scholarly journals Molecular Basis, Diagnostic Challenges and Therapeutic Approaches of Alport Syndrome: A Primer for Clinicians

2021 ◽  
Vol 22 (20) ◽  
pp. 11063
Author(s):  
Raquel Martínez-Pulleiro ◽  
María García-Murias ◽  
Manuel Fidalgo-Díaz ◽  
Miguel Ángel García-González
Keyword(s):  
Kidney Disease ◽  
Alport Syndrome ◽  
Renal Involvement ◽  
Specific Treatment ◽  
Hereditary Disease ◽  
Pathophysiological Mechanism ◽  
Sequencing Technologies ◽  
Type Iv ◽  
Collagen Genes ◽  
Next Generation Sequencing Ngs

Alport syndrome is a genetic and hereditary disease, caused by mutations in the type IV collagen genes COL4A3, COL4A4 and COL4A5, that affects the glomerular basement membrane of the kidney. It is a rare disease with an underestimated prevalence. Genetic analysis of population cohorts has revealed that it is the second most common inherited kidney disease after polycystic kidney disease. Renal involvement is the main manifestation, although it may have associated extrarenal manifestations such as hearing loss or ocular problems. The degree of expression of the disease changes according to the gene affected and other factors, known or yet to be known. The pathophysiology is not yet fully understood, although some receptors, pathways or molecules are known to be linked to the disease. There is also no specific treatment for Alport syndrome; the most commonly used are renin–angiotensin–aldosterone system inhibitors. In recent years, diagnosis has come a long way, thanks to advances in DNA sequencing technologies such as next-generation sequencing (NGS). Further research at the genetic and molecular levels in the future will complete the partial vision of the pathophysiological mechanism that we have, and will allow us to better understand what is happening and how to solve it.

scholarly journals A novel variant in the COL4A3 gene: etiology of Alport syndrome type 2 in a 38-year-old male with suspected hereditary kidney disease

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Paula Sienes Bailo ◽  
José Luis Bancalero Flores ◽  
Raquel Lahoz Alonso ◽  
María Santamaría González ◽  
Alex Gutiérrez Dalmau ◽  
...  
Keyword(s):  
Kidney Disease ◽  
Alport Syndrome ◽  
Clinical Symptoms ◽  
Molecular Testing ◽  
Syndrome Type ◽  
Variant Of Uncertain Significance ◽  
Type Iv ◽  
Novel Variant ◽  
End Stage

ABSTRACT Objectives Patients with Alport syndrome develop progressive kidney function deterioration, sensorineural hearing loss, and ocular abnormalities. This condition is caused by mutations in COL4A5 (X-linked inheritance), COL4A3 and COL4A4 (autosomal dominant or recessive inheritance), and encoding type IV collagen α3, α4, and α5, respectively. If left untreated, clinical symptoms progress from microscopic hematuria to proteinuria, progressive kidney failure, and end-stage kidney disease. At present, kidney transplantation is the only effective approach. Next-generation sequencing is the method of choice for the diagnosis of this condition. Case presentation We report the case of a young man with chronic kidney disease who eventually underwent transplantation. Molecular testing made it possible to determine the etiology of his clinical symptoms and autosomal recessive Alport syndrome type 2. The patient was found to be a compound heterozygote for two missense variants (trans configuration) in the COL4A3 gene: A likely pathogenic variant c.4981C>T (p.Arg1661Cys) in exon 52 inherited from the mother (described elsewhere), and another variant of uncertain significance, c.943G>A (p.Gly315Ser), in exon 17 inherited from the father that has not been previously reported in the literature or found in relevant databases. Conclusions Following genetic confirmation, genetic counseling was provided to the patient and his direct relatives.

scholarly journals Identification of 17 mutations in ten exons in the COL4A5 collagen gene, but no mutations found in four exons in COL4A6: a study of 250 patients with hematuria and suspected of having Alport syndrome.

1996 ◽  
Vol 7 (5) ◽  
pp. 702-709 ◽  
Author(s):  
N Heiskari ◽  
X Zhang ◽  
J Zhou ◽  
A Leinonen ◽  
D Barker ◽  
...  
Keyword(s):  
Hot Spots ◽  
Alport Syndrome ◽  
Type Iv Collagen ◽  
Polymerase Chain Reaction Amplification ◽  
Col4a5 Gene ◽  
Type Iv ◽  
Reaction Amplification ◽  
Male Patients ◽  
Polymerase Chain ◽  
Collagen Genes

Conditions for polymerase chain-reaction amplification of ten exon regions (Exons 3, 7, 11 through 13, and 15 through 19) of the collagen COL4A5 gene and four exon regions (Exons 2, and 12 through 14) of the COL4A6 gene were sequenced and established in this study. These Type IV collagen genes contain 51 and 48 exons, respectively. The sequences of these exons were determined in the two genes in 250 male patients with hematuria and suspected Alport syndrome. Seventeen mutations were found in nine of the ten exons studied in the COL4A5 gene in 17 patients, whereas no mutations were identified in COL4A6. One mutation was identical in two patients known to be unrelated. The results indicate that mutations in COL4A5 that leading to renal failure are more frequent than those involved in classic Alport syndrome, and also that mutations in COL4A6 are not likely to cause this disease. Furthermore, mutations in COL4A5 are distributed quite randomly and no "hot spots" were found.

Alport Syndrome

2021 ◽  
pp. 373-375
Author(s):  
Karpagam J. ◽  
Pandimeena. P
Keyword(s):  
Hearing Loss ◽  
Alport Syndrome ◽  
Type Iv Collagen ◽  
Hereditary Disease ◽  
Collagen Gene ◽  
Dominant Form ◽  
Type Iv ◽  
Ocular Changes

Alport syndrome (AS) is a type IV collagen hereditary disease characterized by the association of progressive Hematuric nephritis, hearing loss, and, frequently, ocular changes. Mutations in the COL4A5 collagen gene are responsible for the more common X-linked dominant form of the disease.

Contribution of the Minor Chain Type IV Collagen Network to the Mechanics of the Ocular Lens Capsule

2012 ◽  
Author(s):  
Lazarina Gyoneva ◽  
Yoav Segal ◽  
Kevin D. Dorfman ◽  
Victor H. Barocas
Keyword(s):  
Alport Syndrome ◽  
Type Iv Collagen ◽  
Dry Weight ◽  
Hereditary Disease ◽  
Collagen Iv ◽  
Lens Capsule ◽  
Basement Membranes ◽  
Ocular Lens ◽  
Ocular Manifestations ◽  
Type Iv

The ocular lens capsule (LC) is a specialized basement membrane which completely surrounds the lens. The LC serves as an attachment point for lens epithelial and fiber cells, controls lens solute and water transport, and makes accommodation possible [1]. It is primarily composed of type IV collagen (65% of dry weight), laminin, nidogen, and proteoglycans, of which type IV collagen is the main-tension resisting element [1,2]. Collagen IV monomers organize into polygonal planar networks resembling chicken wire (Fig.1) [3]. There are six different collagen IV monomers, labeled α1(IV) to α6(IV) each produced by a separate gene – COL4A1 to COL4A6. Monomers form triple helical protomers in a highly selective manner. In nature, only three monomer combinations have been discovered: the [α1(IV)]2α2(IV) protomer, referred to as the major chain, is found in all basement membranes; the α3(IV)α4(IV)α5(IV) protomer (minor chain) is found only in few basement membranes including the LC; the [α5(IV)]2α6(IV) protomer is very rare and will not be discussed further. Protomers of the same type assemble with one another to form separate networks which are known to have some differences [4]. For example, the minor chain network is more cross-linked than the major chain network. In a hereditary disease called Alport syndrome, the minor chain network is completely missing in males due to a mutation in the COL4A5 gene (located on the X chromosome) which prevents production of the α5(IV) monomer. Male Alport syndrome patients have significant ocular manifestations such as anterior lenticonus (protrusion of the lens), cataract, and even lens rupture [5] and they exhibit significant thinning of the LC. Because 1) the minor network is more cross-linked than the major network, 2) its absence affects lens shape, and 3) the LC displays pathological disruptions when it is missing, we theorize that its presence confers additional mechanical strength to the LC. Therefore, the objective of this study is to assess the contribution of the minor chain network to the mechanics of the LC.

SGLT2 inhibitors – a potential treatment for Alport syndrome

2020 ◽  
Vol 134 (4) ◽  
pp. 379-388 ◽  
Author(s):  
Holly Mabillard ◽  
John A. Sayer
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Alport Syndrome ◽  
Sglt2 Inhibitors ◽  
Potential Candidate ◽  
Potential Treatment ◽  
Type Iv ◽  
Patients With Diabetes ◽  
Membrane Type ◽  
End Stage

Abstract Alport syndrome is a rare genetic disease that results in disordered basement membrane type IV collagen resulting in occular and auditory defects as well of progressive kidney disease. Although no ‘cure’ currently exists, therapeutic blockade of the renin–angiotensin–aldosterone system can slow the progression to end-stage kidney disease (ESKD). Clinical trials for treatments in preventing chronic kidney disease have largely been negative over the last two decades until recent trials have shown positive cardiovascular and renal outcomes of sodium–glucose co-transporter-2 (SGLT2) inhibitors in patients with diabetes mellitus. Although marketed as medications for Type 2 diabetes, SGLT2 inhibitors have been found to have additional properties that are nephroprotective which makes them a potential candidate for treatment for those with other forms of progressive kidney disease. This review discusses the evidence for the use of SGLT2 inhibitors as a potential treatment in Alport syndrome that may slow the progression of chronic kidney disease and prevent patients reaching ESKD.

Initial Next-Generation Sequencing (NGS) Results of Alport Syndrome

2019 ◽  
Author(s):  
Altuğ Koç ◽  
Elçin Bora ◽  
Tayfun Cinleti ◽  
Gizem Yıldız ◽  
Meral Torun Bayram ◽  
...  
Keyword(s):  
Next Generation Sequencing ◽  
Alport Syndrome ◽  
Next Generation ◽  
Next Generation Sequencing Ngs ◽  
Generation Sequencing

MO046NGS PANEL PERFORMANCE IN THE DIAGNOSIS OF HEREDITARY RENAL DISEASE IN SOUTHERN SPAIN

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
María del Mar Del Águila García ◽  
Antonio M Poyatos Andújar ◽  
Ana Isabel Morales García ◽  
Margarita Martínez Atienza ◽  
Susana García Linares ◽  
...  
Keyword(s):  
Kidney Disease ◽  
Renal Disease ◽  
Polycystic Kidney Disease ◽  
Genetic Study ◽  
Alport Syndrome ◽  
Autosomal Dominant ◽  
Kidney Diseases ◽  
Polycystic Kidney ◽  
Autosomal Dominant Polycystic Kidney ◽  
Hereditary Renal Disease

Abstract Background and Aims Hereditary renal disease (HRD) is still underdiagnosed: although we know aspects related to autosomal dominant polycystic kidney disease (ADPKD), we know little about the incidence and prevalence of other entities such as Alport syndrome. Altogether, HRD can represent 15% of individuals undergoing renal replacement therapy (RRT) or could even be higher. The advancement of genetics at the healthcare level let to achieve accurate and early renal diagnoses, as well as the incorporation of genetic counseling to families, all of which will result in better management of the disease in its initial stages and the possibility of offering reproductive options that avoid transmission to offspring. Our objective is to know the performance offered by the implementation of the ERH panel through Next Generation Sequencing (NGS) in our healthcare area. Method Observational-descriptive study of 259 probands (141 men / 118 women), mean age of 46 years (30 pediatric / 123 over 50 years), with chronic kidney disease and suspected hereditary cause attended in the specialized consultation of our centers from October 2018 to October 2020. The DNA extracted from leukocytes obtained by venipuncture was processed with Nephropathies Solution version 3 panel (SOPHiA Genetics) according to the manufacturer's protocol. This panel covers the coding regions and splicing junctions of 44 HRD-related genes such as nephrotic syndromes, polycystic kidney diseases, Bartter syndromes, Alport syndrome, CAKUT or tubulopathies (table 1). The sequencing of the libraries was done in a MiSeq (Illumina Inc), the bioinformatic analysis of the data and annotation of variants was performed using the SOPHiA DDM 5.8.0.3 software, and the revision of variants by consulting the main databases (ClinVar, Exac, HGMD, NCBI, PKD Foundation, LOVD). Results The panel was informative (pathogenic or probably pathogenic) in 80/259 patients (31%) and 56/259 cases (21.66%) of variants of uncertain significance (VSI) were detected. Autosomal dominant polycystic kidney disease accounted for 76.2% of the variants identified (56.2% PKD1, 20% PKD2), following Alport syndrome with 15% and the alterations in the PKHD1 gene associated with renal polycystic disease in its recessive form with about 4% (Figure 1). We have also identified a case of autosomal dominant tubulointerstitial kidney disease associated with the UMOD gene that was not suspected until the genetic study was performed. We highlight that 45% (36/80) of the variants identified as responsible for the renal disease are not yet described. Overall, the most prevalent type of mutation is that which produces displacement in the reading frame or frameshift (Figure 2). Individually, frameshift is the most frequent alteration in PKD1, PKD2 and COL4A5, while for PKHD1, COL4A3 and COL4A4 it is missense. Conclusion Our NGS HRD panel a) offers an adequate diagnostic performance at the healthcare level, with definitive results in 1 out of 3 cases and has also allowed the performance of many carrier studies among family members b) is able of diagnosing the most frequent disease, ADPKD and Alport syndrome, as well as unresolved or poorly characterized cases, and c) opens the horizon for new diagnoses, all without increasing costs by outsourcing services. All this makes the genetic study of renal pathology a useful and efficient strategy. These results encourage us to enhance the resources in this area that we consider to be of strategic value.

FC 012PRIMARY KIDNEY DISEASE IMPACTS OUTCOME IN CKD PREGNANCIES: COMPLICATIONS IN COL4A3-5 RELATED DISEASE (ALPORT SYNDROME) VS OTHER CKD PREGNANCIES

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
Rozemarijn Snoek ◽  
Margriet Gosselink ◽  
Liffert Vogt ◽  
Margriet De Jong ◽  
Agne Cerkauskaite ◽  
...  
Keyword(s):  
Kidney Disease ◽  
Pregnancy Outcomes ◽  
Alport Syndrome ◽  
Low Birthweight ◽  
Kidney Diseases ◽  
Related Disease ◽  
Ckd Stage ◽  
Before And After ◽  
Stage 1 ◽  
Italian Cohort

Abstract Background and Aims Chronic kidney disease (CKD) affects approximately 3% of pregnant women. CKD increases the risk of pregnancy complications such as prematurity, low birthweight and pre-eclampsia. Also, kidney function can deteriorate more quickly due to pregnancy. There is limited knowledge on pregnancy outcomes in specific kidney diseases. The aim of the ALPART network is to study pregnancy outcomes differentiated by CKD aetiology. We have started with COLA3-5 related disease (Alport syndrome), which is one of the most prevalent monogenic kidney diseases. Comparing outcomes in COLA3-5 related disease to pregnancies with other CKD aetiologies allows us to investigate whether this specific diagnosis impacts outcome in CKD pregnancies. Method The ALPART network is an international 15-center network, which aims to include ∼200 COLA3-5 related disease pregnancies. In this intermediary analysis, we present data on 109 pregnancies from 68 women with COLA3-5 related disease. We compared outcomes to a cohort of 457 CKD stage 1-2 patients (a similar CKD stage as our cohort) of diverse aetiology from a 2015 Italian study and 159,924 women from the general Dutch population. Results The main pregnancy and kidney outcomes are presented in Figure 1. Foetal outcomes were better in COLA3-5 pregnancies than in pregnancies of women with CKD stage 1-2 of diverse aetiology. We saw less prematurity (17% vs 36% respectively) and a higher mean birthweight of 3216 ± 663 gram compared to 2768 ± 680 in the Italian cohort. Maternal kidney outcomes should be interpreted with caution (>30% missing data): proteinuria (73%) and hypertension (30%) were more frequent in COLA3-5 pregnancies than the Italian cohort. In the ALPART cohort, 10% developed severe hypertension. Median eGFR was not impacted by pregnancy and decline of eGFR before and after pregnancy were not significantly different between groups. Conclusion Fetal outcomes in pregnancies with COLA3-5 related disease seem to be more favorable than in a cohort with mixed cause of CKD. In this intermediary analysis, proteinuria levels and frequency of new-onset hypertension in pregnancy are higher. There is no significant eGFR loss during pregnancy or increased eGFR deterioration in the long-term. The differences between COLA3-5 and general CKD pregnancies underscore the importance of investigating pregnancy outcomes in specific kidney disease phenotypes to ensure adequate (pre-) pregnancy counselling and care.

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