Choroidal calcification in Bartter 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.

Latent Epigenetic Programs in Müller Glia Contribute to Stress, Injury, and Disease Response in the Retina

Previous studies have demonstrated the dynamic changes in chromatin structure during retinal development that correlate with changes in gene expression. However, a major limitation of those prior studies was the lack of cellular resolution. Here, we integrate single-cell (sc) RNA-seq and scATAC-seq with bulk retinal data sets to identify cell type-specific changes in the chromatin structure during development. Although most genes' promoter activity is strongly correlated with chromatin accessibility, we discovered several hundred genes that were transcriptionally silent but had accessible chromatin at their promoters. Most of those silent/accessible gene promoters were in the Müller glial cells. The Müller cells are radial glia of the retina and perform a variety of essential functions to maintain retinal homeostasis and respond to stress, injury, or disease. The silent/accessible genes in Müller glia are enriched in pathways related to inflammation, angiogenesis, and other types of cell-cell signaling and were rapidly activated when we tested 15 different physiologically relevant conditions to mimic retinal stress, injury, or disease in human and murine retinae. We refer to these as "pliancy genes" because they allow the Müller glia to rapidly change their gene expression and cellular state in response to different types of retinal insults. The Müller glial cell pliancy program is established during development, and we demonstrate that pliancy genes are necessary and sufficient for regulating inflammation in the murine retina in vivo. In zebrafish, Müller glia can de-differentiate and form retinal progenitor cells that replace lost neurons. The pro-inflammatory pliancy gene cascade is not activated in zebrafish Müller glia following injury, and we propose a model in which species-specific pliancy programs underly the differential response to retinal damage in species that can regenerate retinal neurons (zebrafish) versus those that cannot (humans and mice).

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.

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.

The long-term complications of the inherited tubulopathies: an adult perspective

The inherited tubulopathies are lifelong disorders and their clinical features and complications may present quite different challenges in adulthood from those in childhood. In this review we outline the pathophysiology and documented complications (including the late and unusual) of the monogenic tubulopathies from the perspective of the adult nephrologist.

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.

Sclerochoroidal calcification in a patient with classic Bartter's syndrome

PURPOSE

To report sclerochoroidal calcification in a patient with classic Bartter's syndrome.

DESIGN

Observational case report.

METHODS

A 42-year-old woman with a 26-year history of classic Bartter's syndrome was found to have bilateral fundus tumors. The patient presented initially with quivering lips and hand stiffness at age 6 years but was not diagnosed until age 16 years. Treatment included magnesium and potassium supplementation and Amiloride therapy.

RESULTS

On ocular examination, there were multifocal, yellow-white, geographic, solid choroidal lesions along the superior and inferior retinal vascular arcades in both eyes. Ultrasonography showed echogenic, placoid calcified lesions at the level of the sclera and choroid, consistent with bilateral sclerochoroidal calcification.

CONCLUSIONS

Sclerochoroidal calcification can be associated with classic Bartter's syndrome.

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.

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.

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.

Choroidal calcifications in patients with Gitelman's syndrome

Gitelman's syndrome is a renal tubular disorder characterized by a sodium and chloride reabsorption defect in distal tubular cells that determines hypokalemia, metabolic alkalosis, hypomagnesemia, and low calcium excretion. The presence of choroidal calcifications was sought in five patients with Gitelman's syndrome by ophthalmic examination, fluorescein angiography, indocyanine green angiography, and ocular ultrasonography. Calcifications observed in the choroid of two patients were shown by ultrasonography in both patients. Ophthalmic and fluorangiographic examinations detected this alteration in one of the two subjects. Chondrocalcinosis was found in one patient with choroidal calcifications. These findings suggest that precipitation of calcium salts can occur in the choroidal tissue of patients with Gitelman's syndrome. Deposits appeared to be well seen by ultrasonography because of their depth in ocular tissues. Sclerochoroidal calcifications may be favored by the low calcium excretion, which is associated with normal intestinal calcium absorption in patients with Gitelman's syndrome.