT

Primary bilateral macronodular adrenal hyperplasia (PBMAH) is a rare cause of primary adrenal Cushing's syndrome (CS). ARMC5 germline mutations have been identified recently in PBMAH.

OBJECTIVE

To determine the prevalence of ARMC5 mutations and analyze genotype-phenotype correlation in a large cohort of unrelated PBMAH patients with subclinical or clinical CS.

PATIENTS AND METHODS

ARMC5 was sequenced in 98 unrelated PBMAH index cases. PBMAH was identified by bilateral adrenal nodular enlargement on computed tomography scan. The effect on apoptosis of ARMC5 missense mutants was tested in H295R and HeLa cells. Clinical and hormonal data were collected including midnight and urinary free cortisol levels, ACTH, androgens, renin/aldosterone ratio, cortisol after overnight dexamethasone suppression test, cortisol and 17-hydroxyprogesterone after ACTH 1-24 stimulation and illegitimate receptor responses. Computed tomography and histological reports were analyzed.

RESULTS

ARMC5-damaging mutations were identified in 24 patients (26%). The missense mutants and the p.F700del deletion were unable to induce apoptosis in both H295R and HeLa cell lines, unlike the wild-type gene. ARMC5-mutated patients showed an overt CS more frequently, compared to wild-type patients: lower ACTH, higher midnight plasma cortisol, urinary free cortisol, and cortisol after dexamethasone suppression test (P = .003, .019, .006, and <.001, respectively). Adrenals of patients with mutations were bigger and had a higher number of nodules (P = .001 and <.001, respectively).

CONCLUSIONS

ARMC5 germline mutations are common in PBMAH. Index cases of mutation carriers show a more severe hypercortisolism and larger adrenals. ARMC5 genotyping may help to identify clinical forms of PBMAH better and may also allow earlier diagnosis of this disease.

Molecular and clinical evidence for an ARMC5 tumor syndrome: concurrent inactivating germline and somatic mutations are associated with both primary macronodular adrenal hyperplasia and meningioma

CONTEXT

Primary macronodular adrenal hyperplasia (PMAH) is a rare cause of Cushing's syndrome, which may present in the context of different familial multitumor syndromes. Heterozygous inactivating germline mutations of armadillo repeat containing 5 (ARMC5) have very recently been described as cause for sporadic PMAH. Whether this genetic condition also causes familial PMAH in association with other neoplasias is unclear.

OBJECTIVE

The aim of the present study was to delineate the molecular cause in a large family with PMAH and other neoplasias.

PATIENTS AND METHODS

Whole-genome sequencing and comprehensive clinical and biochemical phenotyping was performed in members of a PMAH affected family. Nodules derived from adrenal surgery and pancreatic and meningeal tumor tissue were analyzed for accompanying somatic mutations in the identified target genes.

RESULTS

PMAH presenting either as overt or subclinical Cushing's syndrome was accompanied by a heterozygous germline mutation in ARMC5 (p.A110fs*9) located on chromosome 16. Analysis of tumor tissue showed different somatic ARMC5 mutations in adrenal nodules supporting a second hit hypothesis with inactivation of a tumor suppressor gene. A damaging somatic ARMC5 mutation was also found in a concomitant meningioma (p.R502fs) but not in a pancreatic tumor, suggesting biallelic inactivation of ARMC5 as causal also for the intracranial meningioma.

CONCLUSIONS

Our analysis further confirms inherited inactivating ARMC5 mutations as a cause of familial PMAH and suggests an additional role for the development of concomitant intracranial meningiomas.

A rare case of familial Cushing's syndrome with a common presentation of weight gain due to a mutation of the PRKAR1A gene causing isolated primary pigmented nodular adrenocortical disease

BACKGROUND

Cushing's syndrome (CS) is uncommon in childhood and adolescence. Variable presentation with subtle symptoms and signs can make diagnosis difficult.

CASE REPORT

We report the case of a 17-year-old girl referred for acne and progressive weight gain with an adrenocorticotropic hormone-independent CS. A computed tomography scan of the adrenals showed normal-sized adrenal glands with discrete bilateral shape irregularity. Bilateral adrenalectomy was performed and the histopathological findings were characteristic of primary pigmented nodular adrenocortical disease (PPNAD). Genetic analysis confirmed a germline mutation of the PRKAR1A gene. The same mutation was found in her sister, mother, and maternal grandfather. Endocrine tests showed that the sister of our patient also presented PPNAD requiring bilateral adrenalectomy and a similar histopathological pattern was observed. No other features of Carney complex was found among all affected members of the family.

CONCLUSION

It is exceptional for PPNAD to be an isolated phenomenon as well as being revealed by progressive weight gain in adolescence.

[A pedigree study of a patient with primary pigmented nodular adrenocortical disease and familial gene mutation]

OBJECTIVE

To clarify the clinical features and genetic background of a kindred of primary pigmented nodular adrenocortical disease (PPNAD).

METHODS

Detailed clinical characteristics and laboratory test results from a ten-year old girl diagnosed as PPNAD were collected. Seven members of her family were screened for Cushing syndrome and Carney complex, and their blood DNA was extracted and sequenced for PRKAR1A, PDE11A, PDE8B and CTNNB1 mutations with ABI3730.

RESULTS

The girl presented with symptoms and signs of hypercortisolism, while no features of Carney complex were observed. Hypercortisolemia, suppressed corticotrophin and high urinary free cortisol level were revealed. Cortisol level could not be suppressed both in high and low dose dexamethasone suppression test. The diagnosis of adrenocorticotrophic hormone (ACTH)-independent Cushing syndrome was established. Image and pathology of adrenal glands were in accordance with PPNAD. Other family members showed no evidence of Cushing syndrome or Carney complex. DNA sequencing showed that the patient harbored a missense mutation, C18G. Her father and younger sister were proved to be carriers of this mutation.

CONCLUSION

A Chinese PPNAD family was identified clinically and genetically, and a novel missense mutation of PRKAR1A was found.

Systematic screening for PRKAR1A gene rearrangement in Carney complex: identification and functional characterization of a new in-frame deletion

BACKGROUND

Point mutations of the PRKAR1A gene are a genetic cause of Carney complex (CNC) and primary pigmented nodular adrenocortical disease (PPNAD), but in 30% of the patients no mutation is detected.

OBJECTIVE

Set up a routine-based technique for systematic detection of large deletions or duplications of this gene and functionally characterize these mutations.

METHODS

Multiplex ligation-dependent probe amplification (MLPA) of the 12 exons of the PRKAR1A gene was validated and used to detect large rearrangements in 13 typical CNC and 39 confirmed or putative PPNAD without any mutations of the gene. An in-frame deletion was characterized by western blot and bioluminescence resonant energy transfer technique for its interaction with the catalytic subunit.

RESULTS

MLPA allowed identification of exons 3-6 deletion in three patients of a family with typical CNC. The truncated protein is expressed, but rapidly degraded, and does not interact with the protein kinase A catalytic subunit.

CONCLUSIONS

MLPA is a powerful technique that may be used following the lack of mutations detected by direct sequencing in patients with bona fide CNC or PPNAD. We report here one such new deletion, as an example. However, these gene defects are not a frequent cause of CNC or PPNAD.

Somatic mutations in ATP1A1 and CACNA1D underlie a common subtype of adrenal hypertension

At least 5% of individuals with hypertension have adrenal aldosterone-producing adenomas (APAs). Gain-of-function mutations in KCNJ5 and apparent loss-of-function mutations in ATP1A1 and ATP2A3 were reported to occur in APAs. We find that KCNJ5 mutations are common in APAs resembling cortisol-secreting cells of the adrenal zona fasciculata but are absent in a subset of APAs resembling the aldosterone-secreting cells of the adrenal zona glomerulosa. We performed exome sequencing of ten zona glomerulosa-like APAs and identified nine with somatic mutations in either ATP1A1, encoding the Na(+)/K(+) ATPase α1 subunit, or CACNA1D, encoding Cav1.3. The ATP1A1 mutations all caused inward leak currents under physiological conditions, and the CACNA1D mutations induced a shift of voltage-dependent gating to more negative voltages, suppressed inactivation or increased currents. Many APAs with these mutations were <1 cm in diameter and had been overlooked on conventional adrenal imaging. Recognition of the distinct genotype and phenotype for this subset of APAs could facilitate diagnosis.

Genetics of adrenocortical disease: an update

PURPOSE OF REVIEW

Disease states characterized by abnormal cellular function or proliferation frequently reflect aberrant genetic information. By revealing disease-specific DNA mutations, we gain insight into normal physiology, pathophysiology, potential therapeutic targets and are better equipped to evaluate an individual's disease risks. This review examines recent advances in our understanding of the genetic basis of adrenal cortical disease.

RECENT FINDINGS

Important advances made in the past year have included identification of KCNJ5 potassium channel mutations in the pathogenesis of both aldosterone-producing adenomas and familial hyperaldosteronism type III; characterization of phosphodiesterase 11A as a modifier of phenotype in Carney complex caused by protein kinase, cAMP-dependent, regulatory subunit, type-I mutations; the finding of 11β-hydroxysteroid dehydrogenase type I mutations as a novel mechanism for cortisone reductase deficiency; and demonstration of potential mortality benefit in pursuing comprehensive presymptomatic screening for patients with Li-Fraumeni syndrome, including possible reduction in risks associated with adrenocortical carcinoma.

SUMMARY

This research review provides a framework for the endocrinologist to maintain an up-to-date understanding of adrenal cortical disease genetics.

Children with Cushing's syndrome: Primary Pigmented Nodular Adrenocortical Disease should always be suspected

Primary Pigmented Nodular Adrenocortical Disease (PPNAD) is a rare form of bilateral adrenocortical hyperplasia that is inherited in an autosomal dominant manner and leads to ACTH-independent Cushing's syndrome (CS). PPNAD may be isolated or associated with Carney Complex (CNC). For the diagnosis of PPNAD and CNC, in addition to the hormonal and imaging tests, searching for PRKAR1A mutations may be recommended. The aims of the present study are to discuss the clinical and molecular findings of two Brazilian patients with ACTH-independent CS due to PPNAD and to show the diagnostic challenge CS represents in childhood. Description of two patients with CS and the many sequential steps for the diagnosis of PPNAD is provided. Sequencing analysis of all coding exons of PRKAR1A in the blood, frozen adrenal nodules (patients 1 and 2) and testicular tumor (patient 1) is performed. After several clinical and laboratory drawbacks that misled the diagnostic investigation in both patients, the diagnosis of PPNAD was finally established and confirmed through pathology and molecular studies. In patient 1, sequencing of PRKAR1A gene revealed a novel heterozygous 10-bp deletion in exon 3, present in his blood, adrenal gland and testicular tumor. The etiologic diagnosis of endogenous CS in children is a challenge that requires expertise and a multidisciplinary collaboration for its prompt and correct management. Although rare, PPNAD should always be considered among the possible etiologies of CS, due to the high prevalence of this disease in this age group.

MicroRNA signature in massive macronodular adrenocortical disease and implications for adrenocortical tumourigenesis

PURPOSE

Massive macronodular adrenocortical disease (MMAD) may be caused by aberrant microRNA expression. To determine the microRNA profile in MMAD and identify putative microRNA-gene target pairs involved in adrenal tumourigenesis.

EXPERIMENTAL DESIGN

We performed microRNA microarray analysis in 10 patients with ACTH-independent Cushing syndrome caused by MMAD (ages 39-60 years) and four normal adrenal cortex samples were used as controls. Microarray data were validated by real-time polymerase chain reaction (qRT-PCR). Identification of potential microRNA-gene target pairs implicated in MMAD pathogenesis has been performed by integrating our microRNA data with previously obtained cDNA microarray data. Experimental validation of specific microRNA gene targets was performed by transfection experiments and luciferase assay.

RESULTS

A total of 37 microRNAs were differentially expressed between MMAD and normal tissues; 16 microRNAs were down-regulated, including miR-200b and miR-203, whereas 21 microRNAs were up-regulated, miR-210 and miR-484 among them. Comparison of microRNA data with different clinicopathological parameters revealed miR-130a and miR-382 as putative diagnostic MMAD markers. Interestingly, we detected miR-200b targeting directly Matrin 3 (MATR3) expression in an adrenocortical cancer cell line (H295R).

CONCLUSIONS

MicroRNAs appear to have distinct regulatory effects in MMAD, including an association with clinical presentation and severity of the disease, expressed by the degree of hypercortisolism. This is the first investigation of microRNAs in MMAD, a disease with complex pathogenesis; the data indicate that specific microRNAs such as miR-200b may play a significant role in MMAD formation and/or progression.

Familial micronodular adrenocortical disease, Cushing syndrome, and mutations of the gene encoding phosphodiesterase 11A4 (PDE11A)

We present the pathologic findings in the adrenal glands of 4 patients, aged 10 to 38 years, with Cushing syndrome and germline inactivating mutations of the gene PDE11A4 that encodes phosphodiesterase11A4. The gene is expressed in the adrenal cortex and catalyses the hydrolysis of cyclic adenosine monophosphate and cyclic guanosine monophosphate. Two of the patients were mother and daughter; the third had no affected relative; the fourth patient inherited the mutation from her father. Three of the group, including the mother and daughter, had the same pathology, primary pigmented nodular adrenocortical disease, a disorder known to be caused by inactivating mutations of the PRKAR1A gene. In these cases, the adrenal glands were small and the pathologic change was deep in the cortex in which numerous pigmented micronodules developed. In the remaining patient, the glands were slightly enlarged primarily owing to a diffuse hyperplasia of the superficial cortex that extended into the epi-adrenal fat.

Association of the M1V PRKAR1A mutation with primary pigmented nodular adrenocortical disease in two large families

BACKGROUND

Carney complex (CNC) is a familial multiple neoplasia syndrome frequently associated with primary pigmented nodular adrenocortical disease (PPNAD), a bilateral form of micronodular adrenal hyperplasia that leads to Cushing's syndrome (CS). Germline PRKAR1A mutations cause CNC and only rarely isolated PPNAD.

PATIENTS AND METHODS

PRKAR1A mutation analysis in two large families with CS and no other CNC manifestations demonstrated a M1V germline mutation; a total of 21 asymptomatic individuals were screened, and mutation carriers were evaluated for CNC. The mutation was expressed in vitro and functionally tested for its effects on protein kinase A function.

RESULTS

Presymptomatic testing identified five first-degree relatives who were M1V carriers and who were all diagnosed with subclinical, mild CS at ages ranging from 20-56 yr. There were no other signs of CNC. In a cell-free system, we detected a shorter compared with the wild-type type 1alpha regulatory subunit of protein kinase A (PRKAR1A) protein (43 kDa). This was not identified in cell lines from the patients or in transfection experiments in HEK293 cells that showed no detectable PRKAR1A protein from the M1V-bearing constructs. In these cells, the mutant mRNA was expressed in a 1:1 ratio.

CONCLUSION

In two large families, the M1V PRKAR1A mutation resulted in a PPNAD-only phenotype with significant variability both in terms of age of onset and clinical severity. Expression studies showed a unique effect of this sequence change. This study has implications for genetic counseling of carriers of this PRKAR1A mutation and patients with CNC and PPNAD and for the study of PRKAR1A-related tumorigenesis.

The paradoxical increase in cortisol secretion induced by dexamethasone in primary pigmented nodular adrenocortical disease involves a glucocorticoid receptor-mediated effect of dexamethasone on protein kinase A catalytic subunits

CONTEXT

Primary pigmented nodular adrenocortical disease (PPNAD) results in most cases from mutations of the protein kinase A (PKA) regulatory subunit 1A (PRKAR1A) gene. Patients with PPNAD exhibit a paradoxical increase in cortisol secretion in response to dexamethasone.

OBJECTIVE

The aim was to investigate the mechanism of the action of dexamethasone on adrenocortical cells removed from patients with PPNAD and a transgenic model of PPNAD [Tg(tTA/X2AS) mice].

DESIGN AND SETTING

We performed an in vitro study in an academic research laboratory.

PATIENTS

Eleven patients with histologically proven PPNAD were included in the study.

INTERVENTION

Cultured PPNAD cells were incubated with dexamethasone in the presence of various modulators of the cAMP/PKA pathway and the glucocorticoid receptor antagonist RU486.

MAIN OUTCOME MEASURE

Cortisol and corticosterone were measured by radioimmunological assays in cell culture supernatants.

RESULTS

Dexamethasone stimulated in vitro cortisol secretion from PPNAD tissues in six patients. The stimulatory effect of dexamethasone on cortisol release was not reduced by the adenylyl cyclase inhibitor SQ22536 or potentiated by the phosphodiesterase inhibitor IMBX and the cAMP analog 8Br-cAMP. Conversely, the PKA inhibitor H89 and RU486 inhibited the cortisol response to dexamethasone. Dexamethasone had no effect on cortisol production from normal human adrenocortical cells but stimulated corticosteroidogenesis in the presence of RU486. Similarly, dexamethasone failed to influence corticosterone release by adrenocortical cells removed from Tg(tTA/X2AS) mice but stimulated corticosteroidogenesis in the presence of RU 486.

CONCLUSIONS

These results indicate that, in human PPNAD tissues, dexamethasone paradoxically stimulates cortisol release through a glucocorticoid receptor-mediated effect on PKA catalytic subunits.

Mutations in regulatory subunit type 1A of cyclic adenosine 5'-monophosphate-dependent protein kinase (PRKAR1A): phenotype analysis in 353 patients and 80 different genotypes

BACKGROUND

The "complex of myxomas, spotty skin pigmentation, and endocrine overactivity," or "Carney complex" (CNC), is caused by inactivating mutations of the regulatory subunit type 1A of the cAMP-dependent protein kinase (PRKAR1A) gene and as yet unknown defect(s) in other gene(s). Delineation of a genotype-phenotype correlation for CNC patients is essential for understanding PRKAR1A function and providing counseling and preventive care.

METHODS

A transatlantic consortium studied the molecular genotype and clinical phenotype of 353 patients (221 females and 132 males, age 34 +/- 19 yr) who carried a germline PRKAR1A mutation or were diagnosed with CNC and/or primary pigmented nodular adrenocortical disease.

RESULTS

A total of 258 patients (73%) carried 80 different PRKAR1A mutations; 114 (62%) of the index cases had a PRKAR1A mutation. Most PRKAR1A mutations (82%) led to lack of detectable mutant protein (nonexpressed mutations) because of nonsense mRNA mediated decay. Patients with a PRKAR1A mutation were more likely to have pigmented skin lesions, myxomas, and thyroid and gonadal tumors; they also presented earlier with these tumors. Primary pigmented nodular adrenocortical disease occurred earlier, was more frequent in females, and was the only manifestation of CNC with a gender predilection. Mutations located in exons were more often associated with acromegaly, myxomas, lentigines, and schwannomas, whereas the frequent c.491-492delTG mutation was commonly associated with lentigines, cardiac myxomas, and thyroid tumors. Overall, nonexpressed PRKAR1A mutations were associated with less severe disease.

CONCLUSION

CNC is genetically and clinically heterogeneous. Certain tumors are more frequent, with specific mutations providing some genotype-phenotype correlation for PRKAR1A mutations.

New genes and/or molecular pathways associated with adrenal hyperplasias and related adrenocortical tumors

Over the course of the last 10 years, we have studied the genetic and molecular mechanisms leading to disorders that affect the adrenal cortex, with emphasis on those that are developmental, hereditary and associated with adrenal hypoplasia or hyperplasia, multiple tumors and abnormalities in other endocrine glands. On the basis of this work, we propose an hypothesis on how adrenocortical tumors form and the importance of the cyclic AMP-dependent signaling pathway in this process. The regulatory subunit type 1-alpha (RIalpha) of protein kinase A (PKA) (the PRKAR1A gene) is mutated in most patients with Carney complex and primary pigmented nodular adrenocortical disease (PPNAD). Phosphodiesterase-11A (the PDE11A gene) and -8B (the PDE8B gene) mutations were found in patients with isolated adrenal hyperplasia and Cushing syndrome, as well in patients with PPNAD. PKA effects on tumor suppression and/or development and the cell cycle are becoming clear: PKA and/or cAMP act as a coordinator of growth and proliferation in the adrenal cortex. Mouse models in which the respective genes have been knocked out see m to support this notion. Genome-wide searches for other genes responsible for adrenal tumors and related diseases are ongoing; recent evidece of the involvement of the mitochondrial oxidation pathway in adrenocortical tumorigenesis is derived from our study of rare associations such as those of disorders predisposing to adrenomedullary and related tumors (Carney triad, the dyad of paragangliomas and gastric stromal sarcomas or Carney-Stratakis syndrome, hereditary leiomyomatosis and renal cancer syndrome) which appear to be associated with adrenocortical lesions.

Case report of familial Carney complex due to novel frameshift mutation c.597del C (p.Phe200LeufsX6) in PRKAR1A

Carney complex is an autosomal dominantly inherited disease characterized by skin pigmentation, myxoma, primary pigmented nodular adrenocortical disease (PPNAD), and acromegaly. However, only a few incidences of PPNAD combined with acromegaly are observed in patients. The type 1alpha regulatory subunit of cAMP-dependent protein kinase (PRKAR1A) has been identified in patients as a causative gene for Carney complex by a positional cloning approach. Here, we report a female patient diagnosed with Cushing's syndrome and a GH-producing pituitary adenoma without otherwise evident acromegaly that could be diagnosed only by specialized endocrinological tests. Based on family history of acromegaly (mother and sister) and the fact that the combination of both diseases is very rare, genetic diagnosis involving Carney complex was considered to be appropriate. The 10 exons and flanking regions of PRKAR1A were screened for mutations by direct DNA sequencing. The patient and her mother and sister were found to have the same, novel frameshift mutation resulting from a single base deletion in exon 6 coding cAMP-binding domain A, denoted c.597delC in PRKAR1A. This single base deletion generated an immature stop codon at the sixth codon (p.Phe200LeufsX6). Even family members with the same mutation can show distinct phenotypes, suggesting that Carney complex is a multifactorial disorder comprising various genetic and environmental factors. Genetic diagnosis makes it possible to prepare more effective therapeutic strategies for patients and gene carriers and to avoid unnecessary tests for non-carriers in the family of the patient.

Detection of somatic beta-catenin mutations in primary pigmented nodular adrenocortical disease (PPNAD)

BACKGROUND

Primary pigmented nodular adrenocortical disease (PPNAD) leads to Cushing syndrome (CS) and is often associated with Carney complex (CNC). Genetic alterations of the type 1-alpha regulatory subunit of cAMP-dependent protein kinase A (PRKAR1A) and phosphodiesterase 11A4 (PDE11A) genes have been found in PPNAD. Recent studies have demonstrated that beta-catenin mutations are frequent in adrenocortical adenomas and carcinomas and that the Wnt-signalling pathway is involved in PPNAD tumorigenesis. We hypothesized that adrenocortical adenomas that form in the context of PPNAD may harbour beta-catenin mutations.

METHODS

We studied 18 patients with CS secondary to PPNAD who were screened for germline PRKAR1A and PDE11A mutations. Tumor DNA was extracted from pigmented adrenocortical adenoma and nodular adrenal hyperplasia. Mutation analysis of exons 3 and 5 of beta-catenin was performed using polymerase chain reaction and direct sequencing. Sections from formalin-fixed, paraffin-embedded tumour samples were studied by immunohistochemistry with an antibody against beta-catenin.

RESULTS

Nine patients were carrying germline PRKAR1A mutations and one patient had a PDE11A mutation. We found somatic beta-catenin mutations in 2 of 18 patients (11%). In both cases, the mutations occurred in relatively large adenomas that had formed in the background of PPNAD. Tumor DNA analysis revealed a heterozygous ACC-to-GCC missense mutation in codon 41 (T41A) and a TCT-to-CCT missense mutation in codon 45 (S45P) of exon 3 of the beta-catenin gene that was confirmed at the cDNA level. There were no alterations in the DNA of PPNAD-adjacent tissues and lymphocytes from the patients, indicating somatic events. Immunohistochemistry showed nuclear accumulation of beta-catenin in more than 90% of cells in adenomatous tissue whereas no nuclear immunoreactivity was detected in adjacent PPNAD nodular cells. Nuclear translocation of beta-catenin protein in the PPNAD adenoma suggests activation of the Wnt-beta-catenin pathway in PPNAD.

CONCLUSIONS

We report, for the first time, beta-catenin mutations in adenomas associated with PPNAD, further implicating Wnt-beta-catenin signalling in tumorigenesis linked to bilateral adrenal hyperplasias.

Expression of progesterone and estradiol receptors in normal adrenal cortex, adrenocortical tumors, and primary pigmented nodular adrenocortical disease

Adrenal tumors occur more frequently in women and are the leading cause of Cushing's syndrome during pregnancy. We aimed to evaluate the potential role of sex steroids in the susceptibility of women to adrenocortical tumors. We evaluated the presence of the progesterone receptor (PR), estradiol receptors (ERs), and aromatase in 5 patients with primary pigmented nodular adrenal disease (PPNAD), 15 adrenocortical adenomas (ACAs) and adjacent normal tissues, 12 adrenocortical carcinomas (ACCs), and 3 normal adrenal glands (NA). The expression of PR and ERalpha was evaluated by enzyme immunoassays, real-time RT-PCR, immunohistochemistry, and cytosol-based ligand-binding assays. ERbeta and aromatase levels were evaluated by real-time RT-PCR. ERalpha concentrations were low in NA, in adrenal tissues adjacent to ACA (51+/-33), in ACC (53+/-78), and lower in ACA (11+/-11 fmol/mg DNA). Conversely, PR concentrations were high in NA and adrenal tissues adjacent to ACA, at 307+/-216 fmol/mg DNA, and were even higher in tumors - 726+/-706 fmol/mg DNA in ACA and 1154+/-1586 fmol/mg DNA in ACC - and in isolated PPNAD nodules. Binding study results in four tumors were compatible with binding to a steroid receptor. In patients with PPNAD, a strong positive immunohistochemical signal was associated with the sole isolated nodular regions. ERbeta transcript levels were very high in all samples except those for two ACCs, whereas aromatase levels were low. PR and ERbeta are clearly present in normal adrenal glands and adrenal tumors. Further studies may shed light on the possible pathogenic role of these receptors in adrenal proliferation.

Protein kinase A subunit expression is altered in Bloom syndrome fibroblasts and the BLM protein is increased in adrenocortical hyperplasias: inverse findings for BLM and PRKAR1A

Bloom syndrome is a genetic disorder associated with chromosomal instability and a predisposition to tumors that is caused by germline mutations of the BLM gene, a RecQ helicase. Benign adrenocortical tumors display a degree of chromosomal instability that is more significant than benign tumors of other tissues. Cortisol-producing hyperplasias, such as primary pigmented nodular adrenocortical disease (PPNAD), which has been associated with protein kinase A (PKA) abnormalities and/or PRKAR1A mutations, also show genomic instability. Another RecQ helicase, WRN, directly interacts with the PRKAR1B subunit of PKA. In this study, we have investigated the PRKAR1A expression in primary human Bloom syndrome cell lines with known BLM mutations and examined the BLM gene expression in PPNAD and other adrenal tumor tissues. PRKAR1A and other protein kinase A (PKA) subunits were expressed in Bloom syndrome cells and their level of expression differed by subunit and cell type. Overall, fibroblasts exhibited a significant decrease in protein expression of all PKA subunits except for PRKAR1A, a pattern that has been associated with neoplastic transformation in several cell types. The BLM protein was upregulated in PPNAD and other hyperplasias, compared to samples from normal adrenals and normal cortex, as well as samples from cortisol- and aldosterone-producing adenomas (in which BLM was largely absent). These data reveal an inverse relationship between BLM and PRKAR1A: BLM deficiency is associated with a relative excess of PRKAR1A in fibroblasts compared to other PKA subunits; and PRKAR1A deficiency is associated with increased BLM protein in adrenal hyperplasias.

Four Japanese patients with adrenal hypoplasia congenita and hypogonadotropic hypogonadism caused by DAX-1 gene mutations: mutant DAX-1 failed to repress steroidogenic acute regulatory protein (StAR) and luteinizing hormone beta-subunit gene promoter activity

Mutations of DSS (dosage sensitive sex reversal)-AHC critical region on the X chromosome, gene 1 DAX-1(NROB1)] results in X-linked adrenal hypoplasia congenita (AHC) and hypogonadotropic hypogonadism (HHG). Here we report four Japanese patients with AHC and HHG caused by the mutations of the DAX-1 gene. All patients manifested adrenal crisis at early childhood. Three patients did not show any pubertal sign and were diagnosed as having HHG. One patient manifested spontaneous pubertal development at 17 years of age. Nevertheless, his puberty did not develop further and his gonadotropin and testosterone levels decreased thereafter. Therefore, he was also diagnosed as having HHG. We performed testicular biopsy in another patient with HHG. Histological examination demonstrated Sertoli cell hypoplasia and no sperm formation in the seminiferous tubules. Molecular analysis demonstrated two novel point mutations (V269D and L278R) in two patients. Transient transfection assays showed that all these mutations (V269D, L271X, L278R, and Q395X) abolished the repression activity to both StAR and LHbeta gene promoter activation. In conclusion, we reported patients with AHC and HHG caused by the loss of function mutations of the DAX-1 gene.

An immortalized human cell line bearing a PRKAR1A-inactivating mutation: effects of overexpression of the wild-type Allele and other protein kinase A subunits

CONTEXT

Inactivating mutations of PRKAR1A, the regulatory subunit type 1A (RIalpha) of protein kinase A (PKA), are associated with tumor formation.

OBJECTIVE

Our objective was to evaluate the role of PKA isozymes on proliferation and cell cycle.

METHODS

A cell line with RIalpha haploinsufficiency due to an inactivating PRKAR1A mutation (IVS2+1 G-->A) was transfected with constructs encoding PKA subunits. Genetics, PKA subunit mRNA and protein expression and proliferation, aneuploidy, and cell cycle status were assessed. To identify factors that mediate PKA-associated cell cycle changes, we studied E2F and cyclins expression in transfected cells and E2F's role by small interfering RNA; we also assessed cAMP levels and baseline and stimulated cAMP signaling in transfected cells.

RESULTS

Introduction of PKA subunits led to changes in proliferation and cell cycle: a decrease in aneuploidy and G(2)/M for the PRKAR1A-transfected cells and an increase in S phase and aneuploidy for cells transfected with PRKAR2B, a known PRKAR1A mutant (RIalphaP), and the PKA catalytic subunit. There were alterations in cAMP levels, PKA subunit expression, cyclins, and E2F factors; E2F1 was shown to possibly mediate PKA effects on cell cycle by small interfering RNA studies. cAMP levels and constitutive and stimulated cAMP signaling were altered in transfected cells.

CONCLUSION

This is the first immortalized cell line with a naturally occurring PRKAR1A-inactivating mutation that is associated in vivo with tumor formation. PKA isozyme balance is critical for the control of cAMP signaling and related cell cycle and proliferation changes. Finally, E2F1 may be a factor that mediates dysregulated PKA's effects on the cell cycle.

Adrenocorticotropic hormone-independent Cushing's syndrome

PURPOSE OF REVIEW

Endogenous Cushing's syndrome is adrenocorticotropic hormone (or corticotropin)-independent in 15-20% of cases. Primary Cushing's syndrome is most often secondary to adrenocortical adenomas or carcinomas, and more rarely to bilateral adrenal hyperplasias. Corticotropin-independent cortisol-producing hyperplasia is caused by micronodular diseases, including primary pigmented nodular adrenocortical disease and nonpigmented micronodular hyperplasia and adrenocorticotropic hormone-independent macronodular adrenal hyperplasia. Primary pigmented nodular adrenocortical disease can be found either alone or in the context of Carney complex, a multiple endocrine neoplasia syndrome.

RECENT FINDINGS

In recent years, the pathophysiology of adrenocortical tumors and hyperplasias became better understood following the identification of genes responsible for syndromes associated with corticotropin-independent Cushing's syndrome and the demonstration of aberrant expression and function of various hormone receptors in adrenocortical adenomas and adrenocorticotropic hormone-independent macronodular adrenal hyperplasia. This article reviews findings on the molecular and genetic aspects of corticotropin-independent Cushing's syndrome including recent gene expression profiling studies of adrenocortical tumors and hyperplasias and animal models that provided clues on the pathogenesis of primary Cushing's syndrome.

SUMMARY

A better understanding of molecular mechanisms involved in adrenocortical tumors and hyperplasias may lead to improved diagnostic and prognostic markers and treatment strategies to assist clinicians in the management of corticotropin-independent Cushing's syndrome.

Adrenocortical tumors, primary pigmented adrenocortical disease (PPNAD)/Carney complex, and other bilateral hyperplasias: the NIH studies

It has been estimated that up to 1 in 10 adults has at least one adrenocortical nodule up to 1 cm on autopsy; these benign tumors may contribute to metabolic syndrome, hypertension, obesity and abnormalities of the hypothalamic-pituitary-adrenal (HPA) axis that can be linked to other serious disorders such as osteoporosis, depression and late-onset diabetes mellitus. In addition, up to 1 in 1500 of these adrenal "incidentalomas" may hide a carcinoma, which, if diagnosed late or left untreated, is associated with significant morbidity and mortality. Consistent with the theme of this symposium, in the present report, we review the efforts undertaken at the National Institutes of Health (NIH) in the last quarter century to unravel the complex clinical genetics and molecular mechanisms involved in adrenal tumorigenesis. We first proposed that adrenocortical tumors form in a molecular sequence of events similar to that in other organs: as the pathology of the tumor increases towards malignancy, genetic changes accumulate. For example, known genetic associations, like TP53 gene changes, occur during the latest stages of adrenocortical tumorigenesis. At the NIH, significant progress has been made in the understanding of the genetics of primary pigmented adrenocortical disease (PPNAD) and other forms of bilateral adrenocortical hyperplasias. This recently led to the identification of phosphodiesterase 11A ( PDE11A) mutations as a low-penetrance predisposing factor to adrenocortical hyperplasias of both the pigmented and non-pigmented variants.

Primary pigmented nodular adrenocortical disease (PPNAD) and pituitary adenoma in a boy with sporadic Carney complex due to a novel, de novo paternal PRKAR1A mutation (R96X)

We report the sporadic case of a 9 year-old boy with Carney syndrome, who presented with precocious puberty due to the endocrinological effects of primary pigmented nodular adrenocortical disease (PPNAD) and a synchronous pituitary adenoma. The adrenal tumor was removed surgically. Following unsuccessful treatment with bromocriptine the pituitary adenoma was also resected and a residual tumor irradiated. Thirty months after diagnosis the boy is free of symptoms. Mutation screening of the entire coding region of the PRKAR1A gene identified five single nucleotide exchanges, four of which were either heterozygous or homozygous polymorphic variants that were also present in his parents. However, the hitherto unreported disease-relevant mutation R96X in exon 3 had occurred de novo on the paternal allele.

[A girl with Cushing's syndrome due to primary pigmented nodular adrenocortical disease]

A 12.5-year-old girl with diabetes mellitus type 1 presented with stunted growth and an increase in body weight. Also, her blood-sugar levels were difficult to manage. An adrenocorticotropin-(ACTH)-independent form of Cushing's syndrome was diagnosed. During the dexamethasone-suppression test, a paradoxical increase in urinary-free cortisol excretion was observed, which is a clear indication of primary pigmented nodular adrenocortical disease (PPNAD). The treatment for patients with PPNAD is bilateral adrenalectomy and hormone substitution. PPNAD may be part of the Carney complex, an autosomal dominant multiple neoplasia syndrome. Screening of family members is mandatory. Further investigation for mutations in the gene encoding the regulatory subunit 1A of the protein kinase A (PRKAR1A) may be helpful.

Depletion of type IA regulatory subunit (RIalpha) of protein kinase A (PKA) in mammalian cells and tissues activates mTOR and causes autophagic deficiency

The human PRKAR1A gene encodes the regulatory subunit 1-alpha (RIalpha) of the cAMP-dependent protein kinase A (PKA) holoenzyme. Regulation of the catalytic activity of PKA is the only well-studied function of RIalpha. Inactivating PRKAR1A mutations cause primary pigmented nodular adrenocortical disease (PPNAD) or Carney complex (CNC), an inherited syndrome associated with abnormal skin pigmentation and multiple neoplasias, including PPNAD. Histochemistry of tissues from CNC patients is indicative of autophagic deficiency and this led us to investigate the relationship between RIalpha and mammalian autophagy. We found that fluorescently tagged RIalpha associates with late endosomes and autophagosomes in cultured cells. The number of autophagosomes in prkar1a-/- mouse embryonic fibroblasts (MEFs) was reduced compared with wild-type MEFs. RIalpha co-immunoprecipitated with mTOR kinase, a major regulator of autophagy. Phosphorylated-mTOR levels and mTOR activity were dramatically increased in prkar1a-/- mouse cells, and in HEK 293 cells with RIalpha levels reduced by siRNA. Finally, phosphorylated-mTOR levels and mTOR activity were increased in CNC cells and in PPNAD tissues. These data suggest that RIalpha deficiency decreases autophagy by the activation of mTOR, providing a molecular basis to autophagic deficiency in PPNAD.

A PRKAR1A mutation associated with primary pigmented nodular adrenocortical disease in 12 kindreds

CONTEXT

Primary pigmented nodular adrenocortical disease (PPNAD), a rare cause of corticotropin-independent Cushing syndrome, can be part of Carney complex (CNC), an autosomal dominant multiple neoplasia syndrome characterized by spotty skin pigmentation, cardiac myxomas, and endocrine tumors or be isolated (i). Germline PRKAR1A-inactivating mutations have been observed in both CNC and iPPNAD, but with no apparent genotype-phenotype correlation.

OBJECTIVE

The objectives of the study were a detailed phenotyping for CNC manifestations in 12 kindreds bearing the same PRKAR1A mutation and a study of the consequences of the mutation and a potential founder effect.

DESIGN

The study consisted of descriptive case reports.

SETTING

The study was conducted at two referral centers.

PATIENTS

The patients described in this study were referred for PRKAR1A gene mutation analysis because of a diagnosis of apparently iPPNAD.

RESULTS

We describe a 6-bp polypyrimidine tract deletion [exon 7 IVS del (-7-->-2)] in 12 unrelated kindreds that were referred for Cushing syndrome due to PPNAD. Nine of the patients had no family history; in two, there was a family history of iPPNAD. Only one patient met the criteria for CNC. Relatives carrying the same mutation had no manifestations of CNC or PPNAD, suggesting a low penetrance of this PRKAR1A defect. A founder effect was excluded by extensive genotyping of chromosome 17 markers.

CONCLUSIONS

In conclusion, a small intronic deletion of the PRKAR1A gene is a low-penetrance cause of mainly iPPNAD; it is the first PRKAR1A genetic defect to have an association with a specific phenotype.

Strategies for the characterization of disorders in cortisol sensitivity

CONTEXT

The clinical presentation of abnormalities in glucocorticoid (GC) sensitivity is diverse, and therefore it is difficult to diagnose this condition.

OBJECTIVE AND DESIGN

The objective of the study was to develop strategies for the characterization of GC sensitivity disorders.

SETTING

The study was conducted in an outpatient clinic.

PATIENTS

Nine patients with GC sensitivity disorders participated.

INTERVENTIONS

Sequence analysis of the GC receptor (GR), determination of GR number per cell, GR ligand-binding affinity, and GR splice regulation were performed in freshly prepared peripheral blood mononuclear lymphocytes and Epstein-Barr virus-transformed lymphoblasts. Cellular GC sensitivity was determined ex vivo by measuring the effect of dexamethasone on GC-induced leucine-zipper and IL-2 mRNA levels and on cell proliferation.

RESULTS

Differences in GR number per cell, GR affinity, GR splice variants, and effects on transactivation or transrepression of GC-sensitive genes were observed between patients and controls. Epstein-Barr virus transformation of lymphoblasts had no influence on GR affinity but increased the GR number 5-fold in healthy controls. In patients diagnosed as cortisol resistant, however, GR number after transformation was increased significantly less than 5-fold, whereas a higher GR number was observed in a patient suspected of cortisol hypersensitivity.

CONCLUSION

This study illustrates several strategies to define abnormalities in GC sensitivity by describing nine patients with affected GC sensitivity, all with a unique clinical course and background.

PRKAR1A mutations in primary pigmented nodular adrenocortical disease

Primary Pigmented Nodular Adrenocortical Disease (PPNAD) is a rare primary bilateral adrenal defect causing corticotropin-independent Cushing's syndrome. It occurs mainly in children and young adults. Macroscopic appearance of the adrenals is characteristic with small pigmented micronodules observed in the cortex. PPNAD is most often diagnosed in patients with Carney complex (CNC), but it can also be observed in patients without other manifestations or familial history (isolated PPNAD). The CNC is an autosomal dominant multiple neoplasia syndrome characterized by the association of myxoma, spotty skin pigmentation and endocrine overactivity. One of the putative CNC genes has been identified as the gene of the regulatory R1A subunit of protein kinase A (PRKAR1A), located at 17q22-24. Germline heterozygous inactivating mutations of PRKAR1A have been reported in about 45% of patients with CNC, and up to 80% of CNC patients with Cushing's syndrome due to PPNAD. Interestingly, such inactivating germline PRKAR1A mutations have also been found in patients with isolated PPNAD. The hot spot PRKAR1A mutation termed c.709[-7-2]del6 predisposes mostly to isolated PPNAD, and is the first clear genotype/phenotype correlation described for this gene. Somatic inactivating mutations of PRKAR1A have been observed in macronodules of PPNAD and in sporadic cortisol secreting adrenal adenomas. Isolated PPNAD is a genetic heterogenous disease, and recently inactivating mutations of the gene of the phosphodiesterase 11A4 (PDE11A4) located at 2q31-2q35 have been identified in patients without PRKAR1A mutations. Interestingly, both PRKAR1A and PDE11A gene products control the cAMP signaling pathway, which can be altered at various levels in endocrine tumors.

Adrenal pathophysiology: lessons from the Carney complex

The Carney complex (CNC) is a dominantly inherited syndrome responsible mainly for spotty skin pigmentation (lentiginosis), endocrine overactivity, and cardiac myxomas. Adrenocorticotropic hormone independent Cushing's syndrome due to primary pigmented nodular adrenocortical disease (PPNAD) is a main characteristic of CNC. PPNAD is a very rare cause of Cushing's syndrome due to a primary bilateral adrenal defect that can be also observed in some patients without other CNC manifestations nor familial history. One of the putative CNC genes, located on 17q22-24, has been identified as the regulatory subunit R1A of protein kinase A (PRKAR1A). Heterozygous inactivating mutations of PRKAR1A have been reported initially in about 45% of the CNC index cases and could be found in about 80% of the CNC families presenting mainly with Cushing's syndrome. PRKAR1A is a key component of the cyclic AMP signaling pathway that has been implicated in endocrine tumorigenesis and could, at least partly, function as a tumor suppressor gene. Interestingly, patients with isolated PPNAD and no familial history of CNC can also present a germline de novo mutation of PRKAR1A. Somatic mutations of PRKAR1A have been found in PPNAD as a mechanism of inactivation of the wild-type allele, in a patient already presenting a germline mutation, and in a subset of sporadic secreting adrenocortical adenomas with clinical, hormonal, and pathological features quite similar to PPNAD. This review will summarize the recent findings on CNC from the perspective of the pathophysiology of adrenal Cushing's syndrome and PPNAD.

Clinical and molecular genetics of primary pigmented nodular adrenocortical disease

Carney complex (CNC) is a multiple endocrine neoplasia (MEN) syndrome associated with other, non-endocrine manifestations such as lentigines, cardiac myxomas and schwannomas. Primary pigmented nodular adrenocortical disease (PPNAD), leading to corticotrophin-independent Cushing's syndrome is the most frequent endocrine lesion in CNC. The complex has been mapped to 2p16 and 17q22-24, although additional heterogeneity may exist. The gene coding for the protein kinase A (PKA) type I-a regulatory subunit (RIa), PRKAR1A, had been mapped to 17q. Cloning of the PRKAR1A genomic structure and its sequencing showed mutations in CNC-, CNC with PPNAD- and sporadic PPNAD-patients. In CNC tumors, PKA activity showed increased stimulation by cAMP, whereas PKA activity ratio was decreased, and in CNC tumors, there is LOH of the normal allele, suggesting that normal PRKAR1A may be a tumor suppressor in these tissues. CNC is the first human disease caused by mutations of one of the subunits of the PKA enzyme, a critical component of the cAMP signaling system and a potential participant in many other signaling pathways.

NR0B1A: an alternatively spliced form of NR0B1

The orphan nuclear receptor DAX1 (dosage-sensitive sex reversal-AHC critical region on the X chromosome gene 1), encoded by the NR0B1 gene, plays important roles in the development of the hypothalamic-pituitary-adrenal/gonadal (HPAG) axis as well as in sex determination. Mutations in NR0B1 cause the X-linked cytomegalic form of adrenal hypoplasia congenita (AHC), and associated hypogonadotropic hypogonadism (HH). Over-expression of NR0B1 results in sex reversal in mice and duplication of the 160kb DSS locus in human patients results in a sex-reversed phenotype (XY females). The purpose of these investigations was to determine if alternatively spliced forms of NR0B1 existed. Analysis of expressed sequence tag data predicted a truncated isoform of DAX1. We confirmed the presence of an alternatively spliced form of NR0B1, which we will refer to as NR0B1A, by reverse transcriptase-polymerase chain reaction (RT-PCR), and will refer to the deduced protein isoform as DAX1A. Sequencing of the NR0B1A cDNA revealed slight differences from the recently described splice form, DAX1alpha. NR0B1A is encoded by NR0B1 exon 1 and exon 2A located within the 3385 nt intron between NR0B1 exons 1 and 2. Exon 2A includes 35 nt of coding sequence. NR0B1A encodes a deduced protein sequence, DAX1A, of 400 amino acids compared with 470 amino acids for DAX1. RT-PCR detected expression of NR0B1A in adrenal gland, testis, ovary, and pancreas. The identification of NR0B1A and the deduced DAX1A requires reinterpretation of many previous experiments involving expression and knockout of NR0B1 and DAX1.

[Clinical and molecular research in a case of familial Carney complex]

OBJECTIVE

A case of primary pigmented nodular adrenal disease (PPNAD) was first diagnosed in Ruijin Hospital, Shanghai, China and molecular genetic research was then carried on the proband and his family members.

METHODS

History and laboratory tests were routinely taken. Liddle's test, adrenal CT and pituitary magnetic resonance imaging were also carried out. Complete family history was obtained and eight of the family members donated their blood for DNA extraction. Polymerase chain reaction was done on all the exons of PRKAR1A gene and the product of the reaction was sequenced with ABI 3700. The right adrenal of the patient was then resected, part of the tissue was preserved in liquid nitrogen for DNA/RNA extraction and the remaining sent to Department of Pathology.

RESULTS

The patient presented an atypical appearance of Cushing's syndrome. His father had a typical history of cardiac myoma. Cortisone level could not be refrained in Liddle's test for the patient. Imaging examination presented a nodular adrenal and a full pituitary. A novel mutation of PRKAR1A-S147N was found in both the patient's and his father's gene.

CONCLUSIONS

This is the first patient diagnosed as PPNAD based on his clinical manifestations, laboratory tests and imaging and pathological examinations. According to the history of his father and the results of molecular genetic analysis, the diagnosis of Carney complex can be established on this patient and his father. It is also the first time that this kind of point mutation was found in Chinese people.

Allgrove or 4 "A" syndrome: an autosomal recessive syndrome causing multisystem neurological disease

Allgrove's or "4 A" syndrome is a rare autosomal recessive condition with alacrima, achalasia, autonomic disturbance, and ACTH insensitivity among other features. Recent studies have identified mutations in the AAAS, a candidate gene on chromosome 12q13 in such patients. Manifestations in adult patients are rarely reported. The syndrome usually presents during the first decade of life with dysphagia or severe (occasionally fatal) hypoglycaemic or hypotensive attacks, related to adrenocortical insufficiency. Onset of adrenal insufficiency or other features may be delayed to adulthood. In contrast with paediatric patients, adult patients with Allgrove's syndrome may present with multisystem neurological disease; the childhood history of achalasia or alacrima may be overlooked. The authors describe two families with two affected siblings and a further unrelated patient with typical clinical features of Allgrove's syndrome, who exhibit signs of multisystem neurological disease including hyperreflexia, muscle wasting, dysarthria, ataxia, optic atrophy, and intellectual impairment. None of the cases have developed adrenal insufficiency but all have progressive neurological disability. Autonomic dysfunction was a significant cause of morbidity in two cases. The three index cases represent the longest described follow up of Allgrove's syndrome into adulthood. It is speculated that they represent a subgroup of patients who follow an often undiagnosed chronic neurological course. Recognition of the syndrome presenting in adult life permits treatment of unrecognised autonomic dysfunction, adrenal insufficiency and dysphagia, and appropriate genetic advice.

SF-1, DAX-1, and acd: molecular determinants of adrenocortical growth and steroidogenesis

The formation of the adrenal cortex in humans is notable for the presence of two discrete zones, the fetal zone (FZ) which regresses soon after birth and the definitive zone (DZ) which gives rise to the classic steroidogenic zones of the adult cortex. Mice possess an analogous structure to the FZ referred to as the X-zone (XZ) which regresses at puberty in the male and during the first pregnancy in the female. Similar to the human FZ in X-linked Congenital Adrenal Hypoplasia caused by loss of function mutations in DAX-1 (Dosage-sensitive sex reversal-Adrenal hypoplasia congenita critical region on the X chromosome), the mouse XZ does not regress when DAX-1 is mutated. Only in humans with DAX-1 mutations, however, is the DZ small and hypofunctional. Patients and mice with SF-1 mutations have complete adrenal aplasia with absence of both the DZ and FZ/XZ. Lastly, the phenotype of the Autosomal Recessive Adrenocortical Dysplasia (acd) mouse is strikingly similar to human Miniature Adult Congenital Adrenal Hypoplasia, lacking an XZ/FZ and possessing a dysfunctional DZ. Current work has addressed the regulation of SF-1 and DAX-1 dependent adrenocortical growth and steroidogenesis in vivo utilizing mouse models of simple and combined SF-1 and DAX-1 deficiency. In addition, the model of compensatory adrenal growth in SF-1 haplo-insufficient mice has been applied to evaluate the potential role of SF-1 in adrenocortical proliferation. Additional efforts aim to positionally clone the acd gene, predicated on the hypothesis that it is a critical component of the adrenal developmental cascade.

Linkage of one gene for familial glucocorticoid deficiency type 2 (FGD2) to chromosome 8q and further evidence of heterogeneity

In several cases of familial glucocorticoid deficiency (FGD), referred to as FGD type 1, mutations have been described in the coding exon of the adrenocorticotropin receptor (melanonocortin receptor type 2, MC2R) gene. However, for the majority of cases (FGD type 2), no mutations were found in this gene. In the more informative families, the involvement of the MC2R locus could be excluded by linkage or sequencing analysis and, as there was no obvious candidate gene, a genome linkage scan was performed. Fourteen families were studied in this report. Evidence of linkage was found with markers on chromosome 8q in three out of the 14 families (maximum heterogeneity LOD score of 2.81 at D8S1763). These three families were consanguineous and the gene could be located by homozygosity mapping between markers D8S285 and D8S1718 in a 8.8-cM region. No potential candidate genes were apparent in the region. Linkage to this region could be excluded in some families from our sample giving highly negative LOD scores with the markers of the region. This result suggests that at least one other gene, located on a different region, must be responsible for FGD in these families and provides new evidence of genetic heterogeneity of this disorder.

New genetic insights in familial hyperaldosteronism

Aldosterone, the major circulating mineralocorticoid, particiates in blood volume and serum potassium homeostasis. Primary aldosteronism is a disorder characterized by hypertension and, in more severe form, hypokalemia, due to autonomous aldosterone secretion from the adrenocortical zona glomerulosa. Improved screening techniques, particularly application of the plasma aldosterone: plasma renin activity ratio, has led to renewed interest in Conn's original proposal that primary aldosteronism may be the cause of increased blood pressure in about 10% of adults with hypertension. Glucocorticoid-remediable aldosteronism (GRA) was the first described familial form of hyperaldosteronism. The disorder is characterized by aldosterone secretory function regulated chronically by ACTH. Hence, aldosterone hypersecretion can be chronically suppressed by exogenous glucocorticoids such as dexamethasone in physiologic-range doses. This autosomal dominant disorder has been shown to be caused by a hybrid gene mutation formed by a cross-over of genetic material between the ACTH-responsive regulatory portion of the 11b-hydroxylase (CYP11B1) gene and the coding region of the aldosterone synthase (CYP11B2) gene. Familial hyperaldosteronism type II (FH-II), so named to distinguish the disorder from GRA or familial hyperaldosteronism type I (FH-I), is characterized by inheritance consistent with an autosomal dominant pattern of autonomous aldosterone hypersecretion which is not suppressible by dexamethasone. Linkage analysis in a single large kindred, and direct mutation screening, has shown that this disorder is unrelated to mutations in the genes for aldosterone synthase or the angiotensin II receptor. A recent genome-wide search has identified a genetic linkage between FH-II in this single large kindred and polymorphic gene markers on chromosome 7 in a region that corresponds to cytogenetic band 7p22. This is the first identified locus for FH-II. Several possible candidate genes have been localized to the 7p22 region. The precise genetic cause of FH-II remains to be elucidated.

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.

Contribution of the microvessel network to the clonal and kinetic profiles of adrenal cortical proliferative lesions

Monoclonal adrenocortical lesions have been characterized by an inverse correlation between proliferation and apoptosis, and polyclonal lesions show a direct correlation. Their relationship with the vascular pattern remains unknown in adrenocortical nodular hyperplasias (ACNHs), adenomas (ACAs), and carcinomas (ACCs). We studied 20 ACNHs, 25 ACAs, and 10 ACCs (World Health Organization classification criteria) from 55 women. The analysis included X-chromosome inactivation assay (on microdissected samples), slide and flow cytometry, and in situ end labeling. Endothelial cells were stained with anti-CD31, and the blood vessel area and density were quantified by image analysis in the same areas. Appropriate tissue controls were run in every case. Regression analyses between kinetic and vascular features were performed in both polyclonal and monoclonal lesions. Polyclonal patterns were observed in 14 of 18 informative ACNHs and 3 of 22 informative ACAs, and monoclonal patterns were seen in 4 of 18 ACNHs, 19 of 22 ACAs, and 9 of 9 ACCs. A progressive increase in microvessel area was observed in the ACNH-ACA-ACC transition but was statistically significant between benign and malignant lesions only (191.36 +/- 168.32 v 958.07 +/- 1279.86 microm(2); P < .0001). In addition, case stratification by clonal pattern showed significant differences between polyclonal and monoclonal benign lesions; 6% of polyclonal and 57% of monoclonal lesions had microvessel area >186 microm(2) (P = .0000008). Monoclonal lesions showed parallel trends (but with opposite signs) for microvessel area and density in comparison with proliferation and apoptosis, whereas polyclonal lesions showed inverse trends. In conclusion, the kinetic advantage of monoclonal adrenal cortical lesions (increased proliferation, decreased apoptosis) is maintained by parallel increases in microvessel area and density.

Genetics of adrenocortical tumors: Carney complex

Adrenal cancer is a rare neoplasm; however, up to 1 in 1 500 adrenal incidentalomas may hide a carcinoma, which, if diagnosed late or left untreated, is associated with significant morbidity and mortality. Despite extensive investigation of the molecular mechanisms involved in adrenal carcinogenesis and significant improvements in diagnostic imaging, efforts to cure advanced adrenal cancer remain largely unsuccessful. Thus, the investigation of the genetics of adrenocortical cancer by the candidate or positional cloning gene approach is essential in the development of new therapies for this disease. We propose that adrenocortical tumorigenesis follows a pattern similar to that in other organs: As the pathology of the adrenocortical tumor increases towards malignancy, the genetic changes that are observed also increase. Known genetic associations, like TP53 gene changes, occur during the latest stages of adrenocortical tumorigenesis. Thus, it is essential to study the relatively few genes that are affected at the beginning of this process, at the stages of benign tumorigenesis in the cortex. We have studied primary pigmented adrenocortical disease (PPNAD), a benign, bilateral, adrenocortical hyperplasia, which either in its isolated form or as part of Carney complex (CNC), is inherited in an autosomal dominant manner and, therefore, the gene(s) responsible for this disorder could be identified by positional cloning approaches. Indeed, we have identified two genetic loci harboring genes for PPNAD and/or CNC on chromosomal loci 2p16 and 17q22-24. The chromosome 17 gene, PRKAR1A, was recently cloned and the identification of other responsible genes is currently under way in our, and collaborating laboratories. The present report reviews the genetics of adrenocortical cancer first, followed by what is known today about the genetics of PPNAD and/or CNC.

Novel human corticosteroid-binding globulin variant with low cortisol-binding affinity

Corticosteroid-binding globulin (CBG) is the plasma transport protein that regulates the access of glucocorticoid hormones to target cells. Genetic deficiencies of CBG are rare, and only a single human CBG variant (Trancortin Leuven) has been related so far to decreased cortisol-binding affinity. We report here on a 43-yr-old woman, referred for chronic asthenia and hypotension, with repeatedly low morning serum cortisol levels (22-61 nmol/L; normal range, 204-546 nmol/L), normal plasma ACTH levels (38-49 pg/mL; normal, <50 pg/mL), and normal urinary cortisol (10-76 nmol/24 h; normal range, 10-105 nmol/24 h). An increased percent-free (dialysable fraction) serum cortisol (8.7-9.7%, normal range, 2.9-3.9%) suggested abnormal CBG binding activity. Indeed, she had a low serum CBG concentration (24 mg/L vs. 44+/-6 mg/L in normal women), and the affinity of her CBG for cortisol was decreased (association constant, Ka = 0.12 L/nmol vs. 0.82+/-0.29 L/nmol). In her immediate family members, the serum CBG concentration and cortisol-binding activity were normal in her husband, but the four living children had slightly lower serum CBG concentrations than the reference ranges for their pre- and postpubertal status. Measurements of cortisol distribution in undiluted serum indicated that an increase in the percentage of nonprotein-bound cortisol offsets the low cortisol levels to give approximately normal concentrations of free cortisol in serum. Direct sequencing of PCR-amplified exons encoding CBG revealed that the proband was homozygous for a polymorphism (GAC-AAC) in the codon for residue 367, which results in a Asp367-->Asn substitution. Her children were heterozygous for this polymorphism. When this nucleotide change was introduced into a normal human CBG complementary DNA, for expression in Chinese hamster ovary cells, Scatchard analysis demonstrated that the Asn367 substitution reduced the affinity of human CBG for cortisol by approximately 4-fold (Ka = 0.15 L/nmol), as compared to normal recombinant CBG (Ka = 0.66 L/nmol). These results suggest that Asp367 is an important determinant of CBG steroid-binding activity and that normal negative regulation of the hypothalamic-pituitary-adrenal axis is maintained by relatively normal serum-free cortisol concentrations, despite a marked reduction in the steroid-binding affinity of this novel human CBG variant, which we have designated as CBG-Lyon.