Germline deletion and a somatic mutation of the PRKAR1A gene in a Carney complex-related pituitary adenoma

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.

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.

USP8 and TP53 Drivers are Associated with CNV in a Corticotroph Adenoma Cohort Enriched for Aggressive Tumors

CONTEXT

Pituitary corticotroph adenomas are rare tumors that can be associated with excess adrenocorticotropin (ACTH) and adrenal cortisol production, resulting in the clinically debilitating endocrine condition Cushing disease. A subset of corticotroph tumors behave aggressively, and genomic drivers behind the development of these tumors are largely unknown.

OBJECTIVE

To investigate genomic drivers of corticotroph tumors at risk for aggressive behavior.

DESIGN

Whole-exome sequencing of patient-matched corticotroph tumor and normal deoxyribonucleic acid (DNA) from a patient cohort enriched for tumors at risk for aggressive behavior.

SETTING

Tertiary care center.

PATIENTS

Twenty-seven corticotroph tumors from 22 patients were analyzed. Twelve tumors were macroadenomas, of which 6 were silent ACTH tumors, 2 were Crooke's cell tumors, and 1 was a corticotroph carcinoma.

INTERVENTION

Whole-exome sequencing.

MAIN OUTCOME MEASURE

Somatic mutation genomic biomarkers.

RESULTS

We found recurrent somatic mutations in USP8 and TP53 genes, both with higher allelic fractions than other somatic mutations. These mutations were mutually exclusive, with TP53 mutations occurring only in USP8 wildtype (WT) tumors, indicating they may be independent driver genes. USP8-WT tumors were characterized by extensive somatic copy number variation compared with USP8-mutated tumors. Independent of molecular driver status, we found an association between invasiveness, macroadenomas, and aneuploidy.

CONCLUSIONS

Our data suggest that corticotroph tumors may be categorized into a USP8-mutated, genome-stable subtype versus a USP8-WT, genome-disrupted subtype, the latter of which has a TP53-mutated subtype with high level of chromosome instability. These findings could help identify high risk corticotroph tumors, namely those with widespread CNV, that may need closer monitoring and more aggressive treatment.

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.

Case Report with Review of the Literature: Uveal Melanoma in a Patient with Carney Complex - Another Rare Component of the Syndrome?

A 74-year-old woman with Carney complex (CNC) and complaints of poor vision was found, on ophthalmic examination, to have a pigmented tumor involving the peripheral choroid and ciliary body in her right eye. The eye was enucleated and showed a ciliochoroidal melanoma with marked pleomorphism. The tumor did not recur or metastasize after almost 10 years of follow-up, and the patient died of unrelated causes. Molecular studies revealed a complex genome with multiple whole-chromosome losses including monosomy of chromosomes 1, 2 (including loss of CNC2at 2p16), 14, 17 (including loss of a copy of PRAKA1 at 17q24.2), 18, 19, 21, 22, and X. No monosomy 3 was observed. This is only the second case of uveal melanoma in a patient with CNC, raising the possibility that this might represent a rare component of this syndrome.

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.

Growth hormone-producing pituitary adenomas in childhood and young adulthood: clinical features and outcomes

PURPOSE

Growth hormone (GH)-producing pituitary adenomas (PAs) in childhood or young adulthood are rare, and the details surrounding these tumors remain enigmatic. We present the clinical, pathological and genetic features of this disease.

METHODS

We identified 25 patients aged 20 years or younger with GH-producing PAs who underwent surgery between 2003 and 2016 at Toranomon Hospital in Tokyo. We retrospectively reviewed the clinical data, treatment outcomes and pathological features of these patients to shed light on childhood acromegaly.

RESULTS

The cohort comprised 14 male and 11 female patients whose average age at the time of surgery was 17.3 years. Germline AIP mutations were present in 5 of 13 patients examined, and Carney complex was identified in 2 of 25 patients. The mean maximum tumor diameter was 26.7 mm, and total resection assessed during surgery was achieved in 17 patients. Based on their respective pathological findings, patients were divided into the following 4 groups: sparsely granulated adenomas (5), densely granulated (DG) adenomas (6), plurihormonal adenomas (9), and silent subtype 3 (SS3) adenomas (5). During the mean follow-up period of 50.3 months, complete endocrinological remission was achieved in 14 of 25 patients (56%) by surgery alone and in 19 patients (76%) after postoperative adjuvant therapy.

CONCLUSIONS

GH-producing PAs in young patients are intriguing and difficult to treat due to their distinct tumor characteristics, including a lower incidence of the DG subtype and a higher incidence of SS3 adenomas and genetic abnormalities. Therefore, multi-modal therapies are essential to achieve optimal clinical outcomes.

Molecular markers in pituitary tumors

PURPOSE OF REVIEW

This review summarizes our current understanding of the mechanisms and factors involved in pituitary tumorigenesis. It provides a comprehensive review on the role of genetic mutations, epigenetics, oncogenes, tumor suppressor genes, cell cycle deregulation, and highlights recent findings of altered micro-RNA and long noncoding RNA expression in pituitary tumors.

RECENT FINDINGS

This article provides a concise summary of our knowledge regarding oncogenes, tumor suppressor genes, and cell cycle deregulation in pituitary tumors. Additionally, it highlights new findings in epigenetics and altered micro-RNA and long noncoding RNA expression in pituitary tumors.

SUMMARY

Improved understanding of the mechanism(s) and candidates implicated in pituitary tumorigenesis may result in the identification of new therapeutic targets in pituitary tumors.

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.