Brief report: autosomal dominant familial hypoparathyroidism, sensorineural deafness, and renal dysplasia

Identification and in vivo functional analysis of a novel missense mutation in GATA3 causing hypoparathyroidism, sensorineural deafness and renal dysplasia syndrome in a Chinese family

PURPOSE

Hypoparathyroidism, sensorineural deafness, and renal dysplasia (HDR) syndrome is a rare autosomal dominant genetic disease associated with mutations in the GATA3 gene, which encodes GATA3 that plays essential roles in vertebrate development. This study aimed to identify and report the pathogenic mutation in GATA3 in a Chinese family diagnosed with HDR syndrome and determine its functional impacts in vivo.

SUBJECTS AND METHODS

The clinical features of a 25-year-old male patient with HDR syndrome and his parents were collected. GATA3 gene exome sequencing and Sanger sequencing were performed on the proband and his family, respectively. Functional analyses of GATA3 were performed using bioinformatics tools and zebrafish assays to determine pathogenicity and phenotype spectrum.

RESULTS

A novel, heterozygous, missense mutation in exon 4 of the GATA3 gene, c.863 G > A, p.Cys288Tyr, in the proband and his mother who presented the complete HDR triad, was predicted to be deleterious by in silico tools. 3D structure modeling showed that the variant caused significant structural changes. In vivo studies using a zebrafish animal model revealed the deleterious impact of the variant on the gill buds, otoliths, and pronephros.

CONCLUSION

We identified a novel missense mutation, GATA3 p.Cys288Tyr, within a family with HDR syndrome and delineated it as a loss-of-function variant in vivo. This expands the spectrum of GATA3 mutations associated with HDR syndrome in the Chinese population and mimics HDR-related changes in vivo.

Diagnosing Hypoparathyroidism, Sensorineural Deafness, and Renal Dysplasia Syndrome and a Novel GATA3 Variant

Hypoparathyroidism (hypoPTH), sensorineural deafness, and renal dysplasia (HDR) syndrome is a rare autosomal dominant condition with approximately 200 cases published. HDR syndrome is caused by variants of GATA binding protein 3 gene (GATA3), which encodes a transcription factor, with multiple types of GATA3 variants reported. We present the case of a 76-year-old woman who was diagnosed with hypoPTH when she was aged 40 years and transferred care to our institution. Further history elucidated presence of deafness at age 1 year and chronic kidney disease with a left atrophic kidney diagnosed in her 60 seconds. Genetic testing identified a novel GATA3 missense variant of unknown significance (c.791G > A, p.Cys264Tyr). There was no family history of hypoPTH, deafness, or renal disease, which might indicate incomplete penetrance or de novo mutation. Advanced modeling of protein sequence and biophysical properties predicts abnormal protein function, suggesting possible pathogenicity. In addition, a likely pathogenic variant in the same amino acid was previously described in a patient with HDR, supporting the in silico prediction of pathogenicity in our patient's variant. Syndromic hypoPTH should be considered in patients even if presenting later in life with presumed chronic isolated conditions. Genetic testing can guide further disease screening and family testing when appropriate.

Bone morphogenetic protein signaling pathway- Ethanol interactions disrupt palate formation independent of gata3

Fetal Alcohol Spectrum Disorders (FASD) describes a wide array of neurological defects and craniofacial malformations, associated with ethanol teratogenicity. While there is growing evidence for a genetic component to FASD, little is known of the genes underlying these ethanol-induced defects. Along with timing and dosage, genetic predispositions may help explain the variability within FASD. From a screen for gene-ethanol interactions, we found that mutants for Bmp signaling components are ethanol-sensitive leading to defects in the zebrafish palate. Loss of Bmp signaling results in reductions in gata3 expression in the maxillary domain of the neural crest in the 1st pharyngeal arch, leading to palate defects while upregulation of human GATA3 rescues these defects. Here, we show that ethanol-treated Bmp mutants exhibit misshaped and/or broken trabeculae. Surprisingly, up regulation of GATA3 does not rescue ethanol-induced palate defects and gata3 expression was not altered in ethanol-treated Bmp mutants or dorsomorphin-treated larvae. Timing of ethanol sensitivity shows that Bmp mutants are ethanol sensitive from 10 to 18 hours post-fertilization (hpf), prior to Bmp's regulation of gata3 in palate formation. This is consistent with our previous work with dorsomorphin-dependent knock down of Bmp signaling from 10 to 18 hpf disrupting endoderm formation and subsequent jaw development. Overall, this suggests that ethanol disrupts Bmp-dependent palate development independent of and earlier than the role of gata3 in palate formation by disrupting epithelial development. Ultimately, these data demonstrate that zebrafish is a useful model to identify and characterize gene-ethanol interactions and this work will directly inform our understanding of FASD.

Bone Morphogenetic Protein signaling pathway - ethanol interactions disrupt palate formation independent of gata3

Fetal Alcohol Spectrum Disorders (FASD) describes a wide array of neurological defects and craniofacial malformations, associated with ethanol teratogenicity. While there is growing evidence for a genetic component to FASD, little is known of the genes underlying these ethanol-induced defects. Along with timing and dosage, genetic predispositions may help explain the variability within FASD. From a screen for gene-ethanol interactions, we found that mutants for Bmp signaling components are ethanol-sensitive leading to defects in the zebrafish palate. Loss of Bmp signaling results in reductions in gata3 expression in the maxillary domain of the neural crest in the 1st pharyngeal arch, leading to palate defects while upregulation of human GATA3 rescues these defects. Here, we show that ethanol-treated Bmp mutants exhibit misshaped and/or broken trabeculae. Surprisingly, up regulation of GATA3 does not rescue ethanol-induced palate defects and gata3 expression was not altered in ethanol-treated Bmp mutants or dorsomorphin-treated larvae. Timing of ethanol sensitivity shows that Bmp mutants are ethanol sensitive from 10-18 hours post-fertilization (hpf), prior to Bmp's regulation of gata3 in palate formation. This is consistent with our previous work with dorsomorphin-dependent knock down of Bmp signaling from 10-18 hpf disrupting endoderm formation and subsequent jaw development. Overall, this suggests that ethanol disrupts Bmp-dependent palate development independent of and earlier than the role of gata3 in palate formation by disrupting epithelial development. Ultimately, these data demonstrate that zebrafish is a useful model to identify and characterize gene-ethanol interactions and this work will directly inform our understanding of FASD.

Highlights

Bmp pathway mutants are ethanol sensitive resulting in palate defects. Ethanol disrupts Bmp-dependent palate development independent of gata3 . Timing of ethanol sensitivity suggests ethanol disrupts Bmp-dependent epithelial morphogenesis.

A novel frameshift variant of GATA3 (p.Ala17ProfsTer178) responsible for HDR syndrome in a Japanese family

HDR syndrome is an autosomal dominant disorder characterized by hypoparathyroidism (H), deafness (D), and renal dysplasia (R) caused by genetic variants of the GATA3 gene. We present the case of a 38-year-old Japanese man with HDR syndrome who exhibited hypoparathyroidism, sensorineural deafness, renal dysfunction, severe symptomatic hypocalcemia with Chvostek's and Trousseau's signs, and QT prolongation on electrocardiography. He had a family history of deafness and hypocalcemia. Genetic testing revealed a novel GATA3 gene variant at exon 2 (c.48delC), which induces a frameshift resulting in termination at codon 178, causing HDR syndrome. We summarized 45 Japanese cases of HDR syndrome with regard to the mode of onset (familial or sporadic) and the age at diagnosis. In addition, we summarized all previous cases of HDR syndrome with GATA3 gene variants. Mapping of previously reported genetic variants in HDR syndrome revealed that most missense variants were observed at exons 4 and 5 regions in the GATA3 gene. These two regions contain zinc finger domains, demonstrating their functional importance in GATA3 transcription. This review of literature provides a useful reference for diagnosing HDR syndrome and predicting the related future manifestations.

HDR syndrome: Large cohort and systematic review

HDR syndrome is a rare disease characterized by hypoparathyroidism, deafness, and renal dysplasia. An autosomal dominant disease caused by heterozygous pathogenic GATA3 variants, the penetrance of each associated condition is variable. Literature reviews have provided some answers, but many questions remain, in particular what the relationship is between genotype and phenotype. The current study examines 28 patients with HDR syndrome combined with an exhaustive review of the literature. Some conditions such as hearing loss are almost always present, while others described as rare initially, do not seem to be so rare after all (genital malformations and basal ganglia calcifications). By modeling pathogenic GATA3 variants found in HDR syndrome, we found that missense variations appear to always be located in the same area (close to the two Zinc Finger domain). We describe new pathogenic GATA3 variants, of which some seem to always be associated with certain conditions. Many audiograms were studied to establish a typical audiometric profile associated with a phenotype in HDR. As mentioned in the literature, hearing function should always be assessed as early as possible and follow up of patients with HDR syndrome should include monitoring of parathyroid function and vesicoureteral reflux in order to prevent complications.

HDR syndrome, detected in the neonatal period by newborn hearing screening

Hypoparathyroidism, deafness, and renal dysplasia (HDR) syndrome is an autosomal dominant disorder. Because HDR syndrome is caused by haploinsufficiency in GATA3, it exhibits variation in the onset and progression of hearing loss. In previous reports, the automated auditory brainstem response (AABR) was considered insufficient to detect sensorineural hearing loss caused by HDR syndrome. We report a case of HDR syndrome whose congenital hearing loss was detected by newborn hearing screening (NHS) using AABR. In this case, HDR syndrome was suspected due to hearing loss, hypocalcemia, and her family history. Genetic testing confirmed the diagnosis of HDR syndrome at 5 months of age. Because the phenotype of hearing loss due to HDR syndrome is variable and includes progressive hearing loss, these cases may not be detected by the HNS. However, most of the previous reports were published before the NHS became common and given the frequency of hearing loss complications in HDR syndrome. We consider that there is a reasonable number of HDR syndrome cases with abnormalities on the NHS. We believe that the NHS may also be useful for early detection of hearing loss due to HDR syndrome.

A novel GATA3 frameshift mutation causes hypoparathyroidism, sensorineural deafness, and renal dysplasia syndrome

Background

Hypoparathyroidism, sensorineural deafness, and renal dysplasia (HDR) syndrome (Barakat syndrome) is a rare autosomal dominant disorder caused by mutations in the gene encoding GATA3 on chromosome 10p14.

Method

Informed consent was obtained from a 38-year-old female patient. 5 mL of venous blood was collected and sent for whole-exome sequencing. GATA3 constructs of both wild-type and mutant were transfected into HEK-293 T cells. Three-dimensional modeling, luciferase-reporter gene test, western blotting and cellular immunofluorescence were used to evaluate the effect of the mutation.

Results

A novel frameshift mutation c. 677dup(p.Pro227AlafsTer77), named P227Afs, was found in GATA3. Three-dimensional modeling revealed that the mutation caused the loss of the dual zinc finger structures 1 and 2 (ZNF1 and ZNF2) of the synthesized protein. Expression of wild-type GATA3 produced a six-fold increase in luciferase activity when compared with pcDNA3.1 vector only (P < 0.001), whereas the P227Afs mutant showed no increase. The mutation significantly reduced the transcriptional activity of GATA3. Immunofluorescence and western blotting analyses demonstrated that the mutation changed the nuclear location of GATA3 and caused difficulty in nuclearization.

Conclusion

A novel heterozygous frameshift mutation in GATA3 was identified and showed to result in difficult nuclearization, and a dominant-negative effect on the wild-type.

Clinical and molecular characteristics of two Italian kindreds with hypoparathyroidism, deafness and renal dysplasia (HDR) syndrome

PURPOSE

Hypoparathyroidism, deafness, and renal dysplasia (HDR) syndrome, also known as Barakat syndrome, is a rare autosomal dominant disease characterized by the triad of hypoparathyroidism, deafness, and renal abnormalities. The disorder is caused by the haploinsufficiency of the zinc finger transcription factor GATA3 and exhibits a great clinical variability with an age-dependent penetrance of each feature. We report two unrelated kindreds whose probands were referred to our outpatient clinic for further evaluation of hypoparathyroidism.

METHODS

The proband of family 1, a 17-year-old boy, was referred for severe hypocalcemia (5.9 mg/dL) incidentally detected at routine blood tests. Abdomen ultrasound showed bilateral renal cysts. The audiometric evaluation revealed the presence of bilateral moderate hearing loss although the patient could communicate without any problem. Conversely, the proband of family 2, a 19-year-old man, had severe symptomatic hypocalcemia complicated by epileptic seizure at the age of 14 years; his past medical history was remarkable for right nephrectomy at the age of 4 months due to multicystic renal disease and bilateral hearing loss diagnosed at the age of 18 years.

RESULTS

Based on clinical, biochemical, and radiologic data, HDR syndrome was suspected and genetic analysis of the GATA3 gene revealed the presence of two pathogenetic variants in exon 3, c.404dupC and c.431dupG, in the proband of family 1 and 2, respectively.

CONCLUSION

HDR syndrome is a rare cause of hypoparathyroidism and must be excluded in all patients with apparently idiopathic hypoparathyroidism. A correct diagnosis is of great importance for early detection of other HDR-related features and genetic counseling.

Shared features in ear and kidney development - implications for oto-renal syndromes

The association between ear and kidney anomalies has long been recognized. However, little is known about the underlying mechanisms. In the last two decades, embryonic development of the inner ear and kidney has been studied extensively. Here, we describe the developmental pathways shared between both organs with particular emphasis on the genes that regulate signalling cross talk and the specification of progenitor cells and specialised cell types. We relate this to the clinical features of oto-renal syndromes and explore links to developmental mechanisms.

Ocular manifestations of congenital anomalies of the kidney and urinary tract (CAKUT)

Congenital anomalies of the kidney and urinary tract (CAKUT) are among the most common birth defects worldwide and a major cause of kidney failure in children. Extra-renal manifestations are also common. This study reviewed diseases associated with the Genomics England CAKUT-associated gene panel for ocular anomalies. In addition, each gene was examined for expression in the human retina and an ocular phenotype in mouse models using the Human Protein Atlas and Mouse Genome Informatics databases, respectively. Thirty-four (54%) of the 63 CAKUT-associated genes (55 'green' and 8 'amber') had a reported ocular phenotype. Five of the 6 most common CAKUT-associated genes (PAX2, EYA1, SALL1, GATA3, PBX1) that represent 30% of all diagnoses had ocular features. The ocular abnormalities found with most CAKUT-associated genes and with five of the six commonest were coloboma, microphthalmia, optic disc anomalies, refraction errors (astigmatism, myopia, and hypermetropia), and cataract. Seven of the CAKUT-associated genes studied (11%) had no reported ocular features but were expressed in the human retina or had an ocular phenotype in a mouse model, which suggested further possibly-unrecognised abnormalities. About one third of CAKUT-associated genes (18, 29%) had no ocular associations and were not expressed in the retina, and the corresponding mouse models had no ocular phenotype. Ocular abnormalities in individuals with CAKUT suggest a genetic basis for the disease and sometimes indicate the affected gene. Individuals with CAKUT often have ocular abnormalities and may require an ophthalmic review, monitoring, and treatment to preserve vision.

A Novel Mutation in GATA3 Gene in a Case of Hypoparathyroidism, Deafness, and Renal Dysplasia Syndrome

A 39-year-old male was incidentally detected to have hypertension and chronic kidney disease (CKD) with left solitary functioning kidney in 2017. He has bilateral sensorineural hearing loss since adolescence. He was initially suspected to have adynamic bone disease in view of low parathyroid hormone levels and was started on teriparatide injections and calcium supplements. Despite all these measures, he had persistent hypocalcemia and low parathyroid hormone levels. Hence, Hypoparathyroidism, Deafness, and Renal dysplasia (HDR) syndrome was suspected, and the patient was evaluated for the same. Genetic analysis revealed the presence of a de novo and a novel frameshift mutation in GATA-binding protein 3 (GATA3) gene on chromosome 10p. To the best of our knowledge, this is the first case report of HDR syndrome being diagnosed by genetic analysis in India.

Hypoparathyroidism, Sensorineural Deafness, and Renal Disease Syndrome Presenting With Febrile Seizures and Hypocalcemia

HDR syndrome is a rare genetic disorder caused by mutations in the GATA3 gene and characterized by hypoparathyroidism, sensorineural deafness, and renal disease. Here, we report case of a 9-month-old male with history of hydronephrosis and sensorineural deafness who presented with febrile seizures. He was found to have hypocalcemia and inappropriately normal parathyroid hormone. His neurologic and infectious workup were negative. Genetic testing revealed a nonsense mutation in the GATA3 gene, consistent with HDR syndrome. Hypocalcemia was responsive to calcium carbonate and calcitriol treatment. This case highlights hypocalcemia caused by hypoparathyroidism as a potential etiology of seizures. When hypoparathyroidism is detected with either hearing loss or renal disease, HDR syndrome should be considered, and other features of the syndrome should be investigated.

The centrosomal protein 83 (CEP83) regulates human pluripotent stem cell differentiation toward the kidney lineage

During embryonic development, the mesoderm undergoes patterning into diverse lineages including axial, paraxial, and lateral plate mesoderm (LPM). Within the LPM, the so-called intermediate mesoderm (IM) forms kidney and urogenital tract progenitor cells, while the remaining LPM forms cardiovascular, hematopoietic, mesothelial, and additional progenitor cells. The signals that regulate these early lineage decisions are incompletely understood. Here, we found that the centrosomal protein 83 (CEP83), a centriolar component necessary for primary cilia formation and mutated in pediatric kidney disease, influences the differentiation of human-induced pluripotent stem cells (hiPSCs) toward IM. We induced inactivating deletions of CEP83 in hiPSCs and applied a 7-day in vitro protocol of IM kidney progenitor differentiation, based on timed application of WNT and FGF agonists. We characterized induced mesodermal cell populations using single-cell and bulk transcriptomics and tested their ability to form kidney structures in subsequent organoid culture. While hiPSCs with homozygous CEP83 inactivation were normal regarding morphology and transcriptome, their induced differentiation into IM progenitor cells was perturbed. Mesodermal cells induced after 7 days of monolayer culture of CEP83-deficient hiPCS exhibited absent or elongated primary cilia, displayed decreased expression of critical IM genes (PAX8, EYA1, HOXB7), and an aberrant induction of LPM markers (e.g. FOXF1, FOXF2, FENDRR, HAND1, HAND2). Upon subsequent organoid culture, wildtype cells differentiated to form kidney tubules and glomerular-like structures, whereas CEP83-deficient cells failed to generate kidney cell types, instead upregulating cardiomyocyte, vascular, and more general LPM progenitor markers. Our data suggest that CEP83 regulates the balance of IM and LPM formation from human pluripotent stem cells, identifying a potential link between centriolar or ciliary function and mesodermal lineage induction.

Variation in phenotypes from a Bmp-Gata3 genetic pathway is modulated by Shh signaling

We sought to understand how perturbation of signaling pathways and their targets generates variable phenotypes. In humans, GATA3 associates with highly variable defects, such as HDR syndrome, microsomia and choanal atresia. We previously characterized a zebrafish point mutation in gata3 with highly variable craniofacial defects to the posterior palate. This variability could be due to residual Gata3 function, however, we observe the same phenotypic variability in gata3 null mutants. Using hsp:GATA3-GFP transgenics, we demonstrate that Gata3 function is required between 24 and 30 hpf. At this time maxillary neural crest cells fated to generate the palate express gata3. Transplantation experiments show that neural crest cells require Gata3 function for palatal development. Via a candidate approach, we determined if Bmp signaling was upstream of gata3 and if this pathway explained the mutant's phenotypic variation. Using BRE:d2EGFP transgenics, we demonstrate that maxillary neural crest cells are Bmp responsive by 24 hpf. We find that gata3 expression in maxillary neural crest requires Bmp signaling and that blocking Bmp signaling, in hsp:DN-Bmpr1a-GFP embryos, can phenocopy gata3 mutants. Palatal defects are rescued in hsp:DN-Bmpr1a-GFP;hsp:GATA3-GFP double transgenic embryos, collectively demonstrating that gata3 is downstream of Bmp signaling. However, Bmp attenuation does not alter phenotypic variability in gata3 loss-of-function embryos, implicating a different pathway. Due to phenotypes observed in hypomorphic shha mutants, the Sonic Hedgehog (Shh) pathway was a promising candidate for this pathway. Small molecule activators and inhibitors of the Shh pathway lessen and exacerbate, respectively, the phenotypic severity of gata3 mutants. Importantly, inhibition of Shh can cause gata3 haploinsufficiency, as observed in humans. We find that gata3 mutants in a less expressive genetic background have a compensatory upregulation of Shh signaling. These results demonstrate that the level of Shh signaling can modulate the phenotypes observed in gata3 mutants.

Case Report: Clinical Description of a Patient Carrying a 12.48 Mb Microdeletion Involving the 10p13-15.3 Region

Partial deletion of 10p chromosome is a rare chromosomal aberration. Submicroscopic deletion of 10p15.3 is mainly related to cognitive deficits, speech disorders, motor delay, and hypotonia with the deleted region ranging from 0.15 to 4 Mb. The clinical phenotype is mainly determined by the ZMYND11 and DIP2C genes. Here, we report a rare case of feeding difficulties, hypocalcemia, and psychomotor retardation. Our patient has a 12.48 Mb deletion in 10p15.3-10p13, which is the second case of large 10p deletion among reported cases thus far.

A case of hypoparathyroidism, deafness, and renal dysplasia (HDR) syndrome with a novel frameshift variant in GATA3, p.W10Cfs40, lacks kidney malformation

Autosomal dominant hypoparathyroidism, deafness, and renal dysplasia (HDR) syndrome are typically diagnosed by manifestations of the three features with a positive family history. Our case carried a de novo variant in causative gene, GATA3, but presenting no renal dysplasia or family history. The phenotypic heterogeneity raises a caution for diagnosis.

Hypoparathyroidism, deafness, and renal dysplasia syndrome: 20 Years after the identification of the first GATA3 mutations

The hypoparathyroidism, deafness, and renal dysplasia (HDR) syndrome is an autosomal dominant disorder caused by heterozygous mutations of the GATA3 gene. In the last 20 years, since the identification of the genetic cause of the HDR syndrome, GATA3 mutations have been reported in 124 families (177 patients). The clinical aspects and molecular genetics of the HDR syndrome are reviewed here together with the reported mutations and phenotypes. Reported mutations consist of 40% frameshift deletions or insertions, 23% missense mutations, 14% nonsense mutations, 6% splice-site mutations, 1% in-frame deletions or insertions, 15% whole-gene deletions, and 1% whole-gene duplication. Missense mutations were found to cluster in the regions encoding the two GATA3 zinc-finger domains. Patients showed great clinical variability and the penetrance of each HDR defect increased with age. The most frequently observed abnormality was deafness (93%), followed by hypoparathyroidism (87%) and renal defects (61%). The mean age of diagnosis of HDR was 15.3, 7.5, and 14.0 years, respectively. However, patients with whole-gene deletions and protein-truncating mutations were diagnosed earlier than patients with missense mutations.

Hypoparathyroidism

BACKGROUND

Hypoparathyroidism is a rare endocrine disorder characterized by hypocalcemia and low or undetectable levels of parathyroid hormone.

METHODS

This review is an evidence-based summary of hypoparathyroidism in terms of relevant pathophysiological, clinical, and therapeutic concepts.

RESULTS

Many clinical manifestations of hypoparathyroidism are due to the lack of the physiological actions of parathyroid hormone on its 2 major target organs: the skeleton and the kidney. The skeleton is inactive, accruing bone without remodeling it. The kidneys lose the calcium-conserving actions of parathyroid hormone and, thus, excrete a greater fraction of calcium. Biochemical manifestations, besides hypocalcemia and low or undetectable levels of parathyroid hormone, include hyperphosphatemia and low levels of 1,25-dihydroxyvitamin D. Calcifications in the kidney, brain, and other soft tissues are common. Removal of, or damage to, the parathyroid glands at the time of anterior neck surgery is, by far, the most likely etiology. Autoimmune destruction of the parathyroid glands and other genetic causes represent most of the other etiologies. Conventional treatment with calcium and active vitamin D can maintain the serum calcium level but high doses may be required, adding to the risk of long-term soft tissue calcifications. The advent of replacement therapy with recombinant human PTH(1-84) represents a major step in the therapeutics of this disease.

CONCLUSIONS

Advances in our knowledge of hypoparathyroidism have led to greater understanding of the disease itself and our approach to it.

Hypoparathyroidism, Sensorineural deafness and renal disease (Barakat syndrome) caused by a reduced gene dosage in GATA3: a case report and review of literature

BACKGROUND

Barakat syndrome is an autosomal dominant rare genetic disease caused by haploinsufficiency of the GATA binding protein 3 (GATA3) gene. It is also known as HDR syndrome, and is characterized by varying degrees of hypoparathyroidism, sensorineural deafness and renal disease. This is the first report of a heterozygous GATA3 whole gene deletion causing HDR syndrome in a Sri Lankan family.

CASE PRESENTATION

A 13-year-old boy with an acute febrile illness, hypocalcaemia and bilateral carpopedal spasm was referred for evaluation. A past medical history of treatment for persistent hypocalcaemic symptoms since the age of 7 months was obtained. Biochemical investigations showed persistent low serum corrected calcium levels with hyperphosphataemia, hypomagnesaemia, low parathyroid hormone levels, hypercalciuria, and low total 25-hydroxy vitamin D levels. His renal functions and renal sonography were normal. Audiometry showed bilateral moderate to severe sensorineural hearing loss. On screening, his mother was also found to have asymptomatic hypocalcaemia, hypomagnesaemia, hyperphosphataemia, hypercalciuria and low total 25-hydroxy vitamin D levels. She had impaired renal functions and chronic parenchymal changes in the renal scan. Audiometry showed bilateral profound sensorineural hearing loss. Genetic analysis using multiplex-ligation dependent probe amplification showed a reduced gene dosage for GATA3 that is consistent with a heterozygous whole gene deletion in both the child and mother.

CONCLUSIONS

This report demonstrates the wide intra-familial phenotypic variability observed in HDR syndrome and adds further to the existing scientific literature on the genotype-phenotype correlation of this syndrome. It highlights the need for HDR syndrome to be considered in the differential diagnosis of persistent hypocalcaemia with sensorineural deafness and/or renal involvement, and for appropriate genetic evaluation to be done to confirm the diagnosis.

Congenital Anomalies of the Kidney and Urinary Tract: A Clinical Review

Purpose of review

This review highlights the most common congenital anomalies of the kidney and urinary tract (CAKUT) that are encountered in pediatric practices. CAKUT are the most common cause of prenatally diagnosed developmental malformations and encompass a spectrum of disorders impacting lower urinary tract development as well as kidney development and function. In pediatric and adolescent populations, developmental abnormalities are the leading cause of end-stage kidney disease. The goal of this review is to provide pediatric providers a framework for appropriate clinical management as well as highlight when referral to subspecialty care is needed.

Recent findings

While the exact etiologies of CAKUT are not completely defined, new evidence demonstrates that genetic and molecular changes impact embryonic kidney and urinary tract development. As a result, phenotypes and clinical outcomes may be affected.

Summary

Because pediatric providers provide front-line care to children and adolescents with developmental kidney and urinary tract anomalies, updated knowledge of CAKUT pathogenesis, embryology, clinical management, and patient outcomes is needed. This manuscript reviews CAKUT etiologies and essential diagnostic, prognostic, and management strategies.

HDR Syndrome Accompanying Type 1 Diabetes Mellitus and Hypopituitarism

HDR (Hypoparathyroidism, Deafness, and Renal Dysplasia) syndrome is an autosomal dominant disorder characterized by the triad of hypoparathyroidism, sensorineural deafness, and renal disease. Approximately 65% of patients with HDR syndrome have all three of these features, while others have different combinations of these features. We aimed to present a case with primary hypoparathyroidism, hearing loss, and nondiabetic chronic kidney disease and diagnosed as HDR syndrome while being followed up for type 1 diabetes mellitus and hypopituitarism.

Genetic Disorders of Parathyroid Development and Function

Hypoparathyroidism is characterized by hypocalcemia and hyperphosphatemia and is due to insufficient levels of circulating parathyroid hormone. Hypoparathyroidism may be an isolated condition or a component of a complex syndrome. Although genetic disorders are not the most common cause of hypoparathyroidism, molecular analyses have identified a growing number of genes that when defective result in impaired formation of the parathyroid glands, disordered synthesis or secretion of parathyroid hormone, or postnatal destruction of the parathyroid glands.

Familial congenital choanal atresia with GATA3 associated hypoparathyroidism-deafness-renal dysplasia syndrome unidentified on auditory brainstem response

Hypoparathyroidism-deafness-renal dysplasia (HDR) syndrome is a rare autosomal dominant disorder primarily caused by GATA3 haploinsufficiency and is challenging to diagnose in early childhood. We report a Japanese family with HDR syndrome and congenital choanal atresia. The 6-year-old female proband was diagnosed with epilepsy at the age of three. Under carbamazepine monotherapy, the patient presented hypoparathyroidism accompanied by severe hypocalcemia. Subsequently, renal ultrasound analysis revealed bilateral multicystic dysplastic kidneys. Because she had difficulty hearing, we sequenced GATA3 and determined that she had a c.708_709insC (p.Ser237Glnfs*66) allelic variant in exon 3. As a result, we found a family of this disease. Each family member, including her grandfather, mother, and two siblings, had HDR syndrome of varying clinical penetrance. We found a craniofacial anomaly, congenital choanal atresia, which was inherited as an autosomal dominant trait. Hypocalcemia coupled with vitamin D deficiency, triggered by carbamazepine treatment, ultimately revealed the proband's childhood- onset HDR syndrome. Pure-tone audiometry revealed different severities of deafness as well as the progression of sensory hearing loss. However, auditory brainstem response for hearing screening is probably insufficient for ascertaining HDR syndrome in the early stages of life. We presented new clinical clues to diagnose the HDR syndrome.

A rare case of deafness and renal abnormalities in HDR syndrome caused by a de novo mutation in the GATA3 gene

HDR syndrome is a rare autosomal dominant disorder caused by mutations in the GATA3 gene and characterized by hypoparathyroidism, sensorineural deafness and renal abnormalities. Here we report a Brazilian family, from which the proband, his mother and his grandfather were diagnosed with bilateral sensorineural hearing loss. Molecular screening of the GJB2, GJB6 and MTRNR1 genes in the proband showed no alterations; however, whole exome sequencing detected a heterozygous mutation, c.1099C > T (p.Arg367*), in the GATA3 gene. Segregation analyses showed that the mother also had the mutation, but not the grandparents, hence indicating a different hearing impairment type for the grandfather. Paternity test of the mother of the proband confirmed that she has a de novo mutation. Furthermore, HDR syndrome was confirmed with new clinical evaluations showing right kidney agenesis in the proband. This is the first study reporting only deafness and renal abnormalities as symptoms of the p.Arg367* mutation in the GATA3 gene, and also the sixth HDR syndrome case in the world, and the first on the American continent. Together with other reported cases, this study highlights the variability of HDR syndrome symptoms in individuals with the p.Arg367* mutation, emphasizing the importance of molecular analyses for correct diagnosis.

Barakat syndrome revisited

Barakat syndrome also known as HDR syndrome (Online Mendelian Inheritance in Man [OMIM] 146255), was first described by Barakat et al. in . It is a rare genetic disorder characterized by the triad of hypoparathyroidism "H," sensorineural deafness "D," and renal disease "R." The defect is caused by deletions in chromosome 10p14 or mutations in the GATA3 gene. Although the syndrome has been phenotypically defined by this triad the literature identifies cases with different components with, or without GATA3 defects making the definition of the syndrome confusing. We analyzed 180 cases and attempted to define the phenotype of the syndrome and suggest guidelines for diagnosis. We suggest that the diagnosis could be confirmed in patients who have all three components, and in those who have two components with a positive family history. GATA3 testing is optional to establish the diagnosis in these patients. The syndrome should be considered in patients with isolated "D" where other causes of "D" have been excluded and those with isolated "R," especially if there is family history of any of these components. In these instances, confirmatory GATA3 testing is indicated to confirm the diagnosis. In patients with nonsurgical "H," where "D" and "R" have been conclusively ruled out GATA3 studies are not needed as none of these patients were shown to be GATA3 haploinsufficient. Only 64.4% of patients in our review had "HDR." Some findings might have not been recognized or may could have appeared later in life, but it is evident that this syndrome is genotypically heterogeneous.

Lung squamous cell carcinoma associated with hypoparathyroidism with sensorineural deafness and renal dysplasia syndrome: a case report

Hypoparathyroidism with sensorineural deafness and renal dysplasia (HDR) syndrome is an autosomal dominant condition caused by mutations of the gene encoding the dual zinc-finger transcription factor, GATA3. A previous study identified some patients with GATA3 gene variants and breast cancer, suggesting that GATA3 variants may contribute to tumorigenesis in estrogen receptor 1-positive breast tumors; however, these patients did not have HDR syndrome. A 32-year-old nonsmoking Japanese woman was histologically diagnosed with lung squamous cell carcinoma associated with HDR syndrome and a c.C952T>C (p.C318R) germline mutation in GATA3. This is the first report describing cancer in a patient with HDR syndrome. Our data indicates that GATA3 mutations may be a potential therapeutic target for lung cancer.

Clinical and mutational spectrum of hypoparathyroidism, deafness and renal dysplasia syndrome

Background

Hypoparathyroidism, deafness and renal dysplasia (HDR) syndrome is a rare autosomal dominant disorder, secondary to mutations in the GATA-3 gene. Due to its wide range of penetrance and expressivity, the disease may not always be recognized. We herein describe clinical and genetic features of patients with HDR syndrome, highlighting diagnostic clues.

Methods

Medical records of eight patients from five unrelated families exhibiting GATA-3 mutations were reviewed retrospectively, in conjunction with all previously reported cases.

Results

HDR syndrome was diagnosed in eight patients between the ages of 18 and 60 years. Sensorineural deafness was consistently diagnosed, ranging from clinical hearing loss since infancy in seven patients to deafness detected only by audiometry in adulthood in one single patient. Hypoparathyroidism was present in six patients (with hypocalcaemia and inaugural seizures in two out of six). Renal abnormalities observed in six patients were diverse and of dysplastic nature. Three patients displayed nephrotic-range proteinuria and reached end-stage renal disease (ESRD) between the ages of 19 and 61 years, whilst lesions of focal and segmental glomerulosclerosis were histologically demonstrated in one of them. Interestingly, phenotype severity differed significantly between a mother and son within one family. Five new mutations of GATA-3 were identified, including three missense mutations affecting zinc finger motifs [NM_001002295.1: c.856A>G (p.N286D) and c.1017C>G (p.C339W)] or the conserved linker region [c.896G>A (p.R299G)], and two splicing mutations (c.924+4_924+19del and c.1051-2A>G). Review of 115 previously reported cases of GATA-3 mutations showed hypoparathyroidism and deafness in 95% of patients, and renal abnormalities in only 60%. Overall, 10% of patients had reached ESRD.

Conclusions

We herein expand the clinical and mutational spectrum of HDR syndrome, illustrating considerable inter- and intrafamilial phenotypic variability. Diagnosis of HDR should be considered in any patient with hypoparathyroidism and deafness, whether associated with renal abnormalities or not. HDR diagnosis is established through identification of a mutation in the GATA-3 gene.

Hypoparathyroidism

Hypoparathyroidism is a disease characterized by inadequately low circulating concentrations of parathyroid hormone (PTH) resulting in low calcium levels and increased phosphate levels in the blood. Symptoms of the disease result from increased neuromuscular irritability caused by hypocalcaemia and include tingling, muscle cramps and seizures. The most common cause of the disease is inadvertent removal of, or injury to, the parathyroid glands during neck surgery, followed by genetic, idiopathic and autoimmune aetiologies. Conventional treatment includes activated vitamin D and/or calcium supplements, but this treatment does not fully replace the functions of PTH and can lead to short-term problems (such as hypocalcaemia, hypercalcaemia and increased urinary calcium excretion) and long-term complications (which include nephrocalcinosis, kidney stones and brain calcifications). PTH replacement has emerged as a new treatment option. Clinical trials using human PTH(1-34) and PTH(1-84) showed that this treatment was safe and effective in studies lasting up to 6 years. Recombinant human PTH(1-84) has been approved in the United States and Europe for the management of hypoparathyroidism; however, its effect on long-term complications is still being evaluated. Clinical practice guidelines, which describe the consensus of experts in the field, have been published and recognize the need for more research to optimize care. In this Primer, we summarize current knowledge of the prevalence, pathophysiology, clinical presentation and management of hypoparathyroidism.

Unusual Proliferative Glomerulonephritis in a Patient Diagnosed to Have Hypoparathyroidism, Sensorineural Deafness, and Renal Dysplasia (HDR) Syndrome with a Novel Mutation in the GATA3 Gene

Hypoparathyroidism, sensorineural deafness, and renal dysplasia (HDR) syndrome is a rare autosomal dominant disease caused by GATA3 mutations. Although several cases with variable renal features have been reported, the presence of histological changes within the glomeruli in adult patients is unclear. We herein report an adult case of HDR syndrome with a novel p.C288W (TGC>TGG) missense mutation in GATA3. His renal histology showed a membranoproliferative glomerulonephritis-like glomerular lesion. Additional renal histological analyses of HDR syndrome patients will be needed to clarify the role of GATA3 in both the developing and adult kidney.

Cellular and Molecular Underpinnings of Neuronal Assembly in the Central Auditory System during Mouse Development

During development, the organization of the auditory system into distinct functional subcircuits depends on the spatially and temporally ordered sequence of neuronal specification, differentiation, migration and connectivity. Regional patterning along the antero-posterior axis and neuronal subtype specification along the dorso-ventral axis intersect to determine proper neuronal fate and assembly of rhombomere-specific auditory subcircuits. By taking advantage of the increasing number of transgenic mouse lines, recent studies have expanded the knowledge of developmental mechanisms involved in the formation and refinement of the auditory system. Here, we summarize several findings dealing with the molecular and cellular mechanisms that underlie the assembly of central auditory subcircuits during mouse development, focusing primarily on the rhombomeric and dorso-ventral origin of auditory nuclei and their associated molecular genetic pathways.

A novel loss-of-function mutation of GATA3 (p.R299Q) in a Japanese family with Hypoparathyroidism, Deafness, and Renal Dysplasia (HDR) syndrome

BACKGROUND

Hypoparathyroidism, deafness, and renal dysplasia (HDR) syndrome is a rare autosomal dominant disorder caused by mutations in the zinc finger transcription factor gene, GATA3. GATA3 has 2 zinc finger domains, which play an important role in the increase in target gene transcription activity.

CASE PRESENTATION

A 50-year-old woman and her 27-year-old daughter were followed up because of hypoparathyroidism. They had bilateral sensorineural deafness. Abdominal computed tomography scanning revealed renal dysplasia in the mother, but no renal anomaly in the daughter. Direct sequencing of GATA3 gene revealed a novel heterozygous missense mutation at codon 299 (p.R299Q) in exon 4. This mutation is located at the junction between the 2 zinc fingers. The structure prediction showed that it caused a conformation change in this junction area, affecting the spatial position of the zinc fingers. Additionally, a more marked conformation change was observed in the N-terminal zinc finger region compared to that in the C-terminal region. Functional analysis of this mutant protein using an in vitro luciferase reporter assay system confirmed that the mutation abolished the enhancing effects of wild-type GATA3 on the promoter activity of the consensus GATA responsive element and that of human PTH gene.

CONCLUSION

We identified a novel R299Q mutation in GATA3 in a Japanese family with HDR syndrome. We confirmed that R299Q is a loss-of-function mutation, due to the extensive conformational change in the zinc fingers of GATA3.

Identification of a novel de novo GATA3 mutation in a patient with HDR syndrome

We describe the case of a 21-year-old male with hypocalcaemia, hyperphosphataemia, recurrent limb twitch, deafness, proteinuria, increased serum creatinine and urea nitrogen levels, and shrinkage of both kidneys. Brain computed tomography showed intracranial calcifications. The patient was diagnosed with hypoparathyroidism, sensorineural deafness and renal dysplasia (HDR) syndrome. DNA sequence analysis of the GATA3 gene showed a novel de novo mutation, c. 529dupC (p. Arg177profs*126), in exon 2, resulting in a frameshift mutation with a premature stop codon after a new 126 amino acid sequence. We provide further evidence that HDR syndrome is caused by haploinsufficiency of GATA3.

Transactivation of human osteoprotegerin promoter by GATA-3

Osteoprotegerin (OPG) is a key regulator of bone remodeling. Mutations in OPG are involved in a variety of human diseases. We have shown that cochlear spiral ganglion cells secrete OPG at high levels and lack of OPG causes sensorineural hearing loss in addition to the previously described conductive hearing loss. In order to study the regulation of OPG expression, we conducted a database search on regulatory elements in the promoter region of the OPG gene, and identified two potential GATA-3 binding sites. Using luciferase assays and site directed mutagenesis, we demonstrate that these two elements are GATA-3 responsive and support GATA-3 transactivation in human HEK and HeLa cells. The expression of wild type GATA-3 activated OPG mRNA and protein expression, while the expression of a dominant negative mutant of GATA-3 or a GATA-3 shRNA construct reduced OPG mRNA and protein levels. GATA-3 deficient cells generated by expressing a GATA-3 shRNA construct were sensitive to apoptosis induced by etoposide and TNF-α. This apoptotic effect could be partly prevented by the co-treatment with exogenous OPG. Our results suggest new approaches to rescue diseases due to GATA-3 deficiency – such as in hypoparathyroidism, sensorineural deafness, and renal (HDR) syndrome – by OPG therapy.

Vitamin D deficiency in a patient with HDR syndrome

The case of a patient with clinical symptoms, laboratory and imaging findings of hypoparathyroidism, sensorineural deafness, renal dysplasia HDR, or Barakat syndrome (hypoparathyroidism, deafness, renal dysplasia), and vitamin D deficiency, is presented. A Caucasian man aged 51 years with a history of chronic hypocalcaemia since childhood, was admitted with hypertonia of the body and extremities, and loss of consciousness. On admission, he was found to have severe hypocalcaemia, hyperphosphataemia, severe hypoparathyroidism, low serum magnesium and mild renal insufficiency. Calcium gluconate was administered intravenously supplemented with magnesium, and the patient recovered consciousness while clinical and laboratory findings improved. Evaluation revealed left renal aplasia and sensorineural deafness affecting both ears. Vitamin D deficiency was also present. He was given calcium and vitamin D supplements orally, and the hypocalcaemia was corrected. This case is described as it is an extremely rare case of HDR syndrome with concurrent vitamin D deficiency.

The First Turkish Case of Hypoparathyroidism, Deafness and Renal Dysplasia (HDR) Syndrome

Hypoparathyroidism, deafness and renal dysplasia (HDR) syndrome is an autosomal dominant genetic disorder characterized by hypoparathyroidism, sensorineural deafness and renal dysplasia. We herein present the first Turkish patient with HDR syndrome, who has a p.R367X mutation. This report indicates that p.R367X is not a mutation specific for the Far Eastern populations and also that urological findings in infants with hypoparathyroidism should be carefully examined because clinical findings relating to the p.R367X mutation may show a variable age of onset.

Tumoral calcinosis in a patient with hypoparathyroidism, sensorineural deafness, and renal dysplasia syndrome undergoing hemodialysis

We describe a hemodialysis patient with hypoparathyroidism due to HDR (hypoparathyroidism, sensorineural deafness, and renal dysplasia) syndrome caused by GATA3 mutation. She presents tumoral calcinosis which is a rare complication of end-stage renal failure. A novel mutation of GATA3 is identified in this patient.

Hypoparathyroidism, sensorineural deafness, and renal dysgenesis syndrome with a GATA3 mutation

Hypoparathyroidism, sensorineural deafness, and renal dysgenesis syndrome is an autosomal dominant disease caused by mutations in the GATA3 gene on chromosome 10p15. We identified a patient diagnosed with hypoparathyroidism who also had a family history of hypoparathyroidism and sensorineural deafness, present in the father. The patient was subsequently diagnosed and found to be a heterozygote for an insertion mutation c.255_256ins4 (GTGC) in exon 2 of GATA3. His father was also confirmed to have the same mutation in GATA3.

Auditory and vestibular phenotypes associated with GATA3 mutation

OBJECTIVE

To report the auditory and vestibular phenotypes of patients with GATA3 mutation.

STUDY DESIGN

Case series of 6 patients.

SETTING

Tertiary referral center.

PATIENTS

All patients had the classic triad of GATA3 deficiency: hypoparathyroidism, hearing loss, and renal dysplasia. Patients (29-60 yr old; mean age, 42.5 yr; 3 male and 3 female subjects) were confirmed to have heterozygous mutations involving GATA3 by Sanger sequencing.

INTERVENTIONS

Behavioral audiometry, distortion product otoacoustic emissions (DPOAEs), and auditory brainstem responses (ABRs) were used to assess hearing. Rotational vestibular testing was used to assess vestibular function.

RESULTS

All patients with GATA3 mutation presented with hearing loss during childhood. The mean 3-frequency (0.5/1/2 kHz) pure tone average was 67 dB HL (range, 50-83 dB HL; SD, 9.3). The average speech discrimination score was 73% (range, 36%-100%; SD, 15.9). DPOAEs were absent in all patients. ABRs were remarkably robust and provided no evidence of retrocochlear dysfunction. Some patients complained of dizziness, but rotary chair testing was normal across participants for whom testing occurred.

CONCLUSION

Patients with GATA3 mutation present with early-onset sensorineural hearing loss (SNHL). DPOAEs were absent, supporting outer hair cell dysfunction, whereas ABRs were present and robust. Rotational vestibular testing revealed no evidence of abnormal horizontal semicircular canal function.

GATA3 mutation in a family with hypoparathyroidism, deafness and renal dysplasia syndrome

BACKGROUND

The hypoparathyroidism, deafness and renal dysplasia (HDR) syndrome is an autosomal dominant disorder primarily caused by GATA3 gene mutation. We report here a case that both of a Chinese boy and his father had HDR syndrome which caused by a novel mutation of GATA3.

METHODS

Polymerase chain reaction and DNA sequencing was performed to detect the exons of the GATA3 gene for mutation analysis.

RESULTS

Sequence analysis of GATA3 revealed a heterozygous nonsense mutation in this family: a mutation of GATA3 at exon 2 (c.515C >A) that resulted in a premature stop at codon 172 (p.S172X) with a loss of two zinc finger domains.

CONCLUSION

We identified a novel nonsense mutation which will expand the spectrum of HDR-associated GATA3 mutations.

Audiometric characteristics of a dutch family with a new mutation in GATA3 causing HDR syndrome

We present the case of a Dutch family with a new mutation (c523_528dup) in GATA3 causing HDR syndrome. HDR syndrome is characterised by hypoparathyroidism, deafness and renal defects. In this study, we describe the audiometric characteristics of 5 patients from this family. Their hearing impairment was congenital, bilateral and symmetric. Audiograms showed mild-to-moderate hearing impairment with a flat audiogram configuration. Higher frequencies tended to be affected more strongly. Cross-sectional analyses showed no progression, and a mean audiogram was established. Psychophysical measurements in 3 HDR patients - including speech reception in noise, loudness scaling, gap detection and difference limen for frequency - were obtained to assess hearing function in greater detail. Overall, the results of the psychophysical measurements indicated characteristics of outer hair cell loss. CT scanning showed no anomalies in 3 of the HDR patients. Although 2 patients displayed vestibular symptoms, no anomalies in the vestibular system were found by vestibulo-ocular examination. Our results are in agreement with the theory that outer hair cell malfunctioning can play a major role in HDR syndrome.

Seizure, deafness, and renal failure: a case of barakat syndrome

Barakat syndrome (also known as HDR syndrome) is an autosomal dominant disorder characterized by hypoparathyroidism, sensorineural deafness, and renal disease caused by mutation of the GATA3 gene located at chromosome 10p15. The exact prevalence of this disorder is not known but is very rare, with only about a dozen cases reported in the literature. Here, we report a case of 58-year-old man from Ardabil who presented with seizure due to hypocalcemia. Further history revealed bilateral deafness. Audiogram confirmed sensorineural hearing loss of both sides. His laboratory data were consistent with hypoparathyroidism and renal failure. He was diagnosed to have Barakat syndrome based on his clinical and laboratory data. In conclusion, we need to be aware of rare inherited conditions in a patient with abnormal physical and laboratory findings even though their initial presentation was seizure and hypocalcemia.