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

The clinical characteristics and pathogenic variants of primary pigmented nodular adrenocortical disease in 210 patients: a systematic review

Aims

Primary pigmented nodular adrenocortical disease (PPNAD), as a rare kind of Cushing's syndrome, is frequently misdiagnosed. To get a better understanding of the disease, we analyzed the clinical characteristics and pathogenic variants of PPNAD.

Methods

Databases were searched, and the pathogenic variants and clinical manifestations of patients were summarized from the relevant articles.

Results

A total of 210 patients in 86 articles were enrolled with a median age of 22 and a female-to-male ratio of 2:1. Sixty-six (31.43%) patients were combined with Carney complex (CNC) and 94.29% were combined with osteoporosis/osteopenia. Among 151 patients who underwent genetic testing, 87.42% (132/151) had pathogenic variants. Six gene mutations (PRKAR1A, PDE11A, PRKACA, CTNNB1, PDE8B, and ARMC5) were detected in the patients. The most common mutation was PKAR1A, accounting for 79.47% (120/151). There was a significant correlation between PRKAR1A pathogenic variant and spotty skin pigmentation in CNC concurrent with PPNAD (p < 0.05). Among pregnant patients with PPNAD, those without surgical treatment and with bilateral adrenalectomy suffered from a high-risk perinatal period. However, patients with unilateral adrenalectomy presented a safe perinatal period.

Conclusions

For young patients with Cushing's syndrome, especially female patients with spotty skin pigmentation and osteoporosis/osteopenia, PPNAD should be considered. Unilateral adrenal resection may be considered as an option for women with fertility needs. In view of the difficulty of PPNAD diagnosis, genetic testing before surgery might be a reasonable option. Patients with PPNAD with spotty skin pigmentation should consider the PRKAR1A pathogenic variant and pay attention to CNC.

Systematic review registration

https://www.crd.york.ac.uk/prospero, identifier CRD42023416988.

Primary pigmented nodular adrenal disease presenting as hypertensive crisis

We present a case of a young girl who presented with hypertensive crisis and recent onset weight gain with hirsutism. On evaluation for Cushing syndrome (CS), her cortisol concentration was high, showed a paradoxical cortisol rise on dexamethasone suppression and the adrenocorticotropic hormone (ACTH) was low. Adrenal imaging showed normal adrenal morphology. Genetic diagnosis of primary pigmented nodular adrenal disease (PPNAD) was made. She was operated for bilateral adrenalectomy and histopathology confirmed the diagnosis of PPNAD. Our case highlights the rare aetiology of PPNAD as a cause of CS resulting in a hypertensive crisis. To the best of our knowledge, this is the youngest case of ACTH independent CS presenting as hypertensive encephalopathy.

ARMC5 variants in PRKAR1A-mutated patients modify cortisol levels and Cushing's syndrome

Mutations in the protein kinase A (PKA) regulatory subunit type 1A (PRKAR1A) and armadillo repeat-containing 5 (ARMC5) genes cause Cushing's syndrome (CS) due to primary pigmented nodular adrenocortical disease (PPNAD) and primary bilateral macronodular adrenocortical hyperplasia (PBMAH), respectively. Between the two genes, ARMC5 is highly polymorphic with several variants in the population, whereas PRKAR1A has very little, if any, non-pathogenic variation in its coding sequence. We tested the hypothesis that ARMC5 variants may affect the clinical presentation of PPNAD and CS among patients with PRKAR1A mutations. In this study, 91 patients with PPNAD due to PRKAR1A mutations were tested for abnormal cortisol secretion or CS and for ARMC5 sequence variants. Abnormal cortisol secretion was present in 71 of 74 patients with ARMC5 variants, whereas 11 of 17 patients negative for ARMC5 variants did not have hypercortisolemia. The presence of ARMC5 variants was a statistically strong predictor of CS among patients with PRKAR1A mutations (P < 0.001). Among patients with CS due to PPNAD, ARMC5 variants were associated with lower cortisol levels at baseline (P = 0.04) and after high dose dexamethasone administration (P = 0.02). The ARMC5 p.I170V variant increased ARMC5 protein accumulation in vitro and decreased viability of NCI-H295 cells (but not HEK 293T cells). PPNAD tissues with ARMC5 variants showed stronger ARMC5 protein expression than those that carried a normal ARMC5 sequence. Taken together, our results suggest that ARMC5 variants among patients with PPNAD due to PRKAR1A defects may play the role of a genetic modifier for the presence and severity of hypercortisolemia.

Update on primary micronodular bilateral adrenocortical diseases

PURPOSE OF REVIEW

Primary micronodular bilateral adrenocortical hyperplasias (MiBAH) are rare challenging diseases. Important progress in understanding its pathophysiology and genetics occurred in the last two decades. We summarize those progress and recent data on investigation and therapy of MiBAH focusing on primary pigmented nodular adrenocortical disease (PPNAD).

RECENT FINDINGS

Larger recent cohorts of PPNAD patients from various countries have confirmed their variable Cushing's syndrome phenotypes. Age of onset is earlier than other ACTH-independent Cushing's syndrome causes and the youngest case have now occurred at 15 months. Two retrospective studies identified an increased risk of osteoporotic fractures in PPNAD as compared with other Cushing's syndrome causes. The utility of 6-day oral dexamethasone test to produce a paradoxical increase of urinary-free cortisol in PPNAD was confirmed but the mean fold of increase was of 48%, less than previously suggested. Several new genetic variants of the PRKAR1A gene have been reported in PPNAD or Carney complex (CNC). Remission of Cushing's syndrome with unilateral adrenalectomy was reported in a few patients with PPNAD.

SUMMARY

MiBAH, PPNAD and CNC are rare challenging diseases, but with combined expert clinical and genetic approaches a comprehensive investigation and prevention strategy can be offered to affected patients and families.

Primary pigmented nodular adrenocortical disease (PPNAD): single centre experience

Background Primary pigmented nodular adrenocortical disease (PPNAD) is a rare cause of Cushing's syndrome (CS) in childhood. We describe a case series of patients presenting at our centre along with a review of the literature. Methods A retrospective analysis of six index cases and one family were done for demographic features, hormonal profile, imaging findings, genetic mutation status, histopathologic findings and follow-up details. Diagnosis was based on biochemistry and confirmed with histopathology and or genetic mutation. All patients had suppressed 8 am adrenocorticotropic hormone (ACTH) (<10 pg/mL) despite evidence of hypercortisolism. Results The mean age in our cohort was 8.2 years (range 15 months to 20 years). All patients presented with overt CS, including one patient with cyclic Cushing's. Three patients had additional features of Carney complex (CNC). Imaging did not reveal any obvious mass lesions on computed tomography (CT), the classical beaded appearance was present in only two of the patients. Mutation analysis was positive in three patients. Five patients underwent bilateral adrenalectomy and had features of PPNAD on histopathology. Conclusions PPNAD is a rare cause of ACTH-independent CS in childhood and may signal underlying CNC. Patients with younger age of onset with overt CS may still have a mutation in the PRKAR1A gene and warrant genetic testing.

Familial Forms of Cushing Syndrome in Primary Pigmented Nodular Adrenocortical Disease Presenting with Short Stature and Insidious Symptoms: A Clinical Series

Cushing syndrome (CS) is a rare disease in children, frequently associated with subtle or periodic symptoms that may delay its diagnosis. Weight gain and growth failure, the hallmarks of hypercortisolism in pediatrics, may be inconsistent, especially in ACTH-independent forms of CS. Primary pigmented nodular adrenocortical disease (PPNAD) is the rarest form of ACTH-independent CS, and can be associated with endocrine and nonendocrine tumors, forming the Carney complex (CNC). Recently, phenotype/genotype correlations have been described with particular forms of CNC where PPNAD is isolated or associated only with skin lesions. We present four familial series of CS due to isolated PPNAD, and compare them to available data from the literature. We discuss the clinical and molecular findings, and underline challenges in diagnosing PPNAD in childhood.

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.

Primary pigmented nodular adrenocortical disease: literature review and case report of a 6-year-old boy

Cushing's syndrome is rare in childhood and is usually caused by a pituitary adenoma. Primary hyperfunction of adrenal glands is less frequent, particularly primary pigmented nodular adrenocortical disease (PPNAD). It occurs usually in children and adolescents, with female preponderance, while Cushing's disease has increased frequency in prepubertal males. A case of a 6-year-old boy is presented with isolated non-familiar PPNAD. The clinical pattern involved Cushingoid appearance, hypertension, virilization and depressive mood. Laboratory analyses showed loss of circadian rhythm of cortisol, undetectable adrenocorticotropic hormone (ACTH) level, impaired fasting glucose, polycythemia and elevated white blood count (WBC). Radiology investigation revealed a slightly enlarged medial branch of the left adrenal gland and a normal right one, so a unilateral adrenalectomy was performed. Pathohistology described multiple dark brownish pigmented nodules of various sizes confined to the cortex. Contralateral adrenalectomy was done 3 months later. Follow-up of 3 years was uneventful, except for one adrenal crisis during an intercurrent respiratory illness.

PKA regulatory subunit 1A inactivating mutation induces serotonin signaling in primary pigmented nodular adrenal disease

Primary pigmented nodular adrenocortical disease (PPNAD) is a rare cause of ACTH-independent hypercortisolism. The disease is primarily caused by germline mutations of the protein kinase A (PKA) regulatory subunit 1A (PRKAR1A) gene, which induces constitutive activation of PKA in adrenocortical cells. Hypercortisolism is thought to result from PKA hyperactivity, but PPNAD tissues exhibit features of neuroendocrine differentiation, which may lead to stimulation of steroidogenesis by abnormally expressed neurotransmitters. We hypothesized that serotonin (5-HT) may participate in the pathophysiology of PPNAD-associated hypercortisolism. We show that PPNAD tissues overexpress the 5-HT synthesizing enzyme tryptophan hydroxylase type 2 (Tph2) and the serotonin receptors types 4, 6, and 7, leading to formation of an illicit stimulatory serotonergic loop whose pharmacological inhibition in vitro decreases cortisol production. In the human PPNAD cell line CAR47, the PKA inhibitor H-89 decreases 5-HT₄ and 5-HT₇ receptor expression. Moreover, in the human adrenocortical cell line H295R, inhibition of PRKAR1A expression increases the expression of Tph2 and 5-HT_4/6/7 receptors, an effect that is blocked by H-89. These findings show that the serotonergic process observed in PPNAD tissues results from PKA activation by PRKAR1A mutations. They also suggest that Tph inhibitors may represent efficient treatments of hypercortisolism in patients with PPNAD.

Identification of a novel mutation of the PRKAR1A gene in a patient with Carney complex with significant osteoporosis and recurrent fractures

OBJECTIVE

Carney complex (CNC) is a rare autosomal dominant multiple neoplasia syndrome characterized by the presence of endocrine and non-endocrine tumors. More than 125 different germline mutations of the protein Kinase A type 1-α regulatory subunit (PRKAR1A) gene have been reported. We present a novel PRKAR1A gene germline mutation in a patient with severe osteoporosis and recurrent vertebral fractures.

DESIGN

Clinical case report.

CASE REPORT

A 53-year-old male with a medical history of surgically removed recurrent cardiac myxomas was evaluated for repeated low-pressure vertebral fractures and severe osteoporosis. Physical examination revealed spotty skin pigmentation of the lower extremities and papules in the nuchal and thoracic region. The presence of hypercortisolism due to micronodular adrenal disease and the history of cardiac myxomas suggested the diagnosis of CNC; the patient underwent detailed imaging investigation and genetic testing.

METHODS

Standard imaging and clinical testing; DNA was sequenced by the Sanger method.

RESULTS

Sequence analysis from peripheral lymphocytes DNA revealed a novel heterozygous point mutation at codon 172 of exon 2 (c.172G>T) of the PRKAR1A gene, resulting in early termination of the PRKAR1A transcript [p.Glu58Ter (E58X)].

CONCLUSION

We report a novel point mutation of the PRKAR1A gene in a patient with CNC who presented with significant osteoporosis and fractures. Low bone mineral density along with recurrent myxomas should point to the diagnosis of CNC.

Cushing's syndrome

Chronic exposure to excess glucorticoids results in diverse manifestations of Cushing's syndrome, including debilitating morbidities and increased mortality. Genetic and molecular mechanisms responsible for excess cortisol secretion by primary adrenal lesions and adrenocorticotropic hormone (ACTH) secretion from corticotroph or ectopic tumours have been identified. New biochemical and imaging diagnostic approaches and progress in surgical and radiotherapy techniques have improved the management of patients. The therapeutic goal is to normalise tissue exposure to cortisol to reverse increased morbidity and mortality. Optimum treatment consisting of selective and complete resection of the causative tumour is necessay to allow eventual normalisation of the hypothalamic-pituitary-adrenal axis, maintenance of pituitary function, and avoidance of tumour recurrence. The development of new drugs offers clinicians several choices to treat patients with residual cortisol excess. However, for patients affected by this challenging syndrome, the long-term effects and comorbidities associated with hypercortisolism need ongoing care.

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.

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.

Genetic aspects of adrenocortical tumours and hyperplasias

Adrenocortical tumours (ACT), which include adenomas, carcinomas and adrenal hyperplasia, may be associated with genetic syndromes, such as Li-Fraumeni syndrome, Beckwith-Wiedemann syndrome, multiple endocrine neoplasia type 1, familial adenomatous polyposis and Carney complex. Genetic defects have been found to be responsible for the disease in most of these syndromes, allowing genetic counselling to affected patients and family members. Here, we summarize the clinical criteria of these hereditary syndromes and briefly describe the genetic alterations related to them. In addition, we discuss the involvement of various genetic defects in the development of sporadic adrenocortical tumours.

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.

An unusual presentation of Carney complex with diffuse primary pigmented nodular adrenocortical disease on one adrenal gland and a nonpigmented adrenocortical adenoma and focal primary pigmented nodular adrenocortical disease on the other

A 24-year-old female patient with cushingoid appearance was admitted in May 2000. The endocrine studies showed ACTH-independent Cushing's syndrome. A 2-day high-dose dexamethasone suppression test (HDDST) revealed paradoxical increase of 24 h urinary free cortisol (UFC). Abdominal computed tomography demonstrated a left adrenal nodule (3 x 2 cm in diameter). An adrenal scintigram with ¹³¹I-6β-iodomethyl-19-norcholesterol showed uptake of the isotope in the left adrenal gland and non-visualization in the right adrenal gland throughout the examination course. A retroperitoneoscopic left total adrenalectomy was performed in July 2000. The cut surface of the left adrenal was yellow-tan grossly. Microscopically, the left adrenal nodule contained a nonpigmented adrenocortical adenoma (NP) and another focal primary pigmented nodular adrenocortical disease (PPNAD, FP) mixed lesion. The immunohistochemical studies of CYP17 demonstrate positive in NP and FP of the left adrenal gland. Very low baseline morning plasma cortisol (0.97 μg/dL) and subnormal ACTH (8.16 pg/mL) levels were measured 1.5 months after left adrenalectomy. Right adrenal gland recovered its function 6 months after left adrenalectomy. Plasma cortisol could be suppressed to 3.47 μg/dL by overnight low-dose dexamethasone suppression test 65 months after left adrenalectomy. Cushingoid features still did not appear 122 months after left adrenalectomy. In May 2011, this patient was readmitted due to cushingoid characteristics. Paradoxical rise of 24-h UFC to 2-day HDDST was demonstrated. Ultrasonography of thyroid showed bilateral thyroid cysts. Subtotal right adrenalectomy about 80% of right adrenal was performed. Diffuse PPNAD of the right adrenal was proved pathologically. Immunohischemical stain for CYP17 is positive in the right adrenal gland but weaker positive than that in the left adrenal gland. The genetic study of the peripheral blood, left adrenocortical nodule, and right PPNAD all showed p.R16X (c.46C>T) mutation of the PRKAR1A 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.