Pacak–Zhuang syndrome

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The Pacak-Zhuang syndrome is a recently described disease manifestation in females that includes multiple paragangliomas or pheochromocytomas and somatostatinomas (in some), both neuroendocrine tumors, and secondary polycythemia associated with high erythropoietin levels. Paragangliomas in these patients are mainly localized to the abdomen whereas somatostatinomas are found in the second portion of the duodenum, as shown by imaging or biochemistry. [1] This syndrome is of special interest as finding more than one type of neuroendocrine tumor in one individual is unusual. [1] Such co-occurrences are usually seen in patients carrying hereditary syndromes like multiple endocrine neoplasia (MEN), neurofibromatosis 1 (NF1), or von Hippel-Lindau (VHL) disease. [2] [3]

Contents

Genetic pathway

Mutations in the genes encoding alpha subunits of hypoxia-inducible factors (HIF-alpha) have not previously been identified in any cancer. [4]

In the Pacak–Zhuang syndrome, patients have somatic gain of function mutations in the genes encoding for HIF2A, leading to prolonged HIF-2α activity and, thus, an increase in its half-life. [5] While each patient has different nucleic acid changes, all patients are found to have a point mutation near the prolyl-sensing residue site, responsible for HIF-2α hydroxylation. [1]

Diagnosis

Polycythemia

Patients with this syndrome usually have early onset of secondary polycythemia, most of them at birth. They are diagnosed with typical physical characteristics (red cheeks, flushing, swelling of the extremities), which are then confirmed through lab results that show abnormally increased erythropoietin levels. [6]

Tumors

Patients are initially suspicious for paragangliomas when they present with symptoms like hypertension, heart palpitations, headaches, and anxiety; somatostatinomas usually induce diabetes and cholecystitis. From these symptoms, patients undergo biochemical testing from blood and urine samples as well as functional and anatomical imaging to confirm tumor presence. [7]

Other findings

Some patients with this syndrome have also been found to have ocular abnormalities, including bilateral fibrosis upon the optic disc and dilated capillaries. [8]

Treatment

The most common therapies for secondary polycythemia are phlebotomies [9] and, for paraganglioma and/or somatostatinoma in this cohort of patients, surgery accompanied by antihypertensive medication. [1] HIF-2α inhibitor belzutifan led to substantial improvement of symptoms in a patient with Pacak–Zhuang syndrome. [10]

Research direction

Researchers are presently seeking to better characterize the syndrome. [11] Currently, this syndrome is known to only manifest in females.

Related Research Articles

<span class="mw-page-title-main">Von Hippel–Lindau disease</span> Medical condition

Von Hippel–Lindau disease (VHL), also known as VonHippel–Lindau syndrome, is a rare genetic disorder with multisystem involvement. It is characterized by visceral cysts and benign tumors with potential for subsequent malignant transformation. It is a type of phakomatosis that results from a mutation in the Von Hippel–Lindau tumor suppressor gene on chromosome 3p25.3.

<span class="mw-page-title-main">Pheochromocytoma</span> Type of neuroendocrine tumor

Pheochromocytoma is a rare tumor of the adrenal medulla composed of chromaffin cells, also known as pheochromocytes. When a tumor composed of the same cells as a pheochromocytoma develops outside the adrenal gland, it is referred to as a paraganglioma. These neuroendocrine tumors typically release massive amounts of catecholamines, metanephrines, or methoxytyramine, which result in the most common symptoms, including hypertension, tachycardia, and diaphoresis (sweating). Rarely, some tumors may secrete little to no catecholamines, making diagnosis difficult. While tumors of the head and neck are parasympathetic, their sympathetic counterparts are predominantly located in the abdomen and pelvis, particularly concentrated at the organ of Zuckerkandl.

<span class="mw-page-title-main">Multiple endocrine neoplasia</span> Medical condition

Multiple endocrine neoplasia is a condition which encompasses several distinct syndromes featuring tumors of endocrine glands, each with its own characteristic pattern. In some cases, the tumors are malignant, in others, benign. Benign or malignant tumors of nonendocrine tissues occur as components of some of these tumor syndromes.

<span class="mw-page-title-main">Polycythemia</span> Laboratory diagnosis of high hemoglobin content in blood

Polycythemia is a laboratory finding in which the hematocrit and/or hemoglobin concentration are increased in the blood. Polycythemia is sometimes called erythrocytosis, and there is significant overlap in the two findings, but the terms are not the same: polycythemia describes any increase in hematocrit and/or hemoglobin, while erythrocytosis describes an increase specifically in the number of red blood cells in the blood.

<span class="mw-page-title-main">SDHD</span> Protein-coding gene in the species Homo sapiens

Succinate dehydrogenase [ubiquinone] cytochrome b small subunit, mitochondrial (CybS), also known as succinate dehydrogenase complex subunit D (SDHD), is a protein that in humans is encoded by the SDHD gene. Names previously used for SDHD were PGL and PGL1. Succinate dehydrogenase is an important enzyme in both the citric acid cycle and the electron transport chain.

<span class="mw-page-title-main">Succinate dehydrogenase complex subunit C</span>

Succinate dehydrogenase complex subunit C, also known as succinate dehydrogenase cytochrome b560 subunit, mitochondrial, is a protein that in humans is encoded by the SDHC gene. This gene encodes one of four nuclear-encoded subunits that comprise succinate dehydrogenase, also known as mitochondrial complex II, a key enzyme complex of the tricarboxylic acid cycle and aerobic respiratory chains of mitochondria. The encoded protein is one of two integral membrane proteins that anchor other subunits of the complex, which form the catalytic core, to the inner mitochondrial membrane. There are several related pseudogenes for this gene on different chromosomes. Mutations in this gene have been associated with pheochromocytomas and paragangliomas. Alternatively spliced transcript variants have been described.

<span class="mw-page-title-main">Paraganglioma</span> Medical condition

A paraganglioma is a rare neuroendocrine neoplasm that may develop at various body sites. When the same type of tumor is found in the adrenal gland, they are referred to as a pheochromocytoma. They are rare tumors, with an overall estimated incidence of 1/300,000. There is no test that determines benign from malignant tumors; long-term follow-up is therefore recommended for all individuals with paraganglioma.

Hypoxia-inducible factors (HIFs) are transcription factors that respond to decreases in available oxygen in the cellular environment, or hypoxia. They are only present in parahoxozoan animals.

Phakomatoses, also known neurocutaneous syndromes, are a group of multisystemic diseases that most prominently affect structures primarily derived from the ectoderm such as the central nervous system, skin and eyes. The majority of phakomatoses are single-gene disorders that may be inherited in an autosomal dominant, autosomal recessive or X-linked pattern. Presentations may vary dramatically between patients with the same particular syndrome due to mosaicism, variable expressivity, and penetrance.

<span class="mw-page-title-main">SDHB</span>

Succinate dehydrogenase [ubiquinone] iron-sulfur subunit, mitochondrial (SDHB) also known as iron-sulfur subunit of complex II (Ip) is a protein that in humans is encoded by the SDHB gene.

<span class="mw-page-title-main">Tumor metabolome</span>

The study of the tumor metabolism, also known as tumor metabolome describes the different characteristic metabolic changes in tumor cells. The characteristic attributes of the tumor metabolome are high glycolytic enzyme activities, the expression of the pyruvate kinase isoenzyme type M2, increased channeling of glucose carbons into synthetic processes, such as nucleic acid, amino acid and phospholipid synthesis, a high rate of pyrimidine and purine de novo synthesis, a low ratio of Adenosine triphosphate and Guanosine triphosphate to Cytidine triphosphate and Uridine triphosphate, low Adenosine monophosphate levels, high glutaminolytic capacities, release of immunosuppressive substances and dependency on methionine.

<span class="mw-page-title-main">Hemangioblastoma</span> Medical condition

Hemangioblastomas, or haemangioblastomas, are vascular tumors of the central nervous system that originate from the vascular system, usually during middle age. Sometimes, these tumors occur in other sites such as the spinal cord and retina. They may be associated with other diseases such as polycythemia, pancreatic cysts and Von Hippel–Lindau syndrome. Hemangioblastomas are most commonly composed of stromal cells in small blood vessels and usually occur in the cerebellum, brainstem or spinal cord. They are classed as grade I tumors under the World Health Organization's classification system.

<span class="mw-page-title-main">Von Hippel–Lindau tumor suppressor</span> Mammalian protein found in Homo sapiens

The Von Hippel–Lindau tumor suppressor also known as pVHL is a protein that, in humans, is encoded by the VHL gene. Mutations of the VHL gene are associated with Von Hippel–Lindau disease.

<span class="mw-page-title-main">HIF1A</span> Protein-coding gene in the species Homo sapiens

Hypoxia-inducible factor 1-alpha, also known as HIF-1-alpha, is a subunit of a heterodimeric transcription factor hypoxia-inducible factor 1 (HIF-1) that is encoded by the HIF1A gene. The Nobel Prize in Physiology or Medicine 2019 was awarded for the discovery of HIF.

<span class="mw-page-title-main">EPAS1</span> Protein-coding gene in the species Homo sapiens

Endothelial PAS domain-containing protein 1 is a protein that is encoded by the EPAS1 gene in mammals. It is a type of hypoxia-inducible factor, a group of transcription factors involved in the physiological response to oxygen concentration. The gene is active under hypoxic conditions. It is also important in the development of the heart, and for maintaining the catecholamine balance required for protection of the heart. Mutation often leads to neuroendocrine tumors.

<span class="mw-page-title-main">EGLN1</span>

Hypoxia-inducible factor prolyl hydroxylase 2 (HIF-PH2), or prolyl hydroxylase domain-containing protein 2 (PHD2), is an enzyme encoded by the EGLN1 gene. It is also known as Egl nine homolog 1. PHD2 is a α-ketoglutarate/2-oxoglutarate-dependent hydroxylase, a superfamily non-haem iron-containing proteins. In humans, PHD2 is one of the three isoforms of hypoxia-inducible factor-proline dioxygenase, which is also known as HIF prolyl-hydroxylase.

<span class="mw-page-title-main">IDH2</span>

Isocitrate dehydrogenase [NADP], mitochondrial is an enzyme that in humans is encoded by the IDH2 gene.

Hypoxia-inducible factor-proline dioxygenase (EC 1.14.11.29, HIF hydroxylase) is an enzyme with systematic name hypoxia-inducible factor-L-proline, 2-oxoglutarate:oxygen oxidoreductase (4-hydroxylating). This enzyme catalyses the following chemical reaction

<span class="mw-page-title-main">SDHAF2</span>

Succinate dehydrogenase complex assembly factor 2, formerly known as SDH5 and also known as SDH assembly factor 2 or SDHAF2 is a protein that in humans is encoded by the SDHAF2 gene. This gene encodes a mitochondrial protein needed for the flavination of a succinate dehydrogenase complex subunit required for activity of the complex. Mutations in this gene are associated with pheochromocytoma and paraganglioma.

<span class="mw-page-title-main">Belzutifan</span> Chemical compound

Belzutifan, sold under the brand name Welireg, is an anti-cancer medication used for the treatment of von Hippel–Lindau disease-associated renal cell carcinoma. It is taken by mouth. Belzutifan is an hypoxia-inducible factor-2 alpha (HIF-2α) inhibitor.

References

  1. 1 2 3 4 Pacak K, Jochmanova I, Prodanov T, et al: New syndrome of paraganglioma and somatostatinoma associated with polycythemia. J Clin Oncol, 31(13):1690-1698, 2013.
  2. ↑ Lenders JW, Eisenhofer G, Mannelli M, Pacak K. Phaeochromocytoma. Lancet 2005; 366:665-675.
  3. ↑ Gimenez-Roqueplo AP, Dahia PL, Robledo M. An update on the genetics of paraganglioma, pheochromocytoma, and associated hereditary syndromes. Horm Metab Res 2012; 44:328-333.
  4. ↑ "Research Briefs". 13 May 2013.
  5. ↑ Jochmanova I, Yang C, Zhuang Z, Pacak K. Hypoxia-inducible factor signaling in pheochromocytoma: turning the rudder in the right direction. J Natl Cancer Inst 2013; 105:1270-1283.
  6. ↑ Zhuang Z, Yang C, Lorenzo F, Merino M, Fojo T, Kebebew E, Popovic V, Stratakis CA, Prchal JT, Pacak K. Somatic HIF2A gain-of-function mutations in paraganglioma with polycythemia. N Engl J Med 2012; 367:922-930.
  7. ↑ "Clinical Practice Guidelines" (PDF). endocrine Society.[ dead link ]
  8. ↑ Pacak K, Chew E, Pappo A, Yang C, Lorenzo F, Wilson M, Aronow M, Young J, Popovic V, and Zhuang Z. Ocular Manifestations of Hypoxia-Inducible Factor-2A Paranglioma-Somatostatinoma-Polycythemia Syndrome. J Opthal 2014. DOI: 10.1016/j.ophtha.2014.06.019
  9. ↑ Tefferi A, Thiele J, Vardiman JW: The 2008 World Health Organization classification system for myeloproliferative neoplasms: order out of chaos. Cancer 115 (17): 3842-7, 2009.
  10. ↑ Kamihara, Junne; Hamilton, Kayla V.; Pollard, Jessica A.; Clinton, Catherine M.; Madden, Jill A.; Lin, Jasmine; Imamovic, Alma; Wall, Catherine B.; Wassner, Ari J.; Weil, Brent R.; Heeney, Matthew M. (2021-11-25). "Belzutifan, a Potent HIF2α Inhibitor, in the Pacak–Zhuang Syndrome". New England Journal of Medicine. 385 (22): 2059–2065. doi: 10.1056/NEJMoa2110051 . ISSN   0028-4793. PMID   34818480. S2CID   244651726.
  11. ↑ "Postbac Posters 2014 Joan Nambuba - NICHD Connection - Science@NICHD".
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