1
|
Khayat AM, Alshareef BG, Alharbi SF, AlZahrani MM, Alshangity BA, Tashkandi NF. Consanguineous Marriage and Its Association With Genetic Disorders in Saudi Arabia: A Review. Cureus 2024; 16:e53888. [PMID: 38465157 PMCID: PMC10924896 DOI: 10.7759/cureus.53888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2024] [Indexed: 03/12/2024] Open
Abstract
Consanguineous marriages, where spouses are related by blood, have been a longstanding practice in human history. The primary medical concern with consanguineous marriages is the increased risk of genetic disorders. When closely related individuals reproduce, there is a higher probability that both parents carry the same genetic mutation. In Arab countries, especially Saudi Arabia, the rate of consanguineous marriage is high compared with Western European and Asian countries. This high rate is directly proportionate with elevated risk of genetic disorders, including congenital heart diseases, renal diseases, and rare blood disorders. Additionally, it was noted that the rate of negative postnatal outcomes is higher in consanguineous marriages compared with the general population. These observations indicate the necessity of tackling this area and highlighting the consequences of this practice. In this review, we aim to discuss the current evidence regarding the association between consanguineous marriages and genetic disorders in Saudi Arabia.
Collapse
Affiliation(s)
| | | | - Sara F Alharbi
- Biotechnology, College of Science, Taif University, Taif, SAU
| | | | | | - Noha Farouk Tashkandi
- Medical Research, College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh, SAU
| |
Collapse
|
2
|
Ay E, Gurses E, Aslan F, Gulhan B, Alniacik A, Duzova A, Bajin MD, Sennaroglu L, Genc GA, Ozaltin F, Topaloglu R. Hearing Loss Related to Gene Mutations in Distal Renal Tubular Acidosis. Audiol Neurootol 2023; 28:350-359. [PMID: 37121229 DOI: 10.1159/000529486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2022] [Accepted: 01/30/2023] [Indexed: 05/02/2023] Open
Abstract
INTRODUCTION Distal renal tubular acidosis (dRTA) is a disease that may develop either primarily or secondarily, resulting from urinary acidification defects in distal tubules. Hearing loss may accompany primary forms of dRTA. This study aims to determine the characteristics of hearing loss due to different gene mutations in patients with dRTA. METHODS Behavioral and electrophysiological audiological evaluations were performed after otolaryngology examination in 21 patients with clinically diagnosed dRTA. Radiological imaging of the inner ear (n = 9) was conducted and results of genetic analyses using next-generation sequencing method (n = 16) were included. RESULTS Twenty-one patients with dRTA from 20 unrelated families, aged between 8 months and 33 years (median = 12, interquartile range = 20), participated. All patients with ATP6V1B1 mutations (n = 9) had different degrees of hearing loss. There was one patient with hearing loss in patients with ATP6V0A4 mutations (n = 6). One patient with the WDR72 mutation had normal hearing. Large vestibular aqueduct syndrome (LVAS) was detected in 6 (67%) of 9 patients whose radiological evaluation results were available. CONCLUSIONS LVAS is common in patients with dRTA and may influence the type and severity of hearing loss in these patients. The possibility of both congenital and late-onset and progressive hearing loss should be considered in dRTA patients. A regular audiological follow-up is essential for the early detection of a possible late-onset or progressive hearing loss in these patients.
Collapse
Affiliation(s)
- Ezgi Ay
- Department of Audiology, Baskent University Faculty of Health Sciences, Ankara, Turkey
| | - Emre Gurses
- Department of Audiology, Hacettepe University Faculty of Health Sciences, Ankara, Turkey
| | - Filiz Aslan
- Department of Audiology, Hacettepe University Faculty of Health Sciences, Ankara, Turkey
| | - Bora Gulhan
- Department of Pediatric Nephrology, Hacettepe University Faculty of Medicine, Ankara, Turkey
| | - Asuman Alniacik
- Department of Audiology, Baskent University Faculty of Health Sciences, Ankara, Turkey
| | - Ali Duzova
- Department of Pediatric Nephrology, Hacettepe University Faculty of Medicine, Ankara, Turkey
| | - Munir Demir Bajin
- Department of Ear Nose and Throat, Hacettepe University Faculty of Medicine, Ankara, Turkey
| | - Levent Sennaroglu
- Department of Ear Nose and Throat, Hacettepe University Faculty of Medicine, Ankara, Turkey
| | - Gulsum Aydan Genc
- Department of Audiology, Hacettepe University Faculty of Health Sciences, Ankara, Turkey
| | - Fatih Ozaltin
- Department of Pediatric Nephrology, Hacettepe University Faculty of Medicine, Ankara, Turkey
- Nephrogenetics Laboratory, Hacettepe University Faculty of Medicine, Ankara, Turkey
| | - Rezan Topaloglu
- Department of Pediatric Nephrology, Hacettepe University Faculty of Medicine, Ankara, Turkey
| |
Collapse
|
3
|
Abstract
Distal renal tubular acidosis (DRTA) is defined as hyperchloremic, non-anion gap metabolic acidosis with impaired urinary acid excretion in the presence of a normal or moderately reduced glomerular filtration rate. Failure in urinary acid excretion results from reduced H+ secretion by intercalated cells in the distal nephron. This results in decreased excretion of NH4+ and other acids collectively referred as titratable acids while urine pH is typically above 5.5 in the face of systemic acidosis. The clinical phenotype in patients with DRTA is characterized by stunted growth with bone abnormalities in children as well as nephrocalcinosis and nephrolithiasis that develop as the consequence of hypercalciuria, hypocitraturia, and relatively alkaline urine. Hypokalemia is a striking finding that accounts for muscle weakness and requires continued treatment together with alkali-based therapies. This review will focus on the mechanisms responsible for impaired acid excretion and urinary potassium wastage, the clinical features, and diagnostic approaches of hypokalemic DRTA, both inherited and acquired.
Collapse
|
4
|
di Palmo E, Gallucci M, Tronconi E, Bergamaschi R, Cazzato S, La Scola C, Ricci G, Pession A. Carbonic Anhydrase II Deficiency: A Rare Case of Severe Obstructive Sleep Apnea. Front Pediatr 2018; 6:213. [PMID: 30109220 PMCID: PMC6079206 DOI: 10.3389/fped.2018.00213] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 07/11/2018] [Indexed: 11/16/2022] Open
Abstract
The term osteopetrosis describes a group of rare hereditary diseases of the skeleton, characterized by an increase in bone density, caused by a defect in the development or function of osteoclasts. It comprises a clinically and genetically heterogeneous conditions ranging from infantile onset life-threatening forms to mildest adult onset forms. "Malignant" osteopetrosis is characterized by bone fragility, short stature, compressive neuropathies, hypocalcaemia, pancytopaenia. The deficiency of carbonic anhydrase II causes a moderate form, presenting classically as a triad of osteopetrosis, renal tubular acidosis (RTA), and cerebral calcification. This condition leads to specific craniofacial dysmorphisms associated with upper airway obstruction that may result in obstructive sleep apnea. Herein we report a case of osteopetrosis with RTA associated with severe OSAS successfully treated with continuous positive airway pressure (CPAP).
Collapse
Affiliation(s)
- Emanuela di Palmo
- Department of Pediatrics, S. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
| | - Marcella Gallucci
- Department of Pediatrics, S. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
| | - Elena Tronconi
- Department of Pediatrics, S. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
| | - Rosalba Bergamaschi
- Pediatric Emergency Unit, S. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
| | - Salvatore Cazzato
- Department of Mother and Child Health, Salesi Children's Hospital, Ancona, Italy
| | - Claudio La Scola
- Department of Pediatrics, S. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
| | - Giampaolo Ricci
- Department of Pediatrics, S. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
| | - Andrea Pession
- Department of Pediatrics, S. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
| |
Collapse
|
5
|
Alsharidi A, Al-Hamed M, Alsuwaida A. Carbonic anhydrase II deficiency: report of a novel mutation. CEN Case Rep 2015; 5:108-112. [PMID: 28509178 DOI: 10.1007/s13730-015-0205-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 11/05/2015] [Indexed: 10/22/2022] Open
Abstract
Carbonic anhydrase II (CAII) deficiency is an autosomal recessive disorder characterized by renal tubular acidosis, osteopetrosis, recurrent bone fractures, renal stones, growth failure, and mental retardation. Several cases have been reported in Saudi Arabia with homozygous mutations in CA2 consistent with a high degree of consanguinity. We report a case of carbonic anhydrase II deficiency with short stature, mixed renal tubular acidosis, recurrent bone fractures due to trivial trauma, recurrent renal stones and cerebral calcification. This patient was compound heterozygous for a novel CA2 mutation and a previously reported mutation in Arabs.
Collapse
Affiliation(s)
- Aynaa Alsharidi
- Department of Medicine (38), College of Medicine, King Saud University, P.O. Box 2925, Riyadh, 11461, Kingdom of Saudi Arabia
| | - Mohammad Al-Hamed
- Department of Genetics, King Faisal Specialist and Research Center, Riyadh, Kingdom of Saudi Arabia
| | - Abdulkareem Alsuwaida
- Department of Medicine (38), College of Medicine, King Saud University, P.O. Box 2925, Riyadh, 11461, Kingdom of Saudi Arabia.
| |
Collapse
|
6
|
Kari JA, Bockenhauer D, Stanescu H, Gari M, Kleta R, Singh AK. Consanguinity in Saudi Arabia: a unique opportunity for pediatric kidney research. Am J Kidney Dis 2013; 63:304-10. [PMID: 24239020 DOI: 10.1053/j.ajkd.2013.08.033] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 08/02/2013] [Indexed: 02/07/2023]
Abstract
Identification of disease-related genes is a critical step in understanding the molecular basis of disease and developing targeted therapies. The genetic study of diseases occurring in the offspring of consanguineous unions is a powerful way to discover new disease genes. Pediatric nephrology provides an excellent example because ∼70% of cases of kidney disease in childhood are congenital with a likely genetic basis. This percentage is likely to be even higher in countries with a high consanguinity rate, such as the Kingdom of Saudi Arabia. However, there are a number of challenges, such as cultural, legal, and religious restrictions, that should be appreciated before carrying out genetic research in a tradition-bound country. In this article, we discuss the background, opportunities, and challenges involved with this unique opportunity to conduct studies of such genetic disorders. Keys to success include collaboration and an understanding of local traditions and laws.
Collapse
Affiliation(s)
- Jameela A Kari
- Department of Pediatrics, Faculty of Medicine, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia.
| | - Detlef Bockenhauer
- Institute of Child Health, University College London, London, United Kingdom
| | - Horia Stanescu
- Institute of Child Health, University College London, London, United Kingdom
| | - Mamdooh Gari
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Robert Kleta
- Institute of Child Health, University College London, London, United Kingdom
| | - Ajay K Singh
- Renal Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| |
Collapse
|
7
|
Batlle D, Haque SK. Genetic causes and mechanisms of distal renal tubular acidosis. Nephrol Dial Transplant 2013; 27:3691-704. [PMID: 23114896 DOI: 10.1093/ndt/gfs442] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The primary or hereditary forms of distal renal tubular acidosis (dRTA) have received increased attention because of advances in the understanding of the molecular mechanism, whereby mutations in the main proteins involved in acid-base transport result in impaired acid excretion. Dysfunction of intercalated cells in the collecting tubules accounts for all the known genetic causes of dRTA. These cells secrete protons into the tubular lumen through H(+)-ATPases functionally coupled to the basolateral anion exchanger 1 (AE1). The substrate for both transporters is provided by the catalytic activity of the cytosolic carbonic anhydrase II (CA II), an enzyme which is also present in the proximal tubular cells and osteoclasts. Mutations in ATP6V1B1, encoding the B-subtype unit of the apical H(+) ATPase, and ATP6V0A4, encoding the a-subtype unit, lead to the loss of function of the apical H(+) ATPase and are usually responsible for patients with autosomal recessive dRTA often associated with early or late sensorineural deafness. Mutations in the gene encoding the cytosolic CA II are associated with the autosomal recessive syndrome of osteopetrosis, mixed distal and proximal RTA and cerebral calcification. Mutations in the AE1, the gene that encodes the Cl(-)/HCO(3)(-) exchanger, usually present as dominant dRTA, but a recessive pattern has been recently described. Several studies have shown trafficking defects in the mutant protein rather than the lack of function as the major mechanism underlying the pathogenesis of dRTA from AE1 mutations.
Collapse
|
8
|
Kari JA. Pediatric renal diseases in the Kingdom of Saudi Arabia. World J Pediatr 2012; 8:217-21. [PMID: 22886193 DOI: 10.1007/s12519-012-0360-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 04/03/2012] [Indexed: 12/20/2022]
Abstract
BACKGROUND Pediatric nephrology is a growing subspecialty in the Kingdom of Saudi Arabia (KSA). Pediatric nephrologists are challenged with a different spectrum of renal diseases. Moreover, there is a lack of epidemiological studies for most of these diseases. In this article, we discuss the spectrum of renal diseases in KSA and highlight the differences that exist between reports from KSA and those from other countries. DATA SOURCES PubMed and MEDLINE databases were searched for articles on pediatric renal diseases. RESULTS Genetically mediated renal diseases are considerably high in KSA. Congenital and infantile nephrotic syndrome is higher in KSA than in other countries. Post-infectious glomerular pathology is rather common but is declining, while tropical infections such as schistosomiasis have been controlled. Neurogenic bladder caused by spinal lesion is an important cause of chronic kidney disease among pediatric patients. Renal stones are also more frequent in KSA than in other countries. CONCLUSIONS The spectrum of pediatric renal diseases in KSA is rather different from that reported from Western countries. More epidemiological studies are required to understand the actual incidence and nature of these diseases.
Collapse
Affiliation(s)
- Jameela Abdulaziz Kari
- Department of Pediatrics, Faculty of Medicine, Department of King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia.
| |
Collapse
|
9
|
Bosley TM, Salih MA, Alorainy IA, Islam MZ, Oystreck DT, Suliman OSM, al Malki S, Suhaibani AH, Khiari H, Beckers S, van Wesenbeeck L, Perdu B, AlDrees A, Elmalik SA, Van Hul W, Abu-Amero KK. The neurology of carbonic anhydrase type II deficiency syndrome. Brain 2011; 134:3502-15. [PMID: 22120147 DOI: 10.1093/brain/awr302] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Carbonic anhydrase type II deficiency syndrome is an uncommon autosomal recessive disease with cardinal features including osteopetrosis, renal tubular acidosis and brain calcifications. We describe the neurological, neuro-ophthalmological and neuroradiological features of 23 individuals (10 males, 13 females; ages at final examination 2-29 years) from 10 unrelated consanguineous families with carbonic anhydrase type II deficiency syndrome due to homozygous intron 2 splice site mutation (the 'Arabic mutation'). All patients had osteopetrosis, renal tubular acidosis, developmental delay, short stature and craniofacial disproportion with large cranial vault and broad forehead. Mental retardation was present in approximately two-thirds and varied from mild to severe. General neurological examinations were unremarkable except for one patient with brisk deep tendon reflexes and two with severe mental retardation and spastic quadriparesis. Globes and retinae were normal, but optic nerve involvement was present in 23/46 eyes and was variable in severity, random in occurrence and statistically correlated with degree of optic canal narrowing. Ocular motility was full except for partial ductional limitations in two individuals. Saccadic abnormalities were present in two, while half of these patients had sensory or accommodative strabismus, and seven had congenital nystagmus. These abnormalities were most commonly associated with afferent disturbances, but a minor brainstem component to this disorder remains possible. All internal auditory canals were normal in size, and no patient had clinically significant hearing loss. Neuroimaging was performed in 18 patients and repeated over as long as 10 years. Brain calcification was generally progressive and followed a distinct distribution, involving predominantly basal ganglia and thalami and grey-white matter junction in frontal regions more than posterior regions. At least one child had no brain calcification at age 9 years, indicating that brain calcification may not always be present in carbonic anhydrase type II deficiency syndrome during childhood. Variability of brain calcification, cognitive disturbance and optic nerve involvement may imply additional genetic or epigenetic influences affecting the course of the disease. However, the overall phenotype of the disorder in this group of patients was somewhat less severe than reported previously, raising the possibility that early treatment of systemic acidosis with bicarbonate may be crucial in the outcome of this uncommon autosomal recessive problem.
Collapse
Affiliation(s)
- Thomas M Bosley
- Department of Ophthalmology and Paediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Swayamprakasam AP, Stover E, Norgett E, Blake-Palmer KG, Cunningham MJ, Karet FE. Importance of early audiologic assessment in distal renal tubular acidosis. Int Med Case Rep J 2011; 4:7-11. [PMID: 23754897 PMCID: PMC3658229 DOI: 10.2147/imcrj.s13667] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Autosomal recessive distal renal tubular acidosis is usually a severe disease of childhood, often presenting as failure to thrive in infancy. It is often, but not always, accompanied by sensorineural hearing loss, the clinical severity and age of onset of which may be different from the other clinical features. Mutations in either ATP6V1B1 or ATP6V0A4 are the chief causes of primary distal renal tubular acidosis with or without hearing loss, although the loss is often milder in the latter. We describe a kindred with compound heterozygous alterations in ATP6V0A4, where hearing loss was formally diagnosed late in both siblings such that they missed early opportunities for hearing support. This kindred highlights the importance of routine audiologic assessments of all children with distal renal tubular acidosis, irrespective either of age at diagnosis or of which gene is mutated. In addition, when diagnostic genetic testing is undertaken, both genes should be screened irrespective of current hearing status. A strategy for this is outlined.
Collapse
|
11
|
Yashima T, Noguchi Y, Kawashima Y, Rai T, Ito T, Kitamura K. Novel ATP6V1B1 mutations in distal renal tubular acidosis and hearing loss. Acta Otolaryngol 2010; 130:1002-8. [PMID: 20233014 DOI: 10.3109/00016481003631529] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONCLUSION Novel ATP6V1B1 mutations were found in a patient with distal renal tubular acidosis (dRTA), hearing loss (HL), and enlargement of the vestibular aqueduct (EVA). The deterioration of HL and vertiginous attacks may be associated with the disruption of the endolymph pH homeostasis. OBJECTIVES To study the audiovestibular functions and to identify the causative gene. METHODS This study enrolled a Japanese family, where the proband showed type 1 dRTA, early onset HL, and bilateral EVA. A deterioration of HL occurred several times in both ears. Vertiginous attacks were always associated with a deterioration of HL. Audiovestibular examinations included distortion product otoacoustic emissions (DPOAEs), auditory brainstem responses (ABRs), caloric testing, and vestibular evoked myogenic potentials (VEMPs). Direct sequencing was utilized to screen for ATP6V1B1, SLC26A4, and GJB2 mutations. RESULTS The findings of DPOAEs and ABRs indicated cochlear HL. The vestibular function was thought to be mildly impaired according to the caloric responses and VEMP findings. Two novel ATP6V1B1 mutations of a heterozygous 15 base-pair deletion (c.756_770del) in exon 7 and a heterozygous 1 base-pair insertion (c.1242_1243insC) in exon 12 were detected in a compound heterozygous state. No mutation was identified in either SLC26A4 or GJB2.
Collapse
Affiliation(s)
- Takatoshi Yashima
- Department of Otolaryngology, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo113-8519, Japan
| | | | | | | | | | | |
Collapse
|
12
|
Öğütcen-Toller M, Tek M, Şener İ, Bereket C, İnal S, Özden B. Intractable Bimaxillary Osteomyelitis in Osteopetrosis: Review of the Literature and Current Therapy. J Oral Maxillofac Surg 2010; 68:167-75. [DOI: 10.1016/j.joms.2005.07.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Accepted: 07/14/2005] [Indexed: 10/20/2022]
|
13
|
Abstract
Inherited acidosis may result from a primary renal defect in acid-base handling, emphasizing the central role of the kidney in control of body pH; as a secondary phenomenon resulting from abnormal renal electrolyte handling; or from excess production of acid elsewhere in the body. Here, we review our current understanding of the inherited renal acidoses at a genetic and molecular level.
Collapse
Affiliation(s)
- Andrew C Fry
- Department of Medical Genetics and Division of Renal Medicine, University of Cambridge, Cambridge Institute for Medical Research, UK
| | | |
Collapse
|
14
|
Gil H, Santos F, García E, Alvarez MV, Ordóñez FA, Málaga S, Coto E. Distal RTA with nerve deafness: clinical spectrum and mutational analysis in five children. Pediatr Nephrol 2007; 22:825-8. [PMID: 17216496 DOI: 10.1007/s00467-006-0417-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Revised: 11/22/2006] [Accepted: 12/08/2006] [Indexed: 10/23/2022]
Abstract
Distal renal tubular acidosis (RTA) with nerve deafness is caused by mutations in the ATP6V1B1 gene causing defective function of the H+ -ATPase proton pump. We report five acidotic children (four males) from four unrelated families: blood pH 7.21-7.33, serum bicarbonate 10.8-14.7 mEq/l, minimum urinary pH 6.5-7.1 and fractional excretion of bicarbonate in the presence of normal bicarbonatemia 1.1-5.7%. Growth retardation and nephrocalcinosis, but not hypercalciuria, were common presenting manifestations. Hearing was normally preserved in one of the patients whose sister was severely deaf. One child was homozygous for a known mutation in exon 1: C>T (R31X). Three children were homozygous for a splicing mutation, intron 6 + 1G>A. The other patient was a compound heterozygote, having this mutation and a previously unreported mutation in exon 10: G>A (E330K). Our report shows that hearing loss is not always present in the syndrome of distal renal tubular acidosis with nerve deafness and the absence of hypercalciuria at diagnosis and describes a new mutation responsible for the disease in the ATP6V1B1 gene.
Collapse
Affiliation(s)
- Helena Gil
- Hospital Universitario Central de Asturias, Asturias, Spain
| | | | | | | | | | | | | |
Collapse
|
15
|
Abstract
Not all vacuolar-type H(+)-ATPases (V-ATPases) are alike; those responsible for H(+) movement across plasma membranes contain some different, tissue-specific subunit isoforms. This brief review outlines those that have special relevance to the kidney, and illustrates their importance by describing various human diseases where loss of local proton pump function not only confers a severe phenotype, but has revealed related tissues where these same isoforms are expressed, signifying their physiological importance.
Collapse
Affiliation(s)
- Fiona E Karet
- Division of Renal Medicine and Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Box 139, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 2XY, UK.
| |
Collapse
|
16
|
Shinjo Y, Kaga K, Igarashi T. Distal renal tubular acidosis associated with large vestibular aqueduct and sensorineural hearing loss. Acta Otolaryngol 2005; 125:667-70. [PMID: 16076719 DOI: 10.1080/00016480510028483] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
CONCLUSIONS Hearing loss and equilibrium dysfunction have different etiologies in patients with large vestibular aqueduct syndrome. We suggest that all children with distal renal tubular acidosis (dRTA) should be subjected to an equilibrium study and audiological evaluation, as well as to a CT or MRI scan. OBJECTIVE dRTA has been described in association with sensorineural hearing loss, but there are no reported cases that have been examined in detail using audiological and equilibrium studies. We report here a case of progressive sensorineural hearing loss with a large vestibular aqueduct and dRTA, and the results of audiological and equilibrium studies. MATERIAL AND METHODS A 31-year-old female presented with hearing loss, tinnitus and vertigo. She had been treated with oral sodium citrate, potassium citrate and potassium chloride supplementation because of dRTA since the age of 1 month. RESULTS The pure-tone audiogram of the patient was off the scale for the right ear and showed progressive sensorineural hearing loss for the left ear. Ice-water caloric testing showed canal paresis on the left side. Temporal bone CT and inner ear MRI revealed a large vestibular aqueduct and a large endolymphatic sac on both sides.
Collapse
Affiliation(s)
- Yukiko Shinjo
- Department of Otolaryngology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
| | | | | |
Collapse
|
17
|
Hahn H, Kang HG, Ha IS, Cheong HI, Choi Y. ATP6B1 gene mutations associated with distal renal tubular acidosis and deafness in a child. Am J Kidney Dis 2003; 41:238-43. [PMID: 12500243 DOI: 10.1053/ajkd.2003.50014] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A large proportion of autosomal recessive distal renal tubular acidosis (RTA) is associated with mutations in the ATP6B1 gene encoding the B1 subunit of H+-ATPase. H+-ATPase is one of the key membrane transporters for net acid excretion in the alpha-intercalated cells of the medullary collecting duct. Sensorineural hearing loss frequently accompanies this type of distal RTA. Mutational analysis of the ATP6B1 gene in a 9-year-old Korean boy with distal RTA and sensorineural hearing loss found 2 heterozygous missense point mutations. Although a single case report, this is the second report documenting ATP6B1 mutations in recessive distal RTA with sensorineural hearing loss after the original report by Karet et al and confirms the novelty of these mutations.
Collapse
Affiliation(s)
- Hyewon Hahn
- Department of Pediatrics, Seoul National University Children's Hospital and Clinical Research Institute, Ulsan Medical University, Asan Medical Center, Seoul, Korea
| | | | | | | | | |
Collapse
|
18
|
Stover EH, Borthwick KJ, Bavalia C, Eady N, Fritz DM, Rungroj N, Giersch ABS, Morton CC, Axon PR, Akil I, Al-Sabban EA, Baguley DM, Bianca S, Bakkaloglu A, Bircan Z, Chauveau D, Clermont MJ, Guala A, Hulton SA, Kroes H, Li Volti G, Mir S, Mocan H, Nayir A, Ozen S, Rodriguez Soriano J, Sanjad SA, Tasic V, Taylor CM, Topaloglu R, Smith AN, Karet FE. Novel ATP6V1B1 and ATP6V0A4 mutations in autosomal recessive distal renal tubular acidosis with new evidence for hearing loss. J Med Genet 2002; 39:796-803. [PMID: 12414817 PMCID: PMC1735017 DOI: 10.1136/jmg.39.11.796] [Citation(s) in RCA: 201] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Autosomal recessive distal renal tubular acidosis (rdRTA) is characterised by severe hyperchloraemic metabolic acidosis in childhood, hypokalaemia, decreased urinary calcium solubility, and impaired bone physiology and growth. Two types of rdRTA have been differentiated by the presence or absence of sensorineural hearing loss, but appear otherwise clinically similar. Recently, we identified mutations in genes encoding two different subunits of the renal alpha-intercalated cell's apical H(+)-ATPase that cause rdRTA. Defects in the B1 subunit gene ATP6V1B1, and the a4 subunit gene ATP6V0A4, cause rdRTA with deafness and with preserved hearing, respectively. We have investigated 26 new rdRTA kindreds, of which 23 are consanguineous. Linkage analysis of seven novel SNPs and five polymorphic markers in, and tightly linked to, ATP6V1B1 and ATP6V0A4 suggested that four families do not link to either locus, providing strong evidence for additional genetic heterogeneity. In ATP6V1B1, one novel and five previously reported mutations were found in 10 kindreds. In 12 ATP6V0A4 kindreds, seven of 10 mutations were novel. A further nine novel ATP6V0A4 mutations were found in "sporadic" cases. The previously reported association between ATP6V1B1 defects and severe hearing loss in childhood was maintained. However, several patients with ATP6V0A4 mutations have developed hearing loss, usually in young adulthood. We show here that ATP6V0A4 is expressed within the human inner ear. These findings provide further evidence for genetic heterogeneity in rdRTA, extend the spectrum of disease causing mutations in ATP6V1B1 and ATP6V0A4, and show ATP6V0A4 expression within the cochlea for the first time.
Collapse
Affiliation(s)
- E H Stover
- Department of Medical Genetics, University of Cambridge, UK
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Affiliation(s)
- Fiona E Karet
- Wellcome Trust Senior Research Fellow and Honorary Consultant in Renal Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom.
| |
Collapse
|
20
|
Abstract
The primary or hereditary form of distal renal tubular acidosis (dRTA), although rare, has received increased attention recently because of dramatic advances in the understanding of its genetic basis. The final regulation of renal acid excretion is effected by various acid/base transporters localized in specialized cells in the cortical collecting and outer medullary collecting tubules. Inherited defects in two of the key acid/base transporters involved in distal acidification, as well as mutations in the cytosolic carbonic anhydrase gene, can cause dRTA. The syndrome is inherited in both autosomal dominant and recessive patterns; patients with recessive dRTA present with either acute illness or growth failure at a young age, sometimes accompanied by deafness, whereas dominant dRTA is usually a milder disease and involves no hearing loss. The AE1 gene encodes two Cl-/HCO3- exchangers that are expressed in the erythrocyte and in the acid-secreting intercalated cells of the kidney. AE1 contributes to urinary acidification by providing the major exit route for HCO3- across the basolateral membrane. Several mutations in the AE1 gene cosegregate with dominant dRTA. The modest degree of hypofunction exhibited in vitro by these mutations, however, does not explain the abnormal distal acidification phenotype. Other AE1 mutations have been linked to a recessive syndrome of dRTA and hemolytic anemia in which hypofunction can be discerned by in vitro studies. Several mutations in the carbonic anyhdrase II gene are associated with the autosomal recessive syndrome of osteopetrosis, renal tubular acidosis, and cerebral calcification. Some of these individuals present with deafness of the conductive type. By contrast, more recent studies have shown that mutations in ATP6B1, encoding the B-subtype unit of the apical H(+) ATPase, are responsible for a group of patients with autosomal recessive dRTA associated with sensorineural deafness. Thus, the presence of deafness and the type provide an important clue to the genetic lesion underlying hereditary dRTA.
Collapse
Affiliation(s)
- D Batlle
- Division of Nephrology/Hypertension, Northwestern University Medical School, 303 E. Chicago Avenue, Chicago, Illinois 60611-3008, USA.
| | | | | | | |
Collapse
|
21
|
Karet FE, Finberg KE, Nayir A, Bakkaloglu A, Ozen S, Hulton SA, Sanjad SA, Al-Sabban EA, Medina JF, Lifton RP. Localization of a gene for autosomal recessive distal renal tubular acidosis with normal hearing (rdRTA2) to 7q33-34. Am J Hum Genet 1999; 65:1656-65. [PMID: 10577919 PMCID: PMC1288376 DOI: 10.1086/302679] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/1999] [Accepted: 09/08/1999] [Indexed: 02/04/2023] Open
Abstract
Failure of distal nephrons to excrete excess acid results in the "distal renal tubular acidoses" (dRTA). Early childhood features of autosomal recessive dRTA include severe metabolic acidosis with inappropriately alkaline urine, poor growth, rickets, and renal calcification. Progressive bilateral sensorineural hearing loss (SNHL) is evident in approximately one-third of patients. We have recently identified mutations in ATP6B1, encoding the B-subunit of the collecting-duct apical proton pump, as a cause of recessive dRTA with SNHL. We now report the results of genetic analysis of 13 kindreds with recessive dRTA and normal hearing. Analysis of linkage and molecular examination of ATP6B1 indicated that mutation in ATP6B1 rarely, if ever, accounts for this phenotype, prompting a genomewide linkage search for loci underlying this trait. The results strongly supported linkage with locus heterogeneity to a segment of 7q33-34, yielding a maximum multipoint LOD score of 8.84 with 68% of kindreds linked. The LOD-3 support interval defines a 14-cM region flanked by D7S500 and D7S688. That 4 of these 13 kindreds do not support linkage to rdRTA2 and ATP6B1 implies the existence of at least one additional dRTA locus. These findings establish that genes causing recessive dRTA with normal and impaired hearing are different, and they identify, at 7q33-34, a new locus, rdRTA2, for recessive dRTA with normal hearing.
Collapse
MESH Headings
- Acidosis, Renal Tubular/genetics
- Acidosis, Renal Tubular/physiopathology
- Adenosine Triphosphatases/genetics
- Adult
- Anion Transport Proteins
- Antiporters
- Child
- Child, Preschool
- Chromosome Mapping
- Chromosomes, Human, Pair 2/genetics
- Chromosomes, Human, Pair 7/genetics
- Consanguinity
- DNA Mutational Analysis
- Female
- Genes, Recessive/genetics
- Hearing/genetics
- Hearing/physiology
- Humans
- Hydrogen-Ion Concentration
- Infant
- Infant, Newborn
- Lod Score
- Male
- Membrane Proteins/genetics
- Middle East
- Molecular Sequence Data
- Pakistan
- Pedigree
- Polymorphism, Single-Stranded Conformational
- SLC4A Proteins
Collapse
Affiliation(s)
- F E Karet
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 2XY, United Kingdom.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Karet FE, Finberg KE, Nelson RD, Nayir A, Mocan H, Sanjad SA, Rodriguez-Soriano J, Santos F, Cremers CW, Di Pietro A, Hoffbrand BI, Winiarski J, Bakkaloglu A, Ozen S, Dusunsel R, Goodyer P, Hulton SA, Wu DK, Skvorak AB, Morton CC, Cunningham MJ, Jha V, Lifton RP. Mutations in the gene encoding B1 subunit of H+-ATPase cause renal tubular acidosis with sensorineural deafness. Nat Genet 1999; 21:84-90. [PMID: 9916796 DOI: 10.1038/5022] [Citation(s) in RCA: 470] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
H+-ATPases are ubiquitous in nature; V-ATPases pump protons against an electrochemical gradient, whereas F-ATPases reverse the process, synthesizing ATP. We demonstrate here that mutations in ATP6B1, encoding the B-subunit of the apical proton pump mediating distal nephron acid secretion, cause distal renal tubular acidosis, a condition characterized by impaired renal acid secretion resulting in metabolic acidosis. Patients with ATP6B1 mutations also have sensorineural hearing loss; consistent with this finding, we demonstrate expression of ATP6B1 in cochlea and endolymphatic sac. Our data, together with the known requirement for active proton secretion to maintain proper endolymph pH, implicate ATP6B1 in endolymph pH homeostasis and in normal auditory function. ATP6B1 is the first member of the H+-ATPase gene family in which mutations are shown to cause human disease.
Collapse
MESH Headings
- Acidosis, Renal Tubular/complications
- Acidosis, Renal Tubular/enzymology
- Acidosis, Renal Tubular/genetics
- Base Sequence
- Child, Preschool
- Chromosomes, Human, Pair 2
- Cochlea/metabolism
- Female
- Genes, Recessive
- Genetic Linkage
- Hearing Loss, Sensorineural/complications
- Hearing Loss, Sensorineural/enzymology
- Hearing Loss, Sensorineural/genetics
- Humans
- Infant
- Male
- Molecular Sequence Data
- Mutation
- Pedigree
- Proton-Translocating ATPases/genetics
- Proton-Translocating ATPases/metabolism
Collapse
Affiliation(s)
- F E Karet
- Howard Hughes Medical Institute, Department of Medicine, Yale University School of Medicine, Boyer Center for Molecular Medicine, New Haven, Connecticut 06510, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|