Large deletions of the PRKAR1A gene in Carney complex

Carney complex: A clinicopathologic study on a single family from several Canadian provinces

Carney syndrome is an autosomal dominant complex involving endocrinopathy, mucocutaneous hyperpigmentation, and different tumors, including cardiac myxomas. We report on a single family with several members affected with Carney syndrome. Family and individual medical histories were investigated in several Canadian provinces. The histology slides were also reviewed. Four family members (two young women, both sisters, their mother, and maternal grandmother) were found to harbor Carney syndrome. Everyone was presented with multiple and recurrent atrial myxomas of the heart, requiring multiple open cardiac surgeries. Breast myxomas and cutaneous hyperpigmentation were also revealed in one of the sisters and their mother. Interestingly, genetic testing was positive for the female family members and negative for the father and brother. We cannot rule out that the brother may have had a new mutation or harboring a mosaic. The young woman's brother did not have cardiac myxoma but developed a unilateral Sertoli cell tumor of testis. Carney syndrome is a rare complex multisystemic genetic disorder, including multiple and recurrent cardiac myxomas. We strongly suggest that reporting familial Carney syndrome is still critical in the 21st century to augment the awareness of this situation among clinicians and pathologists.

Consensus statement by the French Society of Endocrinology (SFE) and French Society of Pediatric Endocrinology & Diabetology (SFEDP) for the diagnosis of Cushing's syndrome: Genetics of Cushing's syndrome

Cushing's syndrome is due to overproduction of cortisol, leading to abnormal and prolonged exposure to cortisol. The most common etiology is Cushing disease, while adrenal causes are rarer. Knowledge of the genetics of Cushing's syndrome, and particularly the adrenal causes, has improved considerably over the last 10 years, thanks in particular to technical advances in high-throughput sequencing. The present study, by a group of experts from the French Society of Endocrinology and the French Society of Pediatric Endocrinology and Diabetology, reviewed the literature on germline genetic alterations leading to a predisposition to develop Cushing's syndrome. The review led to a consensus statement on genetic screening for Cushing disease and adrenal Cushing's syndrome.

Whole genome sequencing resolves 10 years diagnostic odyssey in familiar myxoma

Carney complex (CNC) is an ultrarare disorder causing cutaneous and cardiac myxomas, primary pigmented nodular adrenocortical disease, hypophyseal adenoma, and gonadal tumours. Genetic alterations are often missed under routine genetic testing. Pathogenic variants in PRKAR1A are identified in most cases, while large exonic or chromosomal deletions have only been reported in a few cases. Our aim was to identify the causal genetic alteration in our kindred with a clinical diagnosis of CNC and prove its pathogenic role by functional investigation. Targeted testing of PRKAR1A gene, whole exome and whole genome sequencing (WGS) were performed in the proband, one clinically affected and one unaffected relative. WGS identified a novel, large, 10,662 bp (10.6 kbp; LRG_514t1:c.-10403_-7 + 265del; hg19, chr17:g.66498293_66508954del) deletion in the promoter of PRKAR1A in heterozygous form in the affected family members. The exact breakpoints and the increased enzyme activity in deletion carriers compared to wild type carrier were proved. Segregation analysis and functional evaluation of PKA activity confirmed the pathogenic role of this alteration. A novel deletion upstream of the PRKAR1A gene was proved to be the cause of CNC. Our study underlines the need for WGS in molecular genetic testing of patients with monogenic disorders where conventional genetic analysis fails.

Malignant Melanotic Nerve Sheath Tumors: A Review of Clinicopathologic and Molecular Characteristics

Malignant melanotic nerve sheath tumor (MMNST) which was formerly known as melanocytic schwannoma, is an uncommon aggressive type of nerve sheath tumor. It originates from nerve roots with clonal Schwann cell proliferation and melanin pigment production. MMNST which was once thought to be a benign tumor is now considered a malignant disease based on the latest 2020 World Health Organization classification of soft tissue tumors. Interestingly, despite the histologic features appearing benign with a low proliferation index, the clinical course of this tumor is malignant, which was demonstrated in case series with high rate of recurrences and metastasis. This tumor can occur sporadically or in patients with an underlying familial predisposition syndrome called, Carney's complex. Affected patients will often harbor a germline mutation in the PRKAR1A gene. MMNST can be histologically difficult to distinguish from malignant melanoma, other melanocytic tumors, and Schwannoma. Having a better understanding of its clinic pathologic characteristics and associated conditions is essential in properly diagnosing and managing affected individuals. This includes the possible need for genetic testing to detect germline mutations, genetic counseling, and surveillance according to published recommendations. In this article, we summarize the clinic pathologic and molecular features of MMNST and discuss what is known about its molecular biology and its associations with predisposing conditions. The review was conducted through an extensive PubMed search using keywords then relevant publications were selected.

A novel 8.57-kb deletion of the upstream region of PRKAR1A in a family with Carney complex

Carney complex (CNC) is a rare hereditary syndrome that involves endocrine dysfunction and the development of various types of tumors. Chromosome 2p16 and PRKAR1A on chromosome 17 are known susceptibility loci for CNC. Here we report a mother and son with CNC caused by an 8.57‐kb deletion involving the transcription start site and non‐coding exon 1 of PRKAR1A. The proband is a 28‐year‐old male with bilateral large‐cell calcified Sertoli cell testicular tumors and pituitary adenoma. Comprehensive genomic profiling for cancer mutations using Foundation One CDx failed to detect any mutations in PRKAR1A in DNA from the testicular tumor. Single‐nucleotide polymorphism array analysis of the proband’s genomic DNA revealed a large deletion in the 5′ region of PRKAR1A. Genomic walking further delineated the region an 8.57‐kb deletion. A 1.68‐kb DNA fragment encompassed by the deleted region showed strong promoter activity in a NanoLuc luciferase reporter assay. The patient’s mother, who is suffering from recurrent cardiac myxoma, a critical sign for CNC, carried an identical deletion. The 8.57‐kb deleted region is a novel lesion for CNC and will facilitate molecular diagnosis of the disease.

Disorders of the adrenal cortex: Genetic and molecular aspects

Adrenal cortex produces glucocorticoids, mineralocorticoids and adrenal androgens which are essential for life, supporting balance, immune response and sexual maturation. Adrenocortical tumors and hyperplasias are a heterogenous group of adrenal disorders and they can be either sporadic or familial. Adrenocortical cancer is a rare and aggressive malignancy, and it is associated with poor prognosis. With the advance of next-generation sequencing technologies and improvement of genomic data analysis over the past decade, various genetic defects, either from germline or somatic origin, have been unraveled, improving diagnosis and treatment of numerous genetic disorders, including adrenocortical diseases. This review gives an overview of disorders associated with the adrenal cortex, the genetic factors of these disorders and their molecular implications.

Bilateral Adrenal Hyperplasia: Pathogenesis and Treatment

Bilateral adrenal hyperplasia is a rare cause of Cushing’s syndrome. Micronodular adrenal hyperplasia, including the primary pigmented micronodular adrenal dysplasia (PPNAD) and the isolated micronodular adrenal hyperplasia (iMAD), can be distinguished from the primary bilateral macronodular adrenal hyperplasia (PBMAH) according to the size of the nodules. They both lead to overt or subclinical CS. In the latter case, PPNAD is usually diagnosed after a systematic screening in patients presenting with Carney complex, while for PBMAH, the diagnosis is often incidental on imaging. Identification of causal genes and genetic counseling also help in the diagnoses. This review discusses the last decades’ findings on genetic and molecular causes of bilateral adrenal hyperplasia, including the several mechanisms altering the PKA pathway, the recent discovery of ARMC5, and the role of the adrenal paracrine regulation. Finally, the treatment of bilateral adrenal hyperplasia will be discussed, focusing on current data on unilateral adrenalectomy.

Gαs-Protein Kinase A (PKA) Pathway Signalopathies: The Emerging Genetic Landscape and Therapeutic Potential of Human Diseases Driven by Aberrant Gαs-PKA Signaling

Many of the fundamental concepts of signal transduction and kinase activity are attributed to the discovery and crystallization of cAMP-dependent protein kinase, or protein kinase A. PKA is one of the best-studied kinases in human biology, with emphasis in biochemistry and biophysics, all the way to metabolism, hormone action, and gene expression regulation. It is surprising, however, that our understanding of PKA's role in disease is largely underappreciated. Although genetic mutations in the PKA holoenzyme are known to cause diseases such as Carney complex, Cushing syndrome, and acrodysostosis, the story largely stops there. With the recent explosion of genomic medicine, we can finally appreciate the broader role of the Gαs-PKA pathway in disease, with contributions from aberrant functioning G proteins and G protein-coupled receptors, as well as multiple alterations in other pathway components and negative regulators. Together, these represent a broad family of diseases we term the Gαs-PKA pathway signalopathies. The Gαs-PKA pathway signalopathies encompass diseases caused by germline, postzygotic, and somatic mutations in the Gαs-PKA pathway, with largely endocrine and neoplastic phenotypes. Here, we present a signaling-centric review of Gαs-PKA-driven pathophysiology and integrate computational and structural analysis to identify mutational themes commonly exploited by the Gαs-PKA pathway signalopathies. Major mutational themes include hotspot activating mutations in Gαs, encoded by GNAS, and mutations that destabilize the PKA holoenzyme. With this review, we hope to incite further study and ultimately the development of new therapeutic strategies in the treatment of a wide range of human diseases. SIGNIFICANCE STATEMENT: Little recognition is given to the causative role of Gαs-PKA pathway dysregulation in disease, with effects ranging from infectious disease, endocrine syndromes, and many cancers, yet these disparate diseases can all be understood by common genetic themes and biochemical signaling connections. By highlighting these common pathogenic mechanisms and bridging multiple disciplines, important progress can be made toward therapeutic advances in treating Gαs-PKA pathway-driven disease.

Can Discord Domain-Containing Receptor 2 Mutation Act as a Disease Modifier for PRKAR1A Associated Melanotic Schwannoma?

Melanotic Schwannomas are rare neural sheath tumors with distinctive findings of both Schwann cells and melanocytic cells. Recognition of this entity has prompted the importance of distinction from similar tumor types such as melanomas. Early diagnosis facilitates removal of the mass with less risk of local invasion and metastasis. Although previously known as mostly benign lesions, malignant conversion and recurrence are recognized. This paper presents a patient with melanotic schwannoma, describes the distinctive features that will separate it from melanoma, and addresses the possibility of further guided therapy through next-generation sequencing.

Diagnostic Pathology of Tumors of Peripheral Nerve

Neoplasms of the peripheral nervous system represent a heterogenous group with a wide spectrum of morphological features and biological potential. They range from benign and curable by complete excision (schwannoma and soft tissue perineurioma) to benign but potentially aggressive at the local level (plexiform neurofibroma) to the highly malignant (malignant peripheral nerve sheath tumors [MPNST]). In this review, we discuss the diagnostic and pathologic features of common peripheral nerve sheath tumors, particularly those that may be encountered in the intracranial compartment or in the spine and paraspinal region. The discussion will cover schwannoma, neurofibroma, atypical neurofibromatous neoplasms of uncertain biological potential, intraneural and soft tissue perineurioma, hybrid nerve sheath tumors, MPNST, and the recently renamed enigmatic tumor, malignant melanotic nerve sheath tumor, formerly referred to as melanotic schwannoma. We also discuss the diagnostic relevance of these neoplasms to specific genetic and familial syndromes of nerve, including neurofibromatosis 1, neurofibromatosis 2, and schwannomatosis. In addition, we discuss updates in our understanding of the molecular alterations that represent key drivers of these neoplasms, including neurofibromatosis type 1 and type 2, SMARCB1, LZTR1, and PRKAR1A loss, as well as the acquisition of CDKN2A/B mutations and alterations in the polycomb repressor complex members (SUZ12 and EED) in the malignant progression to MPNST. In summary, this review covers practical aspects of pathologic diagnosis with updates relevant to neurosurgical practice.

First Somatic PRKAR1A Defect Associated With Mosaicism for Another PRKAR1A Mutation in a Patient With Cushing Syndrome

Context

Primary pigmented nodular adrenocortical disease (PPNAD) is a rare cause of ACTH-independent Cushing syndrome (CS) associated mostly with Carney complex (CNC), a rare autosomal dominant multiple neoplasia syndrome. More than two-thirds of familial cases and approximately one-third of sporadic cases of CNC harbor germline inactivating PRKAR1A defects. Increasingly sensitive technologies for the detection of genetic defects such as next-generation sequencing (NGS) have further highlighted the importance of mosaicism in human disease.

Case Description

A 33-year-old woman was diagnosed with ACTH-independent CS with abdominal computed tomography showing bilateral micronodular adrenal hyperplasia with a left adrenal adenoma. She underwent left adrenalectomy with pathology demonstrating PPNAD with a 1.5-cm pigmented adenoma. DNA analysis by Sanger sequencing revealed 2 different PRKAR1A variants in the adenoma that were absent from DNA extracted from blood and saliva: c.682C > T and c.974-2A > G. "Deep" NGS revealed that 0.31% of DNA copies extracted from blood and saliva did in fact carry the c.682C > T variant, suggesting low-level mosaicism for this defect.

Conclusions

We present a case of PPNAD due to low-level mosaicism for a PRKAR1A defect which led to the formation of an adenoma due to a second, adrenal-specific, somatic PRKAR1A mutation. The identification of mosaicism for PRKAR1A, depending on the number and distribution of cells affected has implications for genetic counseling and tumor surveillance. This is the first recorded case of a patient with PRKAR1A mosaicism, PPNAD, and an adenoma forming due to complete inactivation of PRKAR1A in adrenal tissue from a second, somatic-only, PRKAR1A coding sequence mutation.

Genetics of Pituitary Tumours

Pituitary tumours are relatively common in the general population. Most often they occur sporadically, with somatic mutations accounting for a significant minority of somatotroph and corticotroph adenomas. Pituitary tumours can also develop secondary to germline mutations as part of a complex syndrome or as familial isolated pituitary adenomas. Tumours occurring in a familial setting may present at a younger age and can behave more aggressively with resistance to treatment. This chapter will focus on the genetics and molecular pathogenesis of pituitary tumours.

Acromegaly in Carney complex

PURPOSE

Carney complex (CNC) is a rare autosomal dominant syndrome, characterized by mucocutaneous pigmentation, cardiac, cutaneous myxomas and endocrine overactivity. It is generally caused by inactivating mutations in the PRKAR1A (protein kinase cAMP-dependent type I regulatory subunit alpha) gene. Acromegaly is an infrequent manifestation of CNC, reportedly diagnosed in 10% of patients.

METHODS

We here report the case of a patient who was concomitantly diagnosed with Carney complex, due to a new mutation in PRKAR1A ((NM_002734.3:c.80_83del, p.(Ile27Lysfs*101 in exon 2), and acromegaly. In parallel, we conducted an extensive review of published case reports of acromegaly in the setting of CNC.

RESULTS

The 43-year-old patient was diagnosed with an acromegaly due to a GH-secreting pituitary microadenoma resistant to somatostatin analogs. He underwent transsphenoidal surgery in our tertiary referral center, which found a pure GH-secreting adenoma. In the literature, we identified 57 cases (24 men, 33 women) of acromegaly in CNC patients. The median age at diagnosis was 28.8 ± 12 year and there were 6 cases of gigantism. Acromegaly revealed CNC in only 4 patients. 24 patients had a microadenoma and two carried pituitary hyperplasia and/or multiple adenomas, suggesting that CNC may result in a higher proportion of microadenoma as compared to non-CNC acromegaly.

CONCLUSIONS

Although it rarely reveals CNC, acromegaly is diagnosed at a younger age in this setting, with a higher proportion of microadenomas.

Germline and mosaic mutations causing pituitary tumours: genetic and molecular aspects

While 95% of pituitary adenomas arise sporadically without a known inheritable predisposing mutation, in about 5% of the cases they can arise in a familial setting, either isolated (familial isolated pituitary adenoma or FIPA) or as part of a syndrome. FIPA is caused, in 15-30% of all kindreds, by inactivating mutations in the AIP gene, encoding a co-chaperone with a vast array of interacting partners and causing most commonly growth hormone excess. While the mechanisms linking AIP with pituitary tumorigenesis have not been fully understood, they are likely to involve several pathways, including the cAMP-dependent protein kinase A pathway via defective G inhibitory protein signalling or altered interaction with phosphodiesterases. The cAMP pathway is also affected by other conditions predisposing to pituitary tumours, including X-linked acrogigantism caused by duplications of the GPR101 gene, encoding an orphan G stimulatory protein-coupled receptor. Activating mosaic mutations in the GNAS gene, coding for the Gα stimulatory protein, cause McCune-Albright syndrome, while inactivating mutations in the regulatory type 1α subunit of protein kinase A represent the most frequent genetic cause of Carney complex, a syndromic condition with multi-organ manifestations also involving the pituitary gland. In this review, we discuss the genetic and molecular aspects of isolated and syndromic familial pituitary adenomas due to germline or mosaic mutations, including those secondary to AIP and GPR101 mutations, multiple endocrine neoplasia type 1 and 4, Carney complex, McCune-Albright syndrome, DICER1 syndrome and mutations in the SDHx genes underlying the association of familial paragangliomas and phaeochromocytomas with pituitary adenomas.

Genetics of micronodular adrenal hyperplasia and Carney complex

Micronodular bilateral adrenal hyperplasia (MiBAH) is a rare cause of adrenal Cushing syndrome (CS). The investigations carried out on this disorder during the last two decades suggested that it could be divided into at least two entities: primary pigmented nodular adrenocortical disease (PPNAD) and isolated micronodular adrenocortical disease (i-MAD). The most common presentation of MiBAH is familial PPNAD as part of Carney complex (CNC) (cPPNAD). CNC, associated with multiple endocrine and non-endocrine neoplasias, was first described in 1985 in 40 patients, 10 of whom were familial cases. In 2000, we identified inactivating germline mutations of the PRKAR1A gene, encoding the regulatory subunit type 1α (RIα) of protein kinase A (PKA), in the majority of patients with CNC and PPNAD. PRKAR1A mutations causing CNC lead to increased PKA activity. Since then, additional genetic alterations in the cAMP/PKA signaling pathway leading to increased PKA activity have been described in association with MiBAH. This review summarizes older and recent findings on the genetics and pathophysiology of MiBAH, PPNAD, and related disorders.

Anxiety-like behavior and other consequences of early life stress in mice with increased protein kinase A activity

Anxiety disorders are associated with abnormalities in fear-learning and bias to threat; early life experiences are influential to the development of an anxiety-like phenotype in adulthood. We recently reported that adult mice (Prkar1a+/-) with haploinsufficiency for the main regulatory subunit of the protein kinase A (PKA) exhibit an anxiety-like phenotype associated with increased PKA activity in the amygdala. PKA is the main effector of cyclic adenosine mono-phosphate signaling, a key pathway involved in the regulation of fear learning. Since anxiety has developmental and genetic components, we sought to examine the interaction of a genetic defect associated with anxiety phenotype and early life experiences. We investigated the effects of neonatal maternal separation or tactile stimulation on measures of behavior typical to adolescence as well as developmental changes in the behavioral phenotype between adolescent and adult wild-type (WT) and Prkar1a+/- mice. Our results showed developmental differences in assays of anxiety and novelty behavior for both genotypes. Adolescent mice showed increased exploratory and novelty seeking behavior compared to adult counterparts. However, early life experiences modulated behavior in adolescent WT differently than in adolescent Prkar1a+/- mice. Adolescent WT mice exposed to early life tactile stimulation showed attenuation of anxiety-like behavior, whereas an increase in exploratory behavior was found in Prkar1a+/- adolescent mice. The finding of behavioral differences that are apparent during adolescence in Prkar1a^+/- mice suggests that long-term exposure of the brain to increased PKA activity during critical developmental periods contributes to the anxiety-like phenotype noted in the adult animals with increased PKA activity.

Diagnosis and management of pseudohypoparathyroidism and related disorders: first international Consensus Statement

This Consensus Statement covers recommendations for the diagnosis and management of patients with pseudohypoparathyroidism (PHP) and related disorders, which comprise metabolic disorders characterized by physical findings that variably include short bones, short stature, a stocky build, early-onset obesity and ectopic ossifications, as well as endocrine defects that often include resistance to parathyroid hormone (PTH) and TSH. The presentation and severity of PHP and its related disorders vary between affected individuals with considerable clinical and molecular overlap between the different types. A specific diagnosis is often delayed owing to lack of recognition of the syndrome and associated features. The participants in this Consensus Statement agreed that the diagnosis of PHP should be based on major criteria, including resistance to PTH, ectopic ossifications, brachydactyly and early-onset obesity. The clinical and laboratory diagnosis should be confirmed by a molecular genetic analysis. Patients should be screened at diagnosis and during follow-up for specific features, such as PTH resistance, TSH resistance, growth hormone deficiency, hypogonadism, skeletal deformities, oral health, weight gain, glucose intolerance or type 2 diabetes mellitus, and hypertension, as well as subcutaneous and/or deeper ectopic ossifications and neurocognitive impairment. Overall, a coordinated and multidisciplinary approach from infancy through adulthood, including a transition programme, should help us to improve the care of patients affected by these disorders.

Carney complex with PRKAR1A gene mutation: A case report and literature review

RATIONALE

Carney complex (CNC) is a multiple neoplasia syndrome with autosomal dominant inheritance. CNC is characterized by the presence of myxomas, spotty skin pigmentation, and endocrine overactivity. No direct correlation has been established between disease-causing mutations and phenotype.

PATIENT CONCERNS

A 16-year-old boy was admitted because of excessive weight gain over 3 years and purple striae for 1 year. Physical examination revealed Cushingoid features and spotty skin pigmentation on his face, lip, and sclera.

DIAGNOSES

The patient was diagnosed as Carney complex.

INTERVENTIONS

the patient underwent right adrenalectomy and partial adrenalectomy of the left adrenal gland.

OUTCOME

Results of imaging showed bilateral adrenal nodular hyperplasia, multiple microcalcifications of the bilateral testes, and compression fracture of the thoracolumbar spine. Histopathological results confirmed multiple pigmented nodules in the adrenal glands. DNA sequencing revealed a nonsense mutation in the gene encoding regulatory subunit type 1-alpha of protein kinase A (PRKAR1A; c.205C > T). After the second adrenalectomy, the Cushingoid features disappeared, and cortisol levels returned to normal.

LESSONS

Carney complex is a rare disease that lacks consistent genotype-phenotype correlations. Our patient, who carried a germline PRKAR1A nonsense mutation (c.205C > T), clinical features included spotty skin pigmentation, osteoporosis, and primary pigmented nodular adrenal disease. Adrenalectomy is the preferred treatment for Cushing syndrome due to primary pigmented nodular adrenal disease.

Harvey Cushing Treated the First Known Patient With Carney Complex

Context:

Carney complex (CNC) is a syndrome characterized by hyperplasia of endocrine organs and may present with clinical features of Cushing syndrome and acromegaly due to functional adrenal and pituitary gland tumors. CNC has been linked to mutations in the regulatory subunit of protein kinase A type I-alpha (PRKAR1A) gene.

Design:

Tissue samples were taken from the hypothalamus or thalamus or tumors of patients with pituitary adenomas seen and operated on by neurosurgeon Harvey Cushing between 1913 and 1932. Following DNA extraction, sequencing for genes of interest was attempted, including PRKAR1A, AIP, USP8, GNAS1, and GPR101, to explore the possibility that these mutations associated with acromegaly, CNC, and Cushing syndrome have been conserved over time.

Results:

We report a patient described by Dr. Cushing in 1914 with a clinical presentation and postmortem findings suggestive of CNC. Genetic sequencing of the hypothalamus and pituitary adenoma revealed a germline heterozygous p.Arg74His mutation in the PRKAR1A gene, a codon previously described as mutated in CNC, but with a novel amino acid change.

Conclusions:

This patient is, to our knowledge, the first molecularly confirmed individual with CNC. This case demonstrates the power of modern genetics in studying archived tissues and the importance of recording detailed clinical notes in the diagnosis of disease.

Genetic Aspects of Pituitary Adenomas

Although most of pituitary adenomas are benign, they may cause significant burden to patients. Sporadic adenomas represent the vast majority of the cases, where recognized somatic mutations (eg, GNAS or USP8), as well as altered gene-expression profile often affecting cell cycle proteins have been identified. More rarely, germline mutations predisposing to pituitary adenomas -as part of a syndrome (eg, MEN1 or Carney complex), or isolated to the pituitary (AIP or GPR101) can be identified. These alterations influence the biological behavior, clinical presentations and therapeutic responses, and their full understanding helps to provide appropriate care for these patients.

Germline variants in familial pituitary tumour syndrome genes are common in young patients and families with additional endocrine tumours

OBJECTIVE

Familial pituitary tumour syndromes (FPTS) account for 5% of pituitary adenomas. Multi-gene analysis via next-generation sequencing (NGS) may unveil greater prevalence and inform clinical care. We aimed to identify germline variants in selected patients with pituitary adenomas using a targeted NGS panel.

DESIGN

We undertook a nationwide cross-sectional study of patients with pituitary adenomas with onset ≤40 years of age and/or other personal/family history of endocrine neoplasia. A custom NGS panel was performed on germline DNA to interrogate eight FPTS genes. Genome data were analysed via a custom bioinformatic pipeline, and validation was performed by Sanger sequencing. Multiplex ligation-dependent probe amplification (MLPA) was performed in cases with heightened suspicion for MEN1, CDKN1B and AIP mutations. The main outcomes were frequency and pathogenicity of rare variants in AIP, CDKN1B, MEN1, PRKAR1A, SDHA, SDHB, SDHC and SDHD.

RESULTS

Forty-four patients with pituitary tumours, 14 of whom had a personal history of other endocrine tumours and/or a family history of pituitary or other endocrine tumours, were referred from endocrine tertiary-referral centres across Australia. Eleven patients (25%) had a rare variant across the eight FPTS genes tested: AIP (p.A299V, p.R106C, p.F269F, p.R304X, p.K156K, p.R271W), MEN1 (p.R176Q), SDHB (p.A2V, p.S8S), SDHC (p.E110Q) and SDHD (p.G12S), with two patients harbouring dual variants. Variants were classified as pathogenic or of uncertain significance in 9/44 patients (20%). No deletions/duplications were identified in MEN1, CDKN1B or AIP.

CONCLUSIONS

A high yield of rare variants in genes implicated in FPTS can be found in selected patients using an NGS panel. It may also identify individuals harbouring more than one rare variant.

Sporadic pituitary adenomas: the role of germline mutations and recommendations for genetic screening

Although most pituitary adenomas occur sporadically, these common tumors can present in a familial setting in approximately 5% of cases. Germline mutations in several genes with autosomal dominant (AIP, MEN1, CDKN1B, PRKAR1A, SDHx) or X-linked dominant (GPR101) inheritance are causative of familial pituitary adenomas. Due to variable disease penetrance and occurrence of de novo mutations, some patients harboring germline mutations have no family history of pituitary adenomas (simplex cases). Areas covered: We summarize the recent findings on the role of germline mutations associated with familial pituitary adenomas in patients with sporadic clinical presentation. Expert commentary: Up to 12% of patients with young onset pituitary adenomas (age at diagnosis/onset ≤30 years) and up to 25% of simplex patients with gigantism carry mutations in the AIP gene, while most cases of X-linked acrogigantism (XLAG) due to GPR101 duplication are simplex female patients with very early disease onset (<5 years). With regard to the syndromes of multiple endocrine neoplasia (MEN), MEN1 mutations can be identified in a significant proportion of patients with childhood onset prolactinomas. Somatotroph and lactotroph adenomas are the most common pituitary adenomas associated with germline predisposing mutations. Genetic screening should be considered in patients with young onset pituitary adenomas.

Pitfalls and uncertain prognosis in pathological diagnosis of psammomatous melanotic schwannoma

A 20-year-old woman presenting with a pelvic mass identified as a psammomatous melanotic schwannoma (PMS) with atypical histological features was later found to have family history of cardiac myxomas consistent with Carney's complex. The BRAF V600E mutation was absent in the tumor.

MEN1, MEN4, and Carney Complex: Pathology and Molecular Genetics

Pituitary adenomas are a common feature of a subset of endocrine neoplasia syndromes, which have otherwise highly variable disease manifestations. We provide here a review of the clinical features and human molecular genetics of multiple endocrine neoplasia (MEN) type 1 and 4 (MEN1 and MEN4, respectively) and Carney complex (CNC). MEN1, MEN4, and CNC are hereditary autosomal dominant syndromes that can present with pituitary adenomas. MEN1 is caused by inactivating mutations in the MEN1 gene, whose product menin is involved in multiple intracellular pathways contributing to transcriptional control and cell proliferation. MEN1 clinical features include primary hyperparathyroidism, pancreatic neuroendocrine tumours and prolactinomas as well as other pituitary adenomas. A subset of patients with pituitary adenomas and other MEN1 features have mutations in the CDKN1B gene; their disease has been called MEN4. Inactivating mutations in the type 1α regulatory subunit of protein kinase A (PKA; the PRKAR1A gene), that lead to dysregulation and activation of the PKA pathway, are the main genetic cause of CNC, which is clinically characterised by primary pigmented nodular adrenocortical disease, spotty skin pigmentation (lentigines), cardiac and other myxomas and acromegaly due to somatotropinomas or somatotrope hyperplasia.

5th International ACC Symposium: The New Genetics of Benign Adrenocortical Neoplasia: Hyperplasias, Adenomas, and Their Implications for Progression into Cancer

Genetic tools for the analysis of human tumors have developed rapidly over the past 20 years. Adrenocortical neoplasms have been subject to multiple analyses using these new genetic tools. Analysis of adrenocortical carcinomas (ACCs) has been complicated by the fact that these tumors tend to exhibit multiple somatic abnormalities, so that identifying driver mutations is complex task. In contrast, benign adrenocortical neoplasms have proven to be a fertile ground for the identification of the genetic causes of adrenocortical adenomas, as well as a variety of adrenocortical hyperplasia. Analysis of cortisol-producing adrenocortical adenomas has revealed alterations leading to enhanced signaling through the cAMP-dependent protein kinase (PKA) pathway. In contrast, macronodular cortisol-producing neoplasias have been shown to result from mutations in the ARMC5 gene, whose function is not yet quite so clear. In contrast, adrenal tumors resulting in excess production of the blood pressure hormone aldosterone almost always result from abnormalities of calcium handling, both in single adenomas and in bilateral hyperplasias. In both cases, there is elevation of a signaling pathway responsible both for hormone secretion and for gland growth and maintenance, thus confirming the linkage of these two output of cellular physiology. The connection between the benign hyperplasia observed in these states and adrenocortical carcinogenesis is not nearly as clear, although genetic studies are beginning to elucidate the relationship between benign and malignant tumors of this gland.

Carney complex: an update

Carney complex (CNC) is a rare autosomal dominant syndrome, characterized by pigmented lesions of the skin and mucosa, cardiac, cutaneous and other myxomas and multiple endocrine tumors. The disease is caused by inactivating mutations or large deletions of the PRKAR1A gene located at 17q22-24 coding for the regulatory subunit type I alpha of protein kinase A (PKA) gene. Most recently, components of the complex have been associated with defects of other PKA subunits, such as the catalytic subunits PRKACA (adrenal hyperplasia) and PRKACB (pigmented spots, myxomas, pituitary adenomas). In this report, we review CNC, its clinical features, diagnosis, treatment and molecular etiology, including PRKAR1A mutations and the newest on PRKACA and PRKACB defects especially as they pertain to adrenal tumors and Cushing's syndrome.

Phosphodiesterase sequence variants may predispose to prostate cancer

We hypothesized that mutations that inactivate phosphodiesterase (PDE) activity and lead to increased cAMP and cyclic guanosine monophosphate levels may be associated with prostate cancer (PCa). We sequenced the entire PDE coding sequences in the DNA of 16 biopsy samples from PCa patients. Novel mutations were confirmed in the somatic or germline state by Sanger sequencing. Data were then compared to the 1000 Genome Project. PDE, CREB and pCREB protein expression was also studied in all samples, in both normal and abnormal tissue, by immunofluorescence. We identified three previously described PDE sequence variants that were significantly more frequent in PCa. Four novel sequence variations, one each in the PDE4B,PDE6C, PDE7B and PDE10A genes, respectively, were also found in the PCa samples. Interestingly, PDE10A and PDE4B novel variants that were present in 19 and 6% of the patients were found in the tumor tissue only. In patients carrying PDE defects, there was pCREB accumulation (P<0.001), and an increase of the pCREB:CREB ratio (patients 0.97±0.03; controls 0.52±0.03; P-value <0.001) by immunohistochemical analysis. We conclude that PDE sequence variants may play a role in the predisposition and/or progression to PCa at the germline and/or somatic state respectively.

Protein kinase A defects and cortisol-producing adrenal tumors

PURPOSE OF REVIEW

Cushing syndrome caused by cortisol-producing adrenal adenomas is a rare condition, associated with high morbidity due to weight gain, diabetes mellitus, osteoporosis, hypertension, muscle weakness, mood disturbance and others. The first gene to be identified as causative of Cushing syndrome was PRKAR1A. We present an update on protein kinase A (PKA) defects and Cushing syndrome.

RECENT FINDINGS

The cyclic AMP-dependent PKA catalytic subunit alpha (PRKACA) hotspot point mutation (c.617A > C [p.Leu206Arg]), leading to an increase of basal PKA activity, and formation of cortisol-producing adenoma has been frequently shown to cause the most common form of adrenocorticotropic hormone-independent Cushing syndrome.

SUMMARY

Somatic PRKACA mutations have been found in up to 50% of patients with adrenal adenomas. Germline PRKACA amplification was also seen in bilateral adrenal hyperplasias. PRKACA activation was associated with higher cortisol levels, smaller tumor size and overt Cushing syndrome. This breakthrough is expected to improve our understanding of how PKA defects lead to Cushing syndrome and may spearhead the development of new, molecularly designed therapies.

Familial Endocrine Syndromes

Endocrine tumors may present as sporadic events or as part of familial endocrine syndromes. Familial endocrine syndromes (or inherited tumor/neoplasm syndromes) are characterized by multiple tumors in multiple organs. Some morphologic findings in endocrine tumor histopathology may prompt the possibility of familial endocrine syndromes, and these recognized histologic features may lead to further molecular genetic evaluation of the patient and family members. Subsequent evaluation for these syndromes in asymptomatic patients and family members may then be performed by genetic screening.

Carney complex and McCune Albright syndrome: an overview of clinical manifestations and human molecular genetics

Endocrine neoplasia syndromes feature a wide spectrum of benign and malignant tumors of endocrine and non-endocrine organs associated with other clinical manifestations. This study outlines the main clinical features, genetic basis, and molecular mechanisms behind two multiple endocrine neoplasia syndromes that share quite a bit of similarities, but one can be inherited whereas the other is always sporadic, Carney complex (CNC) and McCune-Albright (MAS), respectively. Spotty skin pigmentation, cardiac and other myxomas, and different types of endocrine tumors and other characterize Carney complex, which is caused largely by inactivating Protein kinase A, regulatory subunit, type I, Alpha (PRKAR1A) gene mutations. The main features of McCune-Albright are fibrous dysplasia of bone (FD), café-au-lait macules and precocious puberty; the disease is caused by activating mutations in the Guanine Nucleotide-binding protein, Alpha-stimulating activity polypeptide (GNAS) gene which are always somatic. We review the clinical manifestations of the two syndromes and provide an update on their molecular genetics.

Schwannomas and their pathogenesis

Schwannomas may occur spontaneously, or in the context of a familial tumor syndrome such as neurofibromatosis type 2 (NF2), schwannomatosis and Carney's complex. Schwannomas have a variety of morphological appearances, but they behave as World Health Organization (WHO) grade I tumors, and only very rarely undergo malignant transformation. Central to the pathogenesis of these tumors is loss of function of merlin, either by direct genetic change involving the NF2 gene on chromosome 22 or secondarily to merlin inactivation. The genetic pathways and morphological features of schwannomas associated with different genetic syndromes will be discussed. Merlin has multiple functions, including within the nucleus and at the cell membrane, and this review summarizes our current understanding of the mechanisms by which merlin loss is involved in schwannoma pathogenesis, highlighting potential areas for therapeutic intervention.

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.

Deletions of the PRKAR1A locus at 17q24.2-q24.3 in Carney complex: genotype-phenotype correlations and implications for genetic testing

BACKGROUND

Carney complex (CNC) is a multiple neoplasia syndrome caused by PRKAR1A-inactivating mutations. One-third of the patients, however, have no detectable PRKAR1A coding sequence defects. Small deletions of the gene were previously reported in few patients, but large deletions of the chromosomal PRKAR1A locus have not been studied systematically in a large cohort of patients with CNC.

SETTING

A tertiary care referral center was the setting for analysis of an international cohort of patients with CNC.

METHODS

Methods included genome-wide array analysis followed by fluorescent in situ hybridization, mRNA, and other studies as well as a retrospective analysis of clinical information and phenotype-genotype correlation.

RESULTS

We detected 17q24.2-q24.3 deletions of varying size that included the PRKAR1A gene in 11 CNC patients (of 51 tested). Quantitative PCR showed that these patients had significantly lower PRKAR1A mRNA levels. Phenotype varied but was generally severe and included manifestations that are not commonly associated with CNC, presumably due to haploinsufficiency of other genes in addition to PRKAR1A.

CONCLUSIONS

A significant number (21.6%) of patients with CNC that are negative in currently available testing may have PRKAR1A haploinsufficiency due to genomic defects that are not detected by Sanger sequencing. Array-based studies are necessary for diagnostic confirmation of these defects and should be done in patients with unusual and severe phenotypes who are PRKAR1A mutation-negative.

Neurologic complications of cardiac tumors

Cardiac tumors are an uncommon cause for neurologic disease, but if undiagnosed can be associated with devastating neurologic consequences. Primary cardiac tumors, both benign and neoplastic, and metastatic tumors occur. Primary cardiac tumors are more likely to be associated with neurologic embolic complications. Metastatic cardiac tumors are more likely to be associated with valvular distraction, arrhythmia, diminished cardiac output and indirect neurological dysfunction. Primary and metastatic cardiac tumors may result in cerebral metastatic disease. Atrial myxoma, a benign primary cardiac tumor, is the most common cardiac tumor associated with neurologic disease, and most commonly causes cerebral embolization and stroke. The use of thrombolytic therapy for these strokes is controversial. Additionally, delayed manifestations, including aneurysm formation and intracranial hemorrhage, are possible. Aneurysm formation has been described as occurring after removal of the primary tumor. The availability of noninvasive cardiac imaging has significantly helped decrease the neurologic morbidity of cardiac tumors and has led to frequent successful intervention.

Screening for AIP gene mutations in a Han Chinese pituitary adenoma cohort followed by LOH analysis

OBJECTIVE

The aryl hydrocarbon receptor interacting protein gene (AIP) is associated with pituitary adenoma (PA). AIP has not been sequenced in East Asian PA populations, so we performed this study in a Han Chinese cohort.

DESIGN

Our study included six familial PA pedigrees comprising 16 patients and 27 unaffected relatives, as well as 216 sporadic PA (SPA) patients and 100 unrelated healthy controls.

METHODS

AIP sequencing was carried out on genomic DNA isolated from blood samples. Multiplex ligation-dependent probe amplification and microsatellite marker analyses on DNA from the paired tumor tissues were performed for loss of heterozygosity analysis.

RESULTS

We identified three common and four rare single nucleotide polymorphisms (SNPs), one intron insertion, one novel synonymous variant, four novel missense variants, and a reported nonsense mutation in three familial isolated PA (FIPA) cases from the same family. Large genetic deletions were not observed in the germline but were seen in the sporadic tumor DNA from three missense variant carriers. The prevalence of AIP pathogenic variants in PA patients here was low (3.88%), but was higher in somatotropinoma patients (9.30%), especially in young adults (≤30 years) and pediatric (≥18 years) paients (17.24% and 25.00% respectively). All AIP variant patients suffered from macroadenomas. However, the AIP mutation rate in FIPA families was low in this cohort (16.67%, 1/6 families).

CONCLUSION

AIP gene mutation may not be frequent in FIPA or SPA from the Han Chinese population. AIP sequencing and long-term follow-up investigations should be performed for young patients with large PAs and their families with PA predisposition.

Melanotic schwannoma of the cervical spine progressing with pulmonary metastasis: case report

Melanotic schwannoma (MS) is an unusual variant of nerve sheath neoplasm. Only 10% of these tumors will undergo malignant degeneration, with exceedingly rare reported metastasis. We present a 32-year-old woman with a 6-month history of cervical pain and left arm progressive weakness. Neurological examination showed a left upper limb radicular pain, with pyramidal syndrome at C5 level. The magnetic resonance imaging (MRI) study highlighted an intradural extramedullary heterogeneous mass along the spinal cord at the C4-C5 level, slightly hyperintense with T1 and hypointense with T2-weighted sequences, invading the left neural foramen. The patient underwent C3-C5 laminectomy with total resection of a black tumor. In the postoperative period, a patent deficit of shoulder abduction ensued related to the nervous section. Microscopically, compactly fascicles of spindle-shaped cells with pleomorphic and hypercromatic nuclei, dark brown intracellular pigments, as well as some mitotic figures were seen. Immunohistochemical stains for S-100, Human Melanoma Black-45 (HMB-45), and vimentin were positive, with Ki-67 Labelling Index (LI) of 15% compatible with MS. Six months after radiotherapy she presents local recurrence and lung metastatic dissemination of the MS. She underwent left pulmonary segmentectomy, followed by chemotherapy and radiosurgery. The patient developed a febrile neutropenia and worsening of general status, and died after 3 months due to respiratory complications. MS are rare tumors with potential for local recurrence and distal metastasis. Complete surgical resection remains as the treatment of choice, once the uncommon cases with malignant progression shows low response to chemo and radiotherapy.

cAMP/PKA signaling defects in tumors: genetics and tissue-specific pluripotential cell-derived lesions in human and mouse

In the last few years, bench and clinical studies led to significant new insight into how cyclic adenosine monophosphate (cAMP) signaling, the molecular pathway that had been identified in the early 2000s as the one involved in most benign cortisol-producing adrenal hyperplasias, affects adrenocortical growth and development, as well as tumor formation. A major discovery was the identification of tissue-specific pluripotential cells (TSPCs) as the culprit behind tumor formation not only in the adrenal, but also in bone. Discoveries in animal studies complemented a number of clinical observations in patients. Gene identification continued in parallel with mouse and other studies on the cAMP signaling and other pathways.

Germline copy number variations and cancer predisposition

We present an overview of the role of germline copy number variations (CNVs) in cancer predisposition. CNVs represent a significant source of genetic diversity, although the mechanisms by which they influence cancer susceptibility still remain largely unknown. Approximately 100 highly penetrant germline mutant genes are now known to cause cancer predisposition inherited in a Mendelian fashion; in this review, we show that nearly half of these genes have also been observed as rare CNVs associated with cancer. However, these highly penetrant alleles seem to account for less than 5% of all familial cancers. We surmise that most of the genetic risk of cancer in the general population must largely involve genes of low or moderate penetrance. In the last 5 years, studies have demonstrated that although common low penetrant CNVs are modest contributors to cancer individually, their combined impact on cancer predisposition must be taken into account in estimating cancer risk.

17q24.2 microdeletions: a new syndromal entity with intellectual disability, truncal obesity, mood swings and hallucinations

Although microdeletions of the long arm of chromosome 17 are being reported with increasing frequency, deletions of chromosome band 17q24.2 are rare. Here we report four patients with a microdeletion encompassing chromosome band 17q24.2 with a smallest region of overlap of 713 kb containing five Refseq genes and one miRNA. The patients share the phenotypic characteristics, such as intellectual disability (4/4), speech delay (4/4), truncal obesity (4/4), seizures (2/4), hearing loss (3/4) and a particular facial gestalt. Hallucinations and mood swings were also noted in two patients. The PRKCA gene is a very interesting candidate gene for many of the observed phenotypic features, as this gene plays an important role in many cellular processes. Deletion of this gene might explain the observed truncal obesity and could also account for the hallucinations and mood swings seen in two patients, whereas deletion of a CACNG gene cluster might be responsible for the seizures observed in two patients. In one of the patients, the PRKAR1A gene responsible for Carney Complex and the KCNJ2 gene causal for Andersen syndrome are deleted. This is the first report of a patient with a whole gene deletion of the KCNJ2 gene.

Wnt/β-catenin signalling in adrenal physiology and tumour development

Wnt/β-catenin signalling plays essential roles during embryonic development and in adult tissue homeostasis. Canonical signalling through Wnt secreted ligands relies on the control of β-catenin cytoplasmic accumulation and translocation to the nucleus. In this compartment, β-catenin serves as a transcription coactivator for transcription factors such as Lef/Tcf or some nuclear receptors. Constitutive Wnt signalling resulting from inactivation of inhibitors of the pathway or from activating mutations in β-catenin, triggers tumour development in a number of tissues. Analysis of patients' samples and genetically engineered mouse models has shown that Wnt signalling was involved in adrenal development and tumourigenesis. This review will summarise all these recent findings and will focus on some of the mechanisms that may lead to aberrant accumulation of β-catenin in adrenocortical tumours.

In vitro studies of novel PRKAR1A mutants that extend the predicted RIα protein sequence into the 3'-untranslated open reading frame: proteasomal degradation leads to RIα haploinsufficiency and Carney complex

BACKGROUND

Carney complex (CNC) is a multiple endocrine neoplasia syndrome due to inactivating mutations in the PRKAR1A gene that codes for type Iα regulatory (RIα) subunit of protein kinase A. Most PRKAR1A mutations are subject to nonsense mRNA decay (NMD) and, thus, lead to haploinsufficiency.

METHODS AND SETTING

Patient phenotyping for CNC features and DNA, RNA, protein, and transfection studies were carried out at a research center.

RESULTS

We describe in unrelated kindreds with CNC four naturally occurring PRKAR1A mutations (1055del4, 1067del4ins5, 1076delTTins13, and 1142del4) that are predicted to escape NMD because they are located in the last coding exon of the gene. The phenotype of CNC was not different from that in other patients with the condition, although the number of patients was small. Each of the mutations caused a frameshift that led to a new stop codon into the 3' untranslated open reading frame, predicting an elongated protein that, however, was absent in patient-derived cells. After site-directed mutagenesis, in vitro transcription, and cell-free translation experiments, the expected size mutant proteins were present. However, when the mutant constructs were transfected in adrenal (NCI-295), testicular (N-TERA), and embryonic (HEK293) cells and despite the presence of the mutant mRNA, Western blot analysis indicated that there were no longer proteins. The subsequent application of proteasome inhibitors to cells transfected with the mutant constructs led to the detection of the aberrant proteins, although a compound that affects protein folding had no effect. The wild-type protein was also decreased in both patient-derived cells and/or tissues as well as in the in vitro systems used in this study.

CONCLUSIONS

This was the first demonstration of proteasomal degradation of RIα protein variants leading to PRKAR1A haploinsufficiency and CNC, adding protein surveillance to NMD in the cellular mechanisms overseeing RIα synthesis. In agreement with the molecular data, CNC patients bearing PRKAR1A defects that extend the open reading frame did not have a different phenotype, although this has to be confirmed in a larger number of patients.

Genetic predisposition to peripheral nerve neoplasia: diagnostic criteria and pathogenesis of neurofibromatoses, Carney complex, and related syndromes

Neoplasms of the peripheral nerve sheath represent essential clinical manifestations of the syndromes known as the neurofibromatoses. Although involvement of multiple organ systems, including skin, central nervous system, and skeleton, may also be conspicuous, peripheral nerve neoplasia is often the most important and frequent cause of morbidity in these patients. Clinical characteristics of neurofibromatosis type 1 (NF1) and neurofibromatosis type 2 (NF2) have been extensively described and studied during the last century, and the identification of mutations in the NF1 and NF2 genes by contemporary molecular techniques have created a separate multidisciplinary field in genetic medicine. In schwannomatosis, the most recent addition to the neurofibromatosis group, peripheral nervous system involvement is the exclusive (or almost exclusive) clinical manifestation. Although the majority of cases of schwannomatosis are sporadic, approximately one-third occur in families and a subset of these has recently been associated with germline mutations in the tumor suppressor gene SMARCB1/INI1. Other curious syndromes that involve the peripheral nervous system are associated with predominant endocrine manifestations, and include Carney complex and MEN2b, secondary to inactivating mutations in the PRKAR1A gene in a subset, and activating mutations in RET, respectively. In this review, we provide a concise update on the diagnostic criteria, pathology and molecular pathogenesis of these enigmatic syndromes in relation to peripheral nerve sheath neoplasia.

A large family with Carney complex caused by the S147G PRKAR1A mutation shows a unique spectrum of disease including adrenocortical cancer

CONTEXT

Most tumors in Carney complex (CNC) are benign, including primary pigmented nodular adrenocortical disease (PPNAD), the main endocrine tumor in CNC. Adrenocortical cancer (AC) has never been observed in the syndrome. Herein, we describe a large Azorean family with CNC caused by a point mutation in the PRKAR1A gene coding for type 1-α (RIα) regulatory subunit of the cAMP-dependent protein kinase A, in which the index patient presented with AC.

OBJECTIVE

We studied the genotype-phenotype correlation in CNC.

DESIGN AND SETTING

We reported on case series and in vitro testing of the PRKAR1A mutation in a tertiary care referral center.

PATIENTS

Twenty-two members of a family were investigated for Cushing syndrome and other CNC components; their DNA was sequenced for PRKAR1A mutations.

RESULTS

Cushing syndrome due to PPNAD occurred in four patients, including the proposita who presented with AC and three who had Cushing syndrome and/or PPNAD. Lentigines were found in six additional patients who did not have PPNAD. A base substitution (c.439A>G/p.S147G) in PRKAR1A was identified in the proposita, in the three others with PPNAD, in the proposita's twin daughters who had lentigines but no evidence of hypercortisolism, and in five other family members, including one without lentigines or evidence of hypercortisolism. Unlike in other RIα defects, loss of heterozygosity was not observed in AC. The S147G mutation was compared to other expressed PRKAR1A mutations; it led to decreased cAMP and catalytic subunit binding by RIα and increased protein kinase A activity in vitro.

CONCLUSIONS

In a large family with CNC, one amino acid substitution caused a spectrum of adrenal disease that ranged from lack of manifestations to cancer. PPNAD and AC were the only manifestations of CNC in these patients, in addition to lentigines. These data have implications for counseling patients with CNC and are significant in documenting the first case of AC in the context of PPNAD.

Pancreatic ductal and acinar cell neoplasms in Carney complex: a possible new association

CONTEXT

Carney complex (CNC) is a rare disease inherited as an autosomal dominant trait, associated with various tumors, and caused most frequently by inactivation of the PRKAR1A gene.

OBJECTIVES

In our recent investigation of a large cohort of CNC patients, we identified several cases of pancreatic neoplasms. This possible association and PRKAR1A's possible involvement in pancreatic tumor have not been reported previously.

PATIENTS AND METHODS

Nine patients (2.5%) with CNC and pancreatic neoplasms in an international cohort of 354 CNC patients were identified; we studied six of them. Immunohistochemistry and PRKAR1A sequencing were obtained.

RESULTS

Three men and three women with a mean age of 49 yr (range 34-75 yr) had acinar cell carcinoma (n = 2), adenocarcinoma (n = 1), and intraductal pancreatic mucinous neoplasm (n = 3). Five patients had a germline PRKAR1A mutation, including two patients with acinar cell carcinoma, for whom mutations were found in a hemizygous state in the tumor, suggesting loss of heterozygosity. PRKAR1A expression was not detected in five of the six pancreatic neoplasms from CNC patients, whereas the protein was amply expressed on other sporadic pancreatic tumors and normal tissue.

CONCLUSION

An unexpectedly high prevalence of rare pancreatic tumors was found among CNC patients. Immunohistochemistry and loss-of-heterozygosity studies suggest that PRKAR1A could function as a tumor suppressor gene in pancreatic tissue, at least in the context of CNC. Clinicians taking care of CNC patients should be aware of the possible association of CNC with a potentially aggressive pancreatic neoplasm.

[Carney complex]

Carney complex (CNC) is an autosomal dominantly inherited syndrome characterized by spotty skin pigmentation, cardiac and cutaneous myxoma, and endocrine overactivity. Skin pigmentation includes lentigines and blue nevi. Myxomas may occur in breast, skin and heart. Cardiac myxomas may be multiple and occur in any cardiac chamber, and are more prone to recurrence. The most common endocrine gland manifestation is an ACTH-independent Cushing's syndrome due to primary pigmented nodular adrenocortical disease (PPNAD). PPNAD may occur isolated, with no other signs of CNC. Pituitary and thyroid glands and gonads are also involved. The PRKAR1A gene, located in 17 q22-24, encodes type 1A regulatory subunit of protein kinase A. Inactivating germline mutations of this gene are found in 70% of patients with CNC. PRKAR1A is a key component of the c-AMP signaling pathway that has been implicated in endocrine tumorigenesis. Many different mutations have been reported in the PRKAR1A gene. In almost all cases the sequence change was predicted to lead to a premature stop codon and the resultant mutant mRNA was subject to nonsense-mediated mRNA decay. There is no clear genotype-phenotype correlation in patients with CNC. Genetic analysis should be performed in all CNC index cases. All affected patients should be monitored for clinical signs of CNC at least once a year. Genetic diagnosis allows for more effective preparation of more appropriate and effective therapeutic strategies and genetic counseling for patients and gene carriers, and to avoid unnecessary tests to relatives not carrying the gene.

Carney complex and other conditions associated with micronodular adrenal hyperplasias

Carney complex (CNC) is a multiple neoplasia syndrome that is inherited in an autosomal dominant manner and is characterized by skin tumors and pigmented lesions, myxomas, schwannomas, and various endocrine tumors. Inactivating mutations of the PRKAR1A gene coding for the regulatory type I-α (RIα) subunit of protein kinase A (PKA) are responsible for the disease in most CNC patients. The overall penetrance of CNC among PRKAR1A mutation carriers is near 98%. Most PRKAR1A mutations result in premature stop codon generation and lead to nonsense-mediated mRNA decay. CNC is genetically and clinically heterogeneous, with specific mutations providing some genotype-phenotype correlation. 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. Recent evidences demonstrated that dysregulation of cAMP/PKA pathway can modulate other signaling pathways and contributes to adrenocortical tumorigenesis.

Carney complex: Clinical and genetic 2010 update

First described in the mid 1980s, Carney complex is a rare dominantly heritable multiple endocrine neoplasia syndrome that affects endocrine glands as the adrenal cortex, the pituitary and the thyroid. It is associated with many other nonendocrine tumors, including cardiac myxomas, testicular tumors, melanotic schwannoma, breast myxomatosis, and abnormal pigmentation or myxomas of the skin. The Carney complex gene 1 was identified 10 years ago as the regulatory subunit 1A of protein kinase A (PRKAR1A) located at 17q22-24. An inactivating heterozygous germ line mutation of PRKAR1A is observed in about two-thirds of Carney complex patients. This last decade many progresses have been done in the knowledge of this rare disease and its genetics. This review outlines the current state of this knowledge on Carney complex.

Mutations and polymorphisms in the gene encoding regulatory subunit type 1-alpha of protein kinase A (PRKAR1A): an update

PRKAR1A encodes the regulatory subunit type 1-alpha (RIalpha) of the cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA). Inactivating PRKAR1A mutations are known to be responsible for the multiple neoplasia and lentiginosis syndrome Carney complex (CNC). To date, at least 117 pathogenic variants in PRKAR1A have been identified (online database: http://prkar1a.nichd.nih.gov). The majority are subject to nonsense mediated mRNA decay (NMD), leading to RIalpha haploinsufficiency and, as a result, activated cAMP signaling. Recently, it became apparent that CNC may be caused not only by RIalpha haploinsufficiency, but also by the expression of altered RIalpha protein, as proven by analysis of expressed mutations in the gene, consisting of amino acid substitutions and in-frame genetic alterations. In addition, a new subgroup of mutations that potentially escape NMD and result in CNC through altered (rather than missing) protein has been analyzed-these are frame-shifts in the 3' end of the coding sequence that shift the stop codon downstream of the normal one. The mutation detection rate in CNC patients is recently estimated at above 60%; PRKAR1A mutation-negative CNC patients are characterized by significant phenotypic heterogeneity. In this report, we present a comprehensive analysis of all presently known PRKAR1A sequence variations and discuss their molecular context and clinical phenotype.

Clinical and molecular genetics of Carney complex

Carney complex (CNC) is a rare multiple familial neoplasia syndrome that is characterized by multiple types of skin tumors and pigmented lesions, endocrine neoplasms, myxomas and schwannomas and is inherited in an autosomal dominant manner. Clinical and pathologic diagnostic criteria are well established. Over 100 pathogenic variants in the regulatory subunit type 1A (RI-A) of the cAMP-dependent protein kinase (PRKAR1A) have been detected in approximately 60% of CNC patients, most leading to R1A haploinsufficiency. Other CNC-causing genes remain to be identified. Recent studies provided some genotype-phenotype correlations in CNC patients carrying PRKAR1A-inactivating mutations, which provide useful information for genetic counseling and/or prognosis; however, CNC remains a disease with significant clinical heterogeneity. Recent mouse and in vitro studies have shed light into how R1A haploinsufficiency causes tumors. PRKAR1A defects appear to be weak tumorigenic signals for most tissues; Wnt signaling activation and cell cycle dysregulation appear to be important mediators of the tumorigenic effect of a defective R1A.