Sclerochoroidal calcification associated with Gitelman syndrome

Ocular manifestations of the genetic renal tubulopathies

BACKGROUND

The genetic tubulopathies are rare and heterogenous disorders that are often difficult to identify. This study examined the tubulopathy-causing genes for ocular associations that suggested their genetic basis and, in some cases, the affected gene.

METHODS

Sixty-seven genes from the Genomics England renal tubulopathy panel were reviewed for ocular features, and for retinal expression in the Human Protein Atlas and an ocular phenotype in mouse models in the Mouse Genome Informatics database. The genes resulted in disease affecting the proximal tubules (n = 24); the thick ascending limb of the loop of Henle (n = 10); the distal convoluted tubule (n = 15); or the collecting duct (n = 18).

RESULTS

Twenty-five of the tubulopathy-associated genes (37%) had ocular features reported in human disease, 49 (73%) were expressed in the retina, although often at low levels, and 16 (24%) of the corresponding mouse models had an ocular phenotype. Ocular abnormalities were more common in genes affected in the proximal tubulopathies (17/24, 71%) than elsewhere (7/43, 16%). They included structural features (coloboma, microphthalmia); refractive errors (myopia, astigmatism); crystal deposition (in oxalosis, cystinosis) and sclerochoroidal calcification (in Bartter, Gitelman syndromes). Retinal atrophy was common in the mitochondrial-associated tubulopathies. Structural abnormalities and crystal deposition were present from childhood, but sclerochoroidal calcification typically occurred after middle age.

CONCLUSIONS

Ocular abnormalities are uncommon in the genetic tubulopathies but may be helpful in recognizing the underlying genetic disease. The retinal expression and mouse phenotype data suggest that further ocular associations may become apparent with additional reports. Early identification may be necessary to monitor and treat visual complications.

Diagnosis and Management Strategies in Sclerochoroidal Calcification: A Systematic Review

Sclerochoroidal calcification (SCC) is a rare disease which is characterized by calcium deposition in the sclera. The choroid is secondarily involved. Typical localization is in the midperipheral region, outside the vascular arcades. SCC is mostly located in the superotemporal quadrant. Often times, the patients are referred with the diagnosis of an amelanotic tumor. SCC may be dystrophic or metastatic. Metastatic SCC lesions are associated with conditions altering calcium and phosphate metabolism including primary and secondary hyperparathyroidism, vitamin D intoxication, renal failure, hyperphosphatemia, and destructive bony lesions. SCC lesions have a characteristic appearance and appear as distinct, ill-defined, yellow-white, elevated scleral/choroidal masses funduscopically. The purpose of this literature review is to review the current knowledge on SCC, highlight the imaging features, and discuss the differential diagnosis as well as management options.

The Bartter-Gitelman Spectrum: Fifty Year Follow-up with Revision of Diagnosis after Whole Genome Sequencing

Bartter syndrome (BS) and Gitelman syndrome (GS) are renal tubular disorders affecting sodium, potassium, and chloride reabsorption. Clinical features include muscle cramps and weakness, in association with hypokalemia, hypochloremic metabolic alkalosis, and hyperreninemic hyperaldosteronism. Hypomagnesemia and hypocalciuria are typical of GS, while juxtaglomerular hyperplasia is characteristic of BS. GS is due to SLC12A3 variants, whereas BS is due to variants in SLC12A1, KCNJ1, CLCNKA, CLCNKB, BSND, MAGED2, or CASR. We had the opportunity to follow up one of the first reported cases of a salt-wasting tubulopathy, who based on clinical features was diagnosed with GS. The patient had presented at age 10 years with tetany precipitated by vomiting or diarrhea. She had hypokalemia, a hypochloremic metabolic alkalosis, hyponatremia, mild hypercalcemia, and normomagnesemia, and subsequently developed hypocalciuria and hypomagnesemia. A renal biopsy showed no evidence for juxtaglomerular hyperplasia. She developed chronic kidney failure at age 55 years, and ocular sclerochoroidal calcification, associated with BS and GS, at older than 65 years. Our aim was therefore to establish the genetic diagnosis in this patient using whole-genome sequencing (WGS). Leukocyte DNA was used for WGS analysis, and this revealed a homozygous c.226C > T (p.Arg76Ter) nonsense CLCNKB mutation, thereby establishing a diagnosis of BS type-3. WGS also identified 2 greater than 5-Mb regions of homozygosity that suggested likely mutational heterozygosity in her parents, who originated from a Greek island with fewer than 1500 inhabitants and may therefore have shared a common ancestor. Our results demonstrate the utility of WGS in establishing the correct diagnosis in renal tubular disorders with overlapping phenotypes.

Choroidal calcifications in two cases of aplasia cutis congenita and oculoectodermal syndrome

PURPOSE

To describe choroidal calcifications as an ophthalmic feature in aplasia cutis congenita (ACC) with oculoectodermal syndrome (OES).

OBSERVATIONS

Two cases of ACC/OES with characteristic echographic evidence of choroidal calcifications are described.

CONCLUSIONS AND IMPORTANCE

The ophthalmic manifestations of ACC/OES may be expanded to include choroidal calcifications. The presence of a choroidal calcification with B-scan ultrasound in a case suspicious for ACC/OES may facilitate a more timely diagnosis and inform future follow-up regimens to monitor ophthalmic and systemic manifestations of this disease.

Gitelman syndrome and ectopic calcification in the retina and joints

Gitelman syndrome is a rare inherited renal tubular disorder with features that resemble thiazide use, including a hypokalemic metabolic alkalosis, hypomagnesemia, hypocalciuria and a low or normal blood pressure, hyperreninemia and hyperaldosteronism. Treatment is primarily correction of the potassium and magnesium levels. The diagnosis is confirmed with genetic testing but Gitelman syndrome is often not suspected. However, the association with ectopic calcification in the retina, blood vessels and chondrocalcinosis in the joints is a useful pointer to this diagnosis. Bilateral symmetrical whitish deposits of calcium pyrophosphate are visible superotemporally on ophthalmoscopy and retinal photography but are actually located beneath the retina in the sclerochoroid. Optical coherence tomography is even more sensitive for their detection. These deposits increase in size with time, but the rate of progression slows with long-term correction of the hypomagnesemia. Calcification may be complicated by atrophy of the overlying retina and visual loss. The deposits often correlate with ectopic calcification in the aorta and coronary and cerebral vessels. Chondrocalcinosis occurs in the large joints such as the knees. Ectopic calcification in Gitelman syndrome indicates the need for more aggressive management of Mg levels. Calcification is much less common in Bartter syndrome, which itself is rarer and associated less often with hypomagnesemia.

Sclerochoroidal calcification as an incidental finding during oncological staging of a patient with parotid malignancy: A case report

INTRODUCTION

Incidental finding of mass lesion in the choroid represents a very challenging situation for the ophthalmologist. We describe a case of an incidental, computed tomography (CT)-hyperintense, choroidal lesion in a patient with parotid malignancy and renal failure, and how multimodal imaging helped us reaching the correct diagnosis.

CASE DESCRIPTION

A 63-year-old man with parotid gland malignancy was brought to our attention because preoperative staging CT showed a hyperintense choroidal lesion of the right eye. Fundus examination showed a yellow elevated lesion near the superior temporal branch retinal artery. Enhanced depth imaging optical coherence tomography (EDI-OCT), A- and B-scan ultrasonography, and Indocyanine Green Angiography (ICGA) allowed us to exclude a malignant lesion and to diagnose a sclerochoroidal calcification.

CONCLUSION

Multimodal imaging can guide the clinician to choose the appropriate therapeutic approach even in case of uncommon conditions like sclerochoroidal calcification.

Learning Physiology From Inherited Kidney Disorders

The identification of genes causing inherited kidney diseases yielded crucial insights in the molecular basis of disease and improved our understanding of physiological processes that operate in the kidney. Monogenic kidney disorders are caused by mutations in genes coding for a large variety of proteins including receptors, channels and transporters, enzymes, transcription factors, and structural components, operating in specialized cell types that perform highly regulated homeostatic functions. Common variants in some of these genes are also associated with complex traits, as evidenced by genome-wide association studies in the general population. In this review, we discuss how the molecular genetics of inherited disorders affecting different tubular segments of the nephron improved our understanding of various transport processes and of their involvement in homeostasis, while providing novel therapeutic targets. These include inherited disorders causing a dysfunction of the proximal tubule (renal Fanconi syndrome), with emphasis on epithelial differentiation and receptor-mediated endocytosis, or affecting the reabsorption of glucose, the handling of uric acid, and the reabsorption of sodium, calcium, and magnesium along the kidney tubule.

Gitelman Syndrome: A Rare Cause of Seizure Disorder and a Systematic Review

Gitelman syndrome is one of the few inherited causes of metabolic alkalosis due to salt losing tubulopathy. It is caused by tubular defects at the level of distal convoluted tubules, mimicking a thiazide-like tumor. It usually presents in late childhood or in teenage as nonspecific weakness, fatigability, polyuria, and polydipsia but very rarely with seizures. It is classically associated with hypokalemia, hypomagnesemia, hypocalciuria, hyperreninemia, and hyperaldosteronism. However, less frequently, it can present with normal magnesium levels. It is even rarer to find normomagnesemic patients of GS who develop seizures as the main complication since hypomagnesemia is considered the principal etiology of abnormal foci of seizure-related brain activity in GS cases. Interestingly, patients with GS are oftentimes diagnosed during pregnancy when the classic electrolyte pattern consistent with GS is noticed. Our case presents GS with normal serum magnesium in a patient, with seizures being the main clinical presentation. We also did a comprehensive literature review of 122 reported cases to show the prevalence of normal magnesium in GS cases and an overview of clinical and biochemical variability in GS. We suggest that further studies and in-depth analysis are required to understand the pathophysiology of seizures in GS patients with both normal and low magnesium levels.

Gitelman syndrome: consensus and guidance from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference

Gitelman syndrome (GS) is a rare, salt-losing tubulopathy characterized by hypokalemic metabolic alkalosis with hypomagnesemia and hypocalciuria. The disease is recessively inherited, caused by inactivating mutations in the SLC12A3 gene that encodes the thiazide-sensitive sodium-chloride cotransporter (NCC). GS is usually detected during adolescence or adulthood, either fortuitously or in association with mild or nonspecific symptoms or both. The disease is characterized by high phenotypic variability and a significant reduction in the quality of life, and it may be associated with severe manifestations. GS is usually managed by a liberal salt intake together with oral magnesium and potassium supplements. A general problem in rare diseases is the lack of high quality evidence to inform diagnosis, prognosis, and management. We report here on the current state of knowledge related to the diagnostic evaluation, follow-up, management, and treatment of GS; identify knowledge gaps; and propose a research agenda to substantiate a number of issues related to GS. This expert consensus statement aims to establish an initial framework to enable clinical auditing and thus improve quality control of care.

[Diagnostic imaging for sclerochoroidal calcifica-tion]

The article presents two clinical cases of sclerochoroidal calcification. This is a rare benign condition that usually does not display itself and is only occasionally diagnosed. It can also be accompanied by systemic disorder of mineral metabolism. The data obtained through medical imaging indicate partial destruction of the choroid at the site of the damage that causes secondary changes in the overlying retina.

Bilateral Idiopathic Sclerochoroidal Calcifications

Background:

Sclerochoroidal calcification (SCC) is a rare and benign condition found mostly in middle-aged and elderly Caucasian men, characterized by multiple yellow-white lesions seen most commonly in the temporal regions of the fundus. While they may be concerning for benign tumors, primary neoplasias or metastases, SCCs most commonly present as asymptomatic findings during routine ophthalmologic testing and have a very good prognosis as they rarely cause visual deficits.

Objective:

To report and describe the findings in a case of bilateral idiopathic sclerochoroidal calcifications.

Methods:

A retrospective case report.

Results:

Repeated ophthalmological exams, including fundoscopic examination, ultrasonography, optical coherence tomography and fluorescein angiography, were all consistent bilateral idiopathic sclerochoroidal calcifications.

Conclusion:

While most cases of idiopathic sclerochoroidal calcifications represent a benign ophthalmological condition, there are known associations with other systemic conditions, such as hyperthyroidism, hyperparathyroidism, Bartter’s syndrome and Gitelman’s syndrome. It is for this reason that these patients warrant a full systemic work-up in addition to careful ophthalmological monitoring.

Stones, bones, groans, thrones, and psychiatric overtones: Systemic associations of sclerochoroidal calcification

Sclerochoroidal calcification (SCC) is a frequent masquerader of choroidal melanoma with important systemic associations such as hyperparathyroidism and parathyroid adenoma. Herein, we describe a case of a 67-year-old male who presented with an amelanotic choroidal lesion in the right eye (OD) and a history of kidney stones. Ultrasonography showed the lesion to be flat and calcified OD. Incidentally, a subclinical calcified plaque was also found in the fellow eye. Optical coherence tomography showed an elevated suprachoroidal mass in a table mountain configuration OD and flat configuration left eye, consistent with type 4 and type 1 SCC. The patient was referred for metabolic testing to rule out the underlying electrolyte imbalance and was found to be normal.

Novel brain MRI abnormalities in Gitelman syndrome

Gitelman syndrome is an autosomal recessive renal tubular disorder characterized by hypokalemic metabolic alkalosis, hypomagnesemia and hypocalciuria. The syndrome is caused by a defective thiazide-sensitive sodium chloride co-transporter in the distal convoluted tubules of the kidneys. Gitelman syndrome could be confused with Bartter syndrome; the main differentiating feature is the presence of low urinary calcium excretion in the former. Descriptions of neuroradiological imaging findings associated with Gitelman syndrome are very scarce in the literature and include basal ganglia calcification, idiopathic intracranial hypertension and sclerochoroidal calcification. Cauda equina syndrome-like presentation has been reported, but without any corresponding imaging findings on lumbar spine MRI. We report a 13-year-old male with Gitelman syndrome who presented with altered mental status following a fall and scalp laceration and unremarkable brain CT, followed during hospitalization by somnolence and seizures. Metabolically the patient demonstrated hypokalemia and hypomagnesemia. MRI demonstrated features of encephalopathy including predominantly right-sided cerebral hemispheric signal abnormality and cytotoxic edema, with bilateral symmetric involvement of the thalami, midbrain tegmentum and tectum and cerebellar dentate nuclei. MRI after five months obtained during a later episode of encephalopathy showed resolution of the signal abnormalities with setting in of brain atrophy and also areas of newly developed cytotoxic edema in the left thalamus, bilateral dorsal midbrain and right greater than left dentate nuclei. The described abnormalities, either recurrent or in isolation, have not previously been published in patients with Gitelman syndrome. We believe that the findings are due to alteration of respiratory chain function secondary to the metabolic derangement and hence have a similar imaging appearance as encephalopathy related to mitochondrial cytopathy or metabolic encephalopathy.

Idiopathic sclerochoroidal calcification

PURPOSE

Sclerochoroidal calcification is a rare ocular condition characterized by multifocal, yellow-white elevated fundus lesions typically located in the superotemporal quadrant along the superior arcades. The pathology of calcification can be classified as dystrophic, metastatic, or idiopathic. Vision-threatening complications may arise, such as choroidal neovascular membrane and serous retinal detachment. The pathogenesis of sclerochoroidal calcification remains unclear.

CASE REPORT

A 72-year-old Caucasian male patient presented to the clinic for routine examination. Fundus evaluation revealed bilateral, multifocal, pale yellow elevated lesions in the superotemporal fundus. Ultrasonography showed a focal area of hyper-reflectivity located in the posterior retina of both eyes, and optical coherence tomography showed an intact retina overlying the elevated lesions in the choroid. Systemic evaluation for dystrophic and metastatic calcification was negative, and the patient was diagnosed with idiopathic sclerochoroidal calcification.

CONCLUSIONS

It is important to distinguish sclerochoroidal calcification from other conditions to prevent unnecessary intervention. Calcification of body tissues warrants a systemic evaluation, including screening for calcium and phosphorous levels, to rule out underlying systemic disease. If a biochemical abnormality is discovered, it can be appropriately treated with supplements. If calcification is deemed idiopathic, then annual dilated examinations are recommended to monitor the fundus lesions. Visual prognosis for sclerochoroidal classification is good, as the lesions are typically located away from the macula and foveal encroachment is rare.

Calcific constrictive pericarditis with refractory hypokalemia in a patient with Gitelman's syndrome

Calcific constrictive pericarditis can be idiopathic or associated with radiation therapy, surgery, infection, or autoimmune disorders. Gitelman's syndrome is a distal renal tubular defect involving the thiazide-sensitive luminal sodium chloride cotransporter and has been associated with nephrolithiasis and chondrocalcinosis. There has not been any case of calcific constrictive pericarditis reported so far in association with Gitelman's syndrome. We have reported a male patient with persistent hypokalemia and refractory ascites diagnosed with calcific constrictive pericarditis and Gitelman's syndrome.

Sclerochoroidal calcification: idiopathic or associated with systemic disease?

BACKGROUND

Idiopathic sclerochoroidal calcification is a rare disorder that may be confused with a malignant tumor. In most patients, its etiology is unknown. Some patients have associated systemic disorders or syndromes.

METHODS

We report the case history of a patient with hypercalcemia and extensive sclerochoroidal calcifications; furthermore, we evaluate a series of seven patients with sclerochoroidal calcification, investigating calcium-phosphorus metabolism and screening for primary renal tubular hypokalemic metabolic alkalosis syndromes.

RESULTS

One patient was diagnosed with bilateral sclerochoroidal calcification; she had primary hyperparathyroidism due to a parathyroid adenoma. None of the other seven patients met the criteria of primary renal tubular hypokalemic metabolic alkalosis syndromes or had significant problems of calcium-phosphorus metabolism. Nevertheless, two of them had a history of kidney stones, whereas two others had a history of arthritis.

CONCLUSION

For all patients with sclerochoroidal calcification, it is important to exclude primary renal tubular hypokalemic metabolic alkalosis syndromes such as Bartter and Gitelman syndromes, because these patients have a higher risk of cardiovascular morbidity especially during anesthesia.

Globe calcification in congenital toxoplasmosis

Various patterns of distribution of intracerebral calcification have been described in congenital toxoplasmosis. We report a case of congenital toxoplasmosis with a rare finding of calcification in the globe detected by CT scan that has not been described earlier.

Sclerochoroidal calcification associated with Gitelman syndrome and calcium pyrophosphate dihydrate deposition

Sclerochoroidal calcification is an uncommon condition. Metabolic evaluation and clinical examination are important to exclude associated systemic conditions such as the Bartter and Gitelman syndromes. It has been suggested that the lesions seen in sclerochoroidal calcification are calcium pyrophosphate dihydrate crystals. This report describes the first documented case in the UK of sclerochoroidal calcification associated with Gitelman syndrome and calcium pyrophosphate dihydrate deposition.

Idiopathic sclerochoroidal calcification

BACKGROUND

Idiopathic sclerochoroidal calcification (ISC) is an uncommon condition of calcium deposition at the level of the sclera and choroid of the posterior pole. With normal acuity and visual field, it typically manifests in asymptomatic older males. It can be diagnosed on clinical grounds, appearing as multiple geographic, yellowish, placoid-like lesions in the sclera and choroid, commonly found in the superotemporal arcade of the midperipheral fundus in both eyes. Ocular ultrasound and fluorescein angiography have classic results.

CASE REPORT

An 85-year-old white man came to us for routine examination. Best-corrected visual acuity was 20/40 O.D. and O.S. Dilated fundus examination revealed several midperipheral yellowish-white deposits with retinal pigment epithelium hyperpigmentation temporally in each eye. Ocular ultrasound revealed high reflectivity consistent with calcium. The lesions demonstrated mild hyperfluorescence in the late phase of fluorescein angiography. Laboratory testing was void of abnormal calcium or phosphorous metabolism, and a diagnosis of ISC was made.

CONCLUSION

Idiopathic sclerochoroidal calcification is a benign lesion of calcium deposition in the posterior pole, often discovered on routine examination. Although it is idiopathic, systemic evaluation is warranted to rule out dystrophic or metastatic calcification by various pathological conditions associated with abnormal calcium-phosphorus metabolism--most notably, hyperparathyroidism. Differential diagnoses include choroidal osteoma, melanoma, and metastatic carcinoma.

Hereditary disorders of potassium homeostasis

There has been a dramatic recent increase in the understanding of the renal epithelial transport systems with the identification, cloning and characterization of a large number of membrane transport proteins. The aim of this chapter is to integrate this body of knowledge with the understanding of the clinical disorders that accompany gain, loss or dysregulation of function of these transport systems. The specific focus is on the best-defined human clinical syndromes in which there are derangements in potassium (K(+)) homeostasis. The focus is on inherited syndromes, rather than on acquired syndromes due to tubular transport defects, and the therapeutic approaches address chronic derangements of K(+) homeostasis rather than acute interventions directed at life-threatening hyperkalaemia.

CME review: sclerochoroidal calcification: the 2001 Harold Gifford Lecture

Sclerochoroidal calcification is a recently recognized ocular condition that is characterized by typical geographic yellow-white fundus lesions that usually occur bilaterally in adults. It can clinically simulate a number of intraocular tumors like choroidal metastasis, choroidal melanoma, and choroidal osteoma. Clinical evaluation with ultrasonography, computed tomography, and some histopathologic studies have supported the fact the condition represents calcium deposition in the sclera and choroid. Early reports suggested that sclerochoroidal calcification was usually associated with hypercalcemic conditions such as hyperparathyroidism and pseudohypoparathyroidism. Subsequently, many patients with sclerochoroidal calcification have had no apparent systemic associations and have been classified as idiopathic. However, very recent studies have suggested that this ocular condition can also be associated with Gitelman syndrome or Bartter syndrome. These are autosomal recessive conditions of hypokalemic alkalosis associated with hypomagnesemia and deposition of calcium salts in various tissues. Ophthalmologists should be familiar with fundus features and systemic associations of sclerochoroidal calcification.

Renal genetic disorders related to K+ and Mg2+

The recent knowledge of the renal epithelial transport systems has exploded with the identification, cloning, and characterization of a large number of membrane transport proteins. The fundamental aspects of these transporters are beginning to emerge at the molecular level and are summarized in the accompanying contributions in this volume of the Annual Review of Physiology. The aim of my review is to integrate this body of knowledge with the understanding of the clinical disorders of human mineral homeostasis that accompany gain, loss, or dysregulation of function of these transport systems. The specific focus is on the best defined human clinical syndromes in which there are derangements in K(+) and Mg(2+) homeostasis.

Inherited primary renal tubular hypokalemic alkalosis: a review of Gitelman and Bartter syndromes

Inherited hypokalemic metabolic alkalosis, or Bartter syndrome, comprises several closely related disorders of renal tubular electrolyte transport. Recent advances in the field of molecular genetics have demonstrated that there are four genetically distinct abnormalities, which result from mutations in renal electrolyte transporters and channels. Neonatal Bartter syndrome affects neonates and is characterized by polyhydramnios, premature delivery, severe electrolyte derangements, growth retardation, and hypercalciuria leading to nephrocalcinosis. It may be caused by a mutation in the gene encoding the Na-K-2Cl cotransporter (NKCC2) or the outwardly rectifying potassium channel (ROMK), a regulator of NKCC2. Classic Bartter syndrome is due to a mutation in the gene encoding the chloride channel (CLCNKB), also a regulator of NKCC2, and typically presents in infancy or early childhood with failure to thrive. Nephrocalcinosis is typically absent despite hypercalciuria. The hypocalciuric, hypomagnesemic variant of Bartter syndrome (Gitelman syndrome), presents in early adulthood with predominantly musculoskeletal symptoms and is due to mutations in the gene encoding the Na-Cl cotransporter (NCCT). Even though our understanding of these disorders has been greatly advanced by these discoveries, the pathophysiology remains to be completely defined. Genotype-phenotype correlations among the four disorders are quite variable and continue to be studied. A comprehensive review of Bartter and Gitelman syndromes will be provided here.