Carney complex: the first 20 years

Amyloid-Driven Allostery

The fields of allostery and amyloid-related pathologies, such as Parkinson's disease (PD), have been extensively explored individually, but less is known about how amyloids control allostery. Recent advancements have revealed that amyloids can drive allosteric effects in both intrinsically disordered proteins, such as alpha-synuclein (αS), and multi-domain signaling proteins, such as protein kinase A (PKA). Amyloid-driven allostery plays a central role in explaining the mechanisms of gain-of-pathological-function mutations in αS (e.g. E46K, which causes early PD onset) and loss-of-physiological-function mutations in PKA (e.g. A211D, which predisposes to tumors). This review highlights allosteric effects of disease-related mutations and how they can cause exposure of amyloidogenic regions, leading to amyloids that are either toxic or cause aberrant signaling. We also discuss multiple potential modulators of these allosteric effects, such as MgATP and kinase substrates, opening future opportunities to improve current pharmacological interventions against αS and PKA-related pathologies. Overall, we show that amyloid-driven allosteric models are useful to explain the mechanisms underlying disease-related mutations.

Male Infertility associated with a Novel PRKAR1A Mutation in Carney Complex

Carney Complex (CNC) is a rare syndrome characterized by spotty skin pigmentation and multiple neoplasms, notably cardiac myxomas, schwannomas, and endocrine tumours. It is often inherited in an autosomal dominant manner with PRKAR1A gene mutations found in the majority of cases. Male infertility is established as part of the CNC phenotype and is largely associated with Large cell calcifying Sertoli cell tumours (LCCSCT). We describe a case of a 30-year-old male patient with Carney Complex, presenting with severe oligoasthenozoospermia and primary pigmented nodular adrenocortical disease (PPNAD). During follow-up consults, the severe oligozoospermia and impaired semen motility persisted and the patient was also diagnosed with a recurring cardiac myxoma and LCCSCT. Molecular testing identified a novel PRKAR1A mutation involving a deletion of exons 4 to 7. Our findings suggest this mutation causes PRKAR1A haploinsufficiency, which may be directly linked to male infertility, irrespective of the presence of testicular tumours. Accordingly, in male patients with CNC, detection of a PRKAR1A gene mutation may serve as a predictive marker for infertility. This case report illustrates the importance of early consideration and management of infertility in male patients diagnosed with CNC.

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.

Recurrent multi-cameral cardiac myxomas in a child with Carney complex

Cardiac myxoma is a relatively rare tumour, usually solitary, that occurs primarily in the left atrium of adults, but comprises only 30% of cardiac tumours in children. We recently treated a 12-year-old girl with multiple recurrent myxomas in three cardiac chambers(following surgical resection 3 years earlier). Genomic analysis showed the PKAR1A mutation typical for Carney complex.

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.

Carney complex- why thorough medical history taking is so important - report of three cases and review of the literature

PURPOSE

To present a new case series and to review the literature on Carney complex (CNC) with an emphasis on highlighting key clinical features of the disease and pointing out possibilities of shortening the diagnostic process.

METHOD

Searches of PubMed, identifying relevant reports up to April 2022.

RESULTS

CNC is a rare, autosomally dominant inherited neoplasia -endocrinopathy syndrome with high clinical variability, even among members of the same family. Data on length of diagnostic process are scarce with numerous case series reporting a diagnostic delay of decades. Suggestions to shorten the diagnostic process includes awareness of the multi-faceted clinical presentations of CNC, thorough history taking of index patients and family members and awareness of diagnostic pitfalls. Importantly, unusual symptom combinations should alert the clinician to suspect a rare endocrinopathy syndrome such as CNC. Already present and coming on the horizon are databases and novel phenotyping technologies that will aid endocrinologists in their quest for timely diagnosis.

CONCLUSION

In this review, we examine the current state of knowledge in CNC and suggest avenues for shortening the diagnostic journey for the afflicted patients.

Genetic and clinical phenotypic analysis of carney complex with external auditory canal myxoma

Background: Mutations in PRKAR1A gene can lead to Carney complex (CNC), and most CNC patients develop cardiac and cutaneous myxomas. In particular, cardiac myxomas are a common cause of mortality in CNC patients. Cutaneous myxomas of the external ear are extremely rare, and do not have any specific clinical features

Methods: In this retrospective study, we analyzed the clinical and genetic data of the proband and his family and fifty whole blood control samples selected from the molecular genetic database of our hospital. Whole exome DNA sequencing analysis was used to detect the mutation in the peripheral blood samples.

Results: The results of the clinical analysis showed the presence of spotty skin pigmentation and external auditory canal myxoma in the proband as well as in his sister and mother. Whole-exome DNA sequencing showed a novel heterozygous mutation in the PRKAR1A gene i.e., c.824_825delAG (p.Gln275Leufs*2), in the proband and his sister and mother.

Conclusion: In conclusion, the family members had the same autosomal dominant PRKAR1A mutation. DNA sequencing revealed a novel c.824_825delAG in exon 9 of PRKAR1A. This pathogenic mutation has not been reported previously, and may be related to the occurrence of external auditory canal myxomas and spotty pigmentation. This study broadens the genotypic spectrum of PRKAR1A mutations in CNC.

Protein kinase A drives paracrine crisis and WNT4-dependent testis tumor in Carney complex

Large-cell calcifying Sertoli cell tumors (LCCSCTs) are among the most frequent lesions occurring in male Carney complex (CNC) patients. Although they constitute a key diagnostic criterion for this rare multiple neoplasia syndrome resulting from inactivating mutations of the tumor suppressor PRKAR1A, leading to unrepressed PKA activity, LCCSCT pathogenesis and origin remain elusive. Mouse models targeting Prkar1a inactivation in all somatic populations or separately in each cell type were generated to decipher the molecular and paracrine networks involved in the induction of CNC testis lesions. We demonstrate that the Prkar1a mutation was required in both stromal and Sertoli cells for the occurrence of LCCSCTs. Integrative analyses comparing transcriptomic, immunohistological data and phenotype of mutant mouse combinations led to the understanding of human LCCSCT pathogenesis and demonstrated PKA-induced paracrine molecular circuits in which the aberrant WNT4 signal production is a limiting step in shaping intratubular lesions and tumor expansion both in a mouse model and in human CNC testes.

State-selective frustration as a key driver of allosteric pluripotency

Allosteric pluripotency arises when an allosteric effector switches from agonist to antagonist depending on the experimental conditions. For example, the Rp-cAMPS ligand of Protein Kinase A (PKA) switches from agonist to antagonist as the MgATP concentration increases and/or the kinase substrate affinity or concentration decreases. Understanding allosteric pluripotency is essential to design effective allosteric therapeutics with minimal side effects. Allosteric pluripotency of PKA arises from divergent allosteric responses of two homologous tandem cAMP-binding domains, resulting in a free energy landscape for the Rp-cAMPS-bound PKA regulatory subunit R1a in which the ground state is kinase inhibition-incompetent and the kinase inhibition-competent state is excited. The magnitude of the free energy difference between the ground non-inhibitory and excited inhibitory states (ΔG_R,Gap) relative to the effective free energy of R1a binding to the catalytic subunit of PKA (ΔG_R:C) dictates whether the antagonism-to-agonism switch occurs. However, the key drivers of ΔG_R,Gap are not fully understood. Here, by analyzing an R1a mutant that selectively silences allosteric pluripotency, we show that a major determinant of ΔG_R,Gap unexpectedly arises from state-selective frustration in the ground inhibition-incompetent state of Rp-cAMPS-bound R1a. Such frustration is caused by steric clashes between the phosphate-binding cassette and the helices preceding the lid, which interact with the phosphate and base of Rp-cAMPS, respectively. These clashes are absent in the excited inhibitory state, thus reducing the ΔG_R,Gap to values comparable to ΔG_R:C, as needed for allosteric pluripotency to occur. The resulting model of allosteric pluripotency is anticipated to assist the design of effective allosteric modulators.

The Rp-cAMPS ligand of protein kinase A switches from agonist to antagonist depending on metabolite and proteomic contexts. We show that the state-selective frustration is a key driver of this allosteric pluripotency phenomenon.

A novel mutation in PRKAR1A gene in a patient with Carney complex presenting with pituitary macroadenoma, acromegaly, Cushing's syndrome and recurrent atrial myxoma

Carney complex (CNC) is a rare syndrome of multiple endocrine and non-endocrine tumors. In this paper we present a 23-year-old Iranian woman with CNC who harbored a novel mutation (c.642dupT) in PRKAR1A gene. This patient presented with pituitary macroadenoma, acromegaly, recurrent atrial myxoma, Cushing's syndrome secondary to primary pigmented nodular adrenocortical disease and pigmented schwanoma of the skin. PRKAR1A gene was PCR amplified using genomic DNA and analyzed for sequence variants which revealed the novel mutation resulting in substitution of amino acid cysteine instead of the naturally occurring valine in the peptide chain and a premature stop codon at position 18 (V215CfsX18). This change leads to development of tumors in different organs due to lack of tumor suppressive activity secondary to failure of synthesis of the related protein.

Genetics of Acromegaly and Gigantism

Growth hormone (GH)-secreting pituitary tumours represent the most genetically determined pituitary tumour type. This is true both for germline and somatic mutations. Germline mutations occur in several known genes (AIP, PRKAR1A, GPR101, GNAS, MEN1, CDKN1B, SDHx, MAX) as well as familial cases with currently unknown genes, while somatic mutations in GNAS are present in up to 40% of tumours. If the disease starts before the fusion of the epiphysis, then accelerated growth and increased final height, or gigantism, can develop, where a genetic background can be identified in half of the cases. Hereditary GH-secreting pituitary adenoma (PA) can manifest as isolated tumours, familial isolated pituitary adenoma (FIPA) including cases with AIP mutations or GPR101 duplications (X-linked acrogigantism, XLAG) or can be a part of systemic diseases like multiple endocrine neoplasia type 1 or type 4, McCune-Albright syndrome, Carney complex or phaeochromocytoma/paraganglioma-pituitary adenoma association. Family history and a search for associated syndromic manifestations can help to draw attention to genetic causes; many of these are now tested as part of gene panels. Identifying genetic mutations allows appropriate screening of associated comorbidities as well as finding affected family members before the clinical manifestation of the disease. This review focuses on germline and somatic mutations predisposing to acromegaly and gigantism.

Allosteric inhibition explained through conformational ensembles sampling distinct "mixed" states

Allosteric modulation provides an effective avenue for selective and potent enzyme inhibition. Here, we summarize and critically discuss recent advances on the mechanisms of allosteric partial agonists for three representative signalling enzymes activated by cyclic nucleotides: the cAMP-dependent protein kinase (PKA), the cGMP-dependent protein kinase (PKG), and the exchange protein activated by cAMP (EPAC). The comparative analysis of partial agonism in PKA, PKG and EPAC reveals a common emerging theme, i.e. the sampling of distinct “mixed” conformational states, either within a single domain or between distinct domains. Here, we show how such “mixed” states play a crucial role in explaining the observed functional response, i.e. partial agonism and allosteric pluripotency, as well as in maximizing inhibition while minimizing potency losses. In addition, by combining Nuclear Magnetic Resonance (NMR), Molecular Dynamics (MD) simulations and Ensemble Allosteric Modeling (EAM), we also show how to map the free-energy landscape of conformational ensembles containing “mixed” states. By discussing selected case studies, we illustrate how MD simulations and EAM complement NMR to quantitatively relate protein dynamics to function. The resulting NMR- and MD-based EAMs are anticipated to inform not only the design of new generations of highly selective allosteric inhibitors, but also the choice of multidrug combinations.

Coexistence of Growth Hormone Deficiency and Pituitary Microadenoma in a Child with Unique Mosaic Turner Syndrome: A Case Report and Literature Review

Turner syndrome (TS) is a genetic disorder with phenotypic heterogeneity caused by the monosomy or structural abnormalities of the X chromosome, and it has a prevalence of about 1/2500 females live birth. The variable clinical features of TS include short stature, gonadal failure, and skeletal dysplasia. The association with growth hormone (GH) deficiency or other hypopituitarism in TS is extremely rare, with only a few case reports published in the literature. Here, we report the first case of a patient with mosaic TS with complete GH deficiency and pituitary microadenoma, and we include the literature review. During the work-up of the patient for severe short stature, three GH provocation tests revealed peak GH levels of less than 5 ng/mL, which was compatible with complete GH deficiency. Sella magnetic resonance imaging showed an 8 mm non-enhancing pituitary adenoma with mild superior displacement of the optic chiasm. Karyotyping revealed the presence of ring chromosome X and monosomy X (46,X,r(X)/45,X/46,X,psu dic r(X;X)), which indicated a mosaic TS. It is important to consider not only chromosome analyses in females with short stature, but also the possibility of the coexistence of complete GH deficiency accompanying pituitary lesions in TS. In conclusion, the present study reports the first case of GH deficiency and pituitary adenoma in a patient with rare mosaic TS, which extends the genotype-phenotype spectrum for TS.

Clinical and Molecular Update on Genetic Causes of Pituitary Adenomas

Pituitary adenomas are benign tumors with variable functional characteristics that can have a significant impact on patients. The majority arise sporadically, but an inherited genetic susceptibility is increasingly being recognized. Recent advances in genetics have widened the scope of our understanding of pituitary tumorigenesis. The clinical and genetic characteristics of pituitary adenomas that develop in the setting of germline-mosaic and somatic GNAS mutations (McCune-Albright syndrome and sporadic acromegaly), germline MEN1 mutations (multiple endocrine neoplasia type 1), and germline PRKAR1A mutations (Carney complex) have been well described. Non-syndromic familial cases of isolated pituitary tumors can occur as familial isolated pituitary adenomas (FIPA); mutations/deletions of the AIP gene have been found in a minority of these. Genetic alterations in GPR101 have been identified recently as causing X-linked acro-gigantism (X-LAG) leading to very early-onset pediatric gigantism. Associations of pituitary adenomas with other tumors have been described in syndromes like multiple endocrine neoplasia type 4, pheochromocytoma-paraganglioma with pituitary adenoma association (3PAs) syndrome and some of their genetic causes have been elucidated. The genetic etiologies of a significant proportions of sporadic corticotropinomas have recently been identified with the discovery of USP8 and USP48 mutations. The elucidation of genetic and molecular pathophysiology in pituitary adenomas is a key factor for better patient management and effective follow-up.

Allosteric pluripotency as revealed by protein kinase A

The functional response of a signaling system to an allosteric stimulus often depends on subcellular conditions, a phenomenon known as pluripotent allostery. For example, a single allosteric modulator, Rp-cAMPS, of the prototypical protein kinase A (PKA) switches from antagonist to agonist depending on MgATP levels. However, the mechanism underlying such pluripotent allostery has remained elusive for decades. Using nuclear magnetic resonance spectroscopy, ensemble models, kinase assays, and molecular dynamics simulations, we show that allosteric pluripotency arises from surprisingly divergent responses of highly homologous tandem domains. The differential responses perturb domain-domain interactions and remodel the free-energy landscape of inhibitory excited states sampled by the regulatory subunit of PKA. The resulting activation threshold values are comparable to the effective free energy of regulatory and catalytic subunit binding, which depends on metabolites, substrates, and mutations, explaining pluripotent allostery and warranting a general redefinition of allosteric targets to include specific subcellular environments.

Rare Association between Giant Right Ventricular Myxoma and Right Coronary Artery Tumour Blush with Complicating Pulmonary Tumour Embolism

Cardiac myxoma is a benign primary cardiac tumour which can present with nonspecific symptoms of right heart failure, syncope, exertional dyspnea, and pulmonary embolism. We describe a case of a right ventricular myxoma complicated with bilateral pulmonary embolism, with an incidental right coronary artery fistula but otherwise normal coronary anatomy on coronary angiogram. This case report emphasizes the importance of performing a transesophageal echo in the setting of pulmonary embolism to search for the origin of thrombus/tumour, and performing a comprehensive assessment is also necessary to rule out coronary artery disease, coronary artery fistula that may also represent a tumour blush.

Clinical features and surgical results of cardiac myxoma in Carney complex

BACKGROUND

We sought to analyze clinical features and surgical results of 10 cases of cardiac myxomas in Carney complex (CNC).

METHODS

Between January 2003 and December 2013, 10 patients with cardiac myxomas in CNC underwent surgical resection. Associated cardiac lesions included moderate and severe mitral regurgitation in two cases, and moderate tricuspid regurgitation in one case. Age, gender, the incidence of arterial embolism, the rate of multiple cardiac myxomas, and the recurrence rate after resections of cardiac myxoma were compared between isolated cardiac myxomas and cardiac myxomas in CNC.

RESULTS

The incidence of cardiac myxoma in CNC was 1.74% (10/574). There were no deaths following surgery. There was one late death due to cerebral embolism 40 months following a reoperation (10%). A significant difference was found in the age, the incidence of arterial embolism, the rate of multiple cardiac myxomas, and the recurrence rate after resection of cardiac myxoma between cardiac myxoma in CNC and isolated cardiac myxoma (P < 0.05). There was no significant difference in gender between cardiac myxoma in CNC and isolated cardiac myxoma (P > 0.05).

CONCLUSIONS

Complex myxomas in CNS present at an earlier age, are more prevalent in women than in men, are more often multicentric, with a higher rate of arterial embolism and a high recurrence rate after resection. Close follow-up for cardiac myxoma in CNC after surgery is necessary due to the high recurrence rate.

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.

Carney complex review: Genetic features

Carney complex is a multiple neoplasia syndrome having endocrine and non-endocrine manifestations. Diagnostic criteria include myxoma, lentigines, and primary pigmented nodular adrenocortical disease, amongst other signs/symptoms. In most cases it is an autosomal dominant disease, and diagnosis therefore requires study and follow-up of the family members. Inactivating mutations of the PRKAR1A gene were identified as the main cause of the disease, although since 2015 other disease-related genes, including PRKACA and PRKACB activating mutations, have also been related with Carney complex. This review will address the genetic aspects related to Carney complex.

Syndrome mit breitem Tumorspektrum

Die klinische Diagnose erblicher Tumorsyndrome ist ein wesentlicher Bestandteil der humangenetischen Beratung. Bei seltenen Syndromen, die mit einem breiten Spektrum an Tumoren und phänotypischen Überschneidungen einhergehen, ist dies nicht immer einfach. In diesem Artikel sollen deshalb die typischen und wegweisenden Merkmale der wichtigsten seltenen Tumordispositionssyndrome mit breitem Tumorspektrum herausgearbeitet werden. Hierzu gehören der Carney-Komplex, das Cowden-Syndrom, die juvenile Polyposis, das Li-Fraumeni-Syndrom und das Peutz-Jeghers-Syndrom. Darüber hinaus sind auch die derzeit empfohlenen Früherkennungsuntersuchungen dargestellt, die meist eine interdisziplinäre Betreuung der Patienten erforderlich machen.

Organ-sparing surgery for large cell calcifying Sertoli cell tumour in a patient with Carney complex

Carney complex is a rare genetic disease characterised by a complex of myxomas, spotty pigmentation and endocrine overactivity. At diagnosis, about one-third of male patients presents with testicular tumours, namely large cell calcifying Sertoli cell tumours, which are often multicentric and/or bilateral and have a low malignant potential. Although radical orchiectomy is the gold standard for the treatment of testicular neoplasms, a conservative approach with partial orchiectomy or tumourectomy may be the best treatment option for these patients, allowing the preservation of endocrine function, fertility and body image. We present a case of a 19-year-old man with a known history of Carney complex with early identification of a small testicular tumour treated with organ-sparing surgery.

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.

An adolescent with large cell calcifying sertoli cell tumor of the testis and undiagnosed Carney Complex: A case report

Carney Complex (CNC) is a rare autosomal dominant condition with characteristic clinical presentation, tumor development, and unique genetic mutation. We present a unique case and literature review of CNC in which two neoplasms characteristic of this complex were initially diagnosed through cytological fine needle aspirate specimens, leading to the identification of CNC, with subsequent surgical and cytogenetic confirmation. Diagn. Cytopathol. 2017;45:634-639. © 2017 Wiley Periodicals, Inc.

Prkar1a gene knockout in the pancreas leads to neuroendocrine tumorigenesis

Carney complex (CNC) is a rare disease associated with multiple neoplasias, including a predisposition to pancreatic tumors; it is caused most frequently by the inactivation of the PRKAR1A gene, a regulator of the cyclic AMP (cAMP)-dependent kinase (PKA). The method used was to create null alleles of prkar1a in mouse cells expressing pdx1 (Δ-Prkar1a). We found that these mice developed endocrine or mixed endocrine/acinar cell carcinomas with 100% penetrance by the age of 4-5 months. Malignant behavior of the tumors was seen as evidenced by stromal invasion and metastasis to locoregional lymph nodes. Histologically, most tumors exhibited an organoid pattern as seen in the islet-cell tumors. Biochemically, the lesions exhibited high PKA activity, as one would expect from deleting prkar1a The primary neuroendocrine nature of these tumor cells was confirmed by immunohistochemical staining and electron microscopy, the latter revealing the characteristic granules. Although the Δ-Prkar1a mice developed hypoglycemia after overnight fasting, insulin and glucagon levels in the plasma were normal. Negative immunohistochemical staining for the most commonly produced peptides (insulin, c-peptide, glucagon, gastrin and somatostatin) suggested that these tumors were non-functioning. We hypothesize that the recently identified multipotent pdx1+/insulin- cell in adult pancreas, gives rise to endocrine or mixed endocrine/acinar pancreatic malignancies with complete prkar1a deficiency. In conclusion, this mouse model supports the role of prkar1a as a tumor suppressor gene in the pancreas and points to the PKA pathway as a possible therapeutic target for these lesions.

Screening for genetic causes of growth hormone hypersecretion

Growth hormone (GH) secreting pituitary tumors may be caused by genetic abnormalities in a variety of genes including AIP, MEN1, CDKN1B, and PRKAR1A. These can lead to GH secreting pituitary adenomas as an isolated occurrence (e.g. as aggressive sporadic adenomas or in familial isolated pituitary adenomas (FIPA)) or as part of syndromic conditions such as MEN1 or Carney complex. These tumors have more aggressive features than sporadic acromegaly, including a younger age at disease onset and larger tumor size, and they can be challenging to manage. In addition to mutations or deletions, copy number variation at the GPR101 locus may also lead to mixed GH and prolactin secreting pituitary adenomas in the setting of X-linked acrogigantism (X-LAG syndrome). In X-LAG syndrome and in McCune Albright syndrome, mosaicism for GPR101 duplications and activating GNAS1 mutations, respectively, contribute to the genetic pathogenesis. As only 5% of pituitary adenomas have a known cause, efficient deployment of genetic testing requires detailed knowledge of clinical characteristics and potential associated syndromic features in the patient and their family.

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.

A Novel Inherited Mutation in PRKAR1A Abrogates PreRNA Splicing in a Carney Complex Family

BACKGROUND

Carney complex (CNC) is an autosomal dominant inherited disease, characterized by spotty skin pigmentation, cardiac and cutaneous myxomas, and endocrine overactivity. We report on a Chinese CNC family with a novel mutation in the protein kinase A regulatory subunit 1 (PRKAR1A) gene.

METHODS

Target-exome sequencing was performed to identify the mutation of PRKAR1A in 2 members of the CNC family.

RESULTS

The proband was a young man with typical CNC, including pigmentation, cutaneous myxomas, cardiac myxoma, Sertoli cell tumour of his left testis, and multiple hypoechoic thyroid nodules. His mother also had CNC with skin pigmentation, cutaneous myxomas, and a cardiac myxoma. Target-exome capture analysis revealed that the proband and the mother carried a novel heterozygous mutation in the exon 6 splicing donor site of PRKAR1A. Sequencing analysis of myxoma messenger RNA revealed that the mutation abrogated exon 6 preRNA splicing, leading to a frameshift starting at Valine 185 and premature translation termination in intron 6. The truncated enzyme lacks the functional cyclic adenosine monophosphate (cAMP) binding domain at the C-terminus, causing PRKAR1A haploinsufficiency.

CONCLUSIONS

In this study we report on a novel splicing mutation in the PRKAR1A gene that adds to the genetic heterogeneity of CNC.

60 YEARS OF NEUROENDOCRINOLOGY: Acromegaly

Acromegaly (ACM) is a chronic, progressive disorder caused by the persistent hypersecretion of GH, in the vast majority of cases secreted by a pituitary adenoma. The consequent increase in IGF1 (a GH-induced liver protein) is responsible for most clinical features and for the systemic complications associated with increased mortality. The clinical diagnosis, based on symptoms related to GH excess or the presence of a pituitary mass, is often delayed many years because of the slow progression of the disease. Initial testing relies on measuring the serum IGF1 concentration. The oral glucose tolerance test with concomitant GH measurement is the gold-standard diagnostic test. The therapeutic options for ACM are surgery, medical treatment, and radiotherapy (RT). The outcome of surgery is very good for microadenomas (80-90% cure rate), but at least half of the macroadenomas (most frequently encountered in ACM patients) are not cured surgically. Somatostatin analogs are mainly indicated after surgical failure. Currently their routine use as primary therapy is not recommended. Dopamine agonists are useful in a minority of cases. Pegvisomant is indicated for patients refractory to surgery and other medical treatments. RT is employed sparingly, in cases of persistent disease activity despite other treatments, due to its long-term side effects. With complex, combined treatment, at least three-quarters of the cases are controlled according to current criteria. With proper control of the disease, the specific complications are partially improved and the mortality rate is close to that of the background population.

Successful pregnancy and delivery in a patient with Carney complex: implications for anesthesiologists

Carney complex is an autosomal dominant condition with widespread manifestations, including cardiac myxomas, nerve sheath tumors, and endocrinopathies. Although often associated with infertility, there are several reports of successful pregnancies in patients with Carney complex. However, none of the previous reports describe anesthetic considerations. Herein, we present a patient with Carney complex who successfully delivered vaginally with labor epidural analgesia.

Medical and Surgical Management of Carney Complex

Carney complex is a rare, autosomal dominant genetic disorder that consists of multiple myxomatous lesions and endocrine abnormalities, including skin lesions, cardiac myxomas, primary pigmented nodular adrenocortical disease, and acromegaly. This review discusses the medical and surgical treatment of patients with Carney complex.

Familial pituitary tumors

Pituitary adenomas are benign intracranial neoplasms that present a major clinical concern due to hormone overproduction and/or tumor mass effects. The majority of pituitary adenomas occur sporadically; however, familial cases are increasingly being recognized, such as multiple endocrine neoplasia type 1 (MEN1), Carney complex (CNC), and familial isolated pituitary adenoma (FIPA). Familial pituitary tumors appear to differ from their sporadic counterparts both in their genetic basis and in clinical characteristics. Evidence suggests that, especially in MEN1 and FIPA, tumors are more aggressive and affect patients at a younger age, therefore justifying the importance of early diagnosis, while in Carney complex pituitary hyperplasia is common. The genetic alterations responsible for the formation of familial pituitary syndromes include the MEN1 gene, responsible for about 80% of MEN1 cases, the regulatory subunit of the protein kinase A, PRKAR1A, responsible for about 70% of Carney complex cases, and AIP, the gene coding the aryl hydrocarbon receptor interacting protein, responsible for about 20% of FIPA cases. Rarely other genes have also been found responsible for familial pituitary adenoma cases. McCune-Albright syndrome (MAS) also has a genetic origin due to mosaic mutations in the G protein-coupled α subunit coded by the GNAS1 gene. In this chapter, we summarize the genetic and clinical characteristics of these familial pituitary syndromes and MAS.

Genetic studies in a coexistence of acromegaly, pheochromocytoma, gastrointestinal stromal tumor (GIST) and thyroid follicular adenoma

We report on an adult woman with rare coexistence of acromegaly, pheochromocytoma (PHEO), gastrointestinal stromal tumor (GIST), intestinal polyposis, and thyroid follicular adenoma. At the age of 56, she was diagnosed with acromegaly caused by a pituitary macroadenoma, treated by transsphenoidal surgery, radiotherapy, and octreotide. During routine colonoscopy, multiple polyps were identified as tubular adenomas with high-grade dysplasia on histology. Years later, an abdominal mass of 8.0 x 6.2 cm was detected by routine ultrasound. Surgical exploration revealed an adrenal mass and another tumor adhered to the lesser gastric curvature, which were removed. Pathology confirmed the diagnosis of PHEO and GIST. PHEO immunohistochemistry was negative for GHRH. During follow-up, nodular goiter was found with normal levels of calcitonin and inconclusive cytology. Near-total thyroidectomy was performed, revealing a follicular adenoma. Her family history was negative for all of these tumor types. Genetic analysis for PHEO/paraganglioma genes (SDH A-D, SDHAF2, RET, VHL, TMEM127, and MAX), and pituitary-related genes (AIP, MEN1, and p27) were negative. Though the finding of PHEO and acromegaly with multiple other tumors could be a fortuitous coexistence, we suggest that this case may represent a new variant of MEN syndrome with a de novo germline mutation in a not yet identified gene.

The complex of myxomas, spotty skin pigmentation and endocrine overactivity (Carney complex): imaging findings with clinical and pathological correlation

The complex of myxomas, spotty skin pigmentation and endocrine overactivity, or Carney complex (CNC), is a familial multiple endocrine neoplasia and lentiginosis syndrome. CNC is inherited in an autosomal dominant manner and is genetically heterogeneous. Its features overlap those of McCune-Albright syndrome and other multiple endocrine neoplasia (MEN) syndromes. Spotty skin pigmentation is the major clinical manifestation of the syndrome, followed by multicentric heart myxomas, which occur at a young age and are the lethal component of the disease. Myxomas may also occur on the skin (eyelid, external ear canal and nipple) and the breast. Breast myxomas, when present, are multiple and bilateral among female CNC patients, an entity which is also described as “breast-myxomatosis” and is a characteristic feature of the syndrome. Affected CNC patients often have tumours of two or more endocrine glands, including primary pigmented nodular adrenocortical disease (PPNAD), an adrenocorticotropin hormone (ACTH)-independent cause of Cushing’s syndrome, growth hormone (GH)-secreting and prolactin (PRL)-secreting pituitary adenomas, thyroid adenomas or carcinomas, testicular neoplasms (large-cell calcifying Sertoli cell tumours [LCCSCT]) and ovarian lesions (cysts and cancinomas). Additional infrequent but characteristic manifestations of CNC are psammomatous melanotic schwannomas (PMS), breast ductal adenomas (DAs) with tubular features, and osteochondromyxomas or “Carney bone tumour”.

Teaching Points

• Almost 60 % of the known CNC kindreds have a germline inactivating mutations in the PRKAR1A gene.

• Spotty skin pigmentation is the major clinical manifestation of CNC, followed by heart myxomas.

• Indicative imaging signs of PPNAD are contour abnormality and hypodense spots within the gland.

• Two breast tumours may present in CNC: myxoid fibroadenomas (breast myxomatosis) and ductal adenomas.

• Additional findings of CNC are psammomatous melanotic schwannomas (PMSs) and osteochondromyxomas.

Novel Mutation in PRKAR1A in Carney Complex

A case of Carney complex in a Korean patient is presented. The patient had the characteristics of Carney complex including skin lesions, positive family history, and multiple myxomas including a superficial angiomyxoma in the perianal area. An extensive genetic analysis revealed a novel mutation in the protein kinase A type I-a regulatory subunit (PRKAR1A) gene, but not in the phosphodiesterase type 11A (PDE11A) gene. This is the first case wherein extensive genetic studies were performed in a patient with Carney complex in Korea.

Familial isolated pituitary adenomas: an emerging clinical entity

Familial pituitary tumors are increasingly recognized. While some of these cases are related to wellknown syndromic conditions such as multiple endocrine neoplasia type 1 (MEN1) or Carney complex, others belong to the familial isolated pituitary adenoma (FIPA) patient group. The discovery of heterozygous, loss-of-function germline mutations in the gene encoding the aryl hydrocarbon receptor interacting protein (AIP) in 2006 has subsequently enabled the identification of a mutation in this gene in 20% of FIPA families and 20% of childhood-onset simplex soma- totroph adenomas. The exact mechanism by which the lack of AIP leads to pituitary adenomas is not clear. AIP mutations cause a low penetrance autosomal dominant disease with often a distinct phenotype characterized by young-onset, aggressive, large GH, mixed GH and PRL or PRL-secreting adenomas. This review aims to summarize currently available clinical data on AIP mutation-positive and negative FIPA patients.

Skin lesions in hereditary endocrine tumor syndromes

OBJECTIVE

To review the main cutaneous manifestations of hereditary endocrine tumor syndromes and discuss currently known molecular mechanisms involved in their pathogenesis.

METHODS

On the basis of our collective experience and a comprehensive MEDLINE literature search of the English-language literature published between January 1957 and September 2010 using the search terms "skin," "cutaneous," "multiple endocrine neoplasia," "Carney complex," and "McCune-Albright syndrome," we reviewed the dermatologic findings in multiple endocrine neoplasia type 1 and type 2, Carney complex, and McCune-Albright syndrome.

RESULTS

Although the category of hereditary endocrine tumor syndromes consists of a broad spectrum of conditions, only the aforementioned few are prominently associated with cutaneous features. Because the cutaneous findings associated with these diseases are generally benign, they are often ignored or dismissed as ancillary findings in the context of severe systemic involvement. Accordingly, the pertinent literature is relatively scarce and often fails to provide a comprehensive insight about this issue. Nevertheless, timely recognition of such dermatologic manifestations may have a critical role in the early diagnosis and appropriate management of the related syndromes. Moreover, specific genotype-phenotype correlations may convey important prognostic implications.

CONCLUSION

Many physicians are unfamiliar with the cutaneous findings in the hereditary endocrine tumor syndromes described in this review. Nonetheless, knowledge of their existence can have a major role in establishing an early diagnosis of these syndromes and determining the patient's prognosis.

The differential diagnosis of familial lentiginosis syndromes

Cutaneous markers of systemic disease are vital for clinicians to recognize. This chapter outlines familial lentiginosis syndromes that include Peutz-Jeghers syndrome, Carney Complex, the PTEN hamartomatous syndromes, and LEOPARD/Noonan syndrome. The inheritance of these syndromes is autosomal dominant; they also share characteristic skin findings that offer a clue to their recognition and treatment. We will discuss the clinical presentation of these disorders, with a focus on the dermatological manifestations, and will provide an update on the molecular mechanisms involved. Recognition of cutaneous markers associated with these rare familial cancer syndromes provides the opportunity to pursue early surveillance for malignancies, as well as genetic counseling.

[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.

Pathogenesis of pituitary tumors

Pituitary adenomas may hypersecrete hormones (including prolactin, growth hormone and adrenocorticotropic hormone, and rarely follicle-stimulating hormone, luteinizing hormone or TSH) or may be nonfunctional. Despite their high prevalence in the general population, these tumors are invariably benign and exhibit features of differentiated pituitary cell function as well as premature proliferative arrest. Pathogenesis of dysregulated pituitary cell proliferation and unrestrained hormone hypersecretion may be mediated by hypothalamic, intrapituitary and/or peripheral factors. Altered expression of pituitary cell cycle genes, activation of pituitary selective oncoproteins or loss of pituitary suppressor factors may be associated with aberrant growth factor signaling. Considerable information on the etiology of these tumors has been derived from transgenic animal models, which may not accurately and universally reflect human tumor pathophysiology. Understanding subcellular mechanisms that underlie pituitary tumorigenesis will enable development of tumor aggression markers as well as novel targeted therapies.

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.

Solid tumors associated with multiple endocrine neoplasias

We present an update on molecular and clinical genetics of solid tumors associated with the various multiple endocrine neoplasias (MEN) syndromes. MEN type 1 (MEN1) describes the association of pituitary, parathyroid, and pancreatic islet cell tumors with a variety of many other lesions. MEN type 2 (MEN2) conditions represent at least four different syndromes that associate pheochromocytoma with medullary thyroid carcinoma, hyperparathyroidism, and a number of other manifestations. Other pheochromocytoma-associated syndromes include von Hippel-Lindau disease; neurofibromatosis 1; the recently defined paraganglioma syndromes type 1, 3, and 4; Carney-Stratakis syndrome; and the Carney triad. Carney-Stratakis syndrome is characterized by the association of paragangliomas and familial gastrointestinal stromal tumors. In the Carney triad, patients can manifest gastrointestinal stromal tumors, lung chondroma, paraganglioma, adrenal adenoma and pheochromocytoma, esophageal leiomyoma, and other conditions. The Carney complex is yet another form of MEN that is characterized by skin tumors and pigmented lesions, myxomas, schwannomas, and various endocrine neoplasias.

Familial pituitary adenomas

Pituitary adenomas are benign intracranial neoplasms that present a major clinical concern because of hormonal overproduction or compression symptoms of adjacent structures. Most arise in a sporadic setting with a small percentage developing as a part of familial syndromes such as multiple endocrine neoplasia type 1 (MEN1), Carney complex (CNC), and the recently described familial isolated pituitary adenomas (FIPA) and MEN-4. While the genetic alterations responsible for the formation of sporadic adenomas remain largely unknown, considerable advances have been made in defining culprit genes in these familial syndromes. Mutations in MEN1 and PRKAR1A genes are found in the majority of MEN1 and CNC patients, respectively. About 15% of FIPA kindreds present with mutations of the aryl hydrocarbon receptor-interacting protein (AIP) gene. Mutations in the CDKN1B gene, encoding p27(Kip)¹ were identified in MEN4 cases. Familial tumours appear to differ from their sporadic counterparts not only in genetic basis but also in clinical characteristics. Evidence suggests that, especially in MEN1 and FIPA, they are more aggressive and affect patients at younger age, therefore justifying the importance of early diagnosis. In this review, we summarize the genetic and clinical characteristics of these familial pituitary adenomas.