Alport syndrome and leiomyomatosis: the first deletion extending beyond COL4A6 intron 2

Systematic Review of Management Strategies for Alport Syndrome: Implications for Male Patients

Background and Aims

Alport Syndrome (AS) is a rare genetic disorder characterized by progressive kidney disease, hearing loss, and ocular abnormalities, with an incidence of approximately 1 in 50,000 newborns. Due to the severity of the disease, particularly in males with X-linked inheritance, this systematic review consolidates current management strategies, highlighting advancements and existing gaps in treatment options.

Methods

This systematic review followed a protocol registered on the OSF platform (osf. io/k86ms). A comprehensive search of PubMed, Web of Science, Scopus, Cochrane Library, Embase, ClinicalTrials.gov, and the WHO ICTRP was completed by December 24, 2023. Studies eligible for inclusion were clinical trials or observational studies evaluating AS management. Four clinical trials from six publications and two observational studies met the inclusion criteria. The risk of bias was assessed using the Cochrane ROB 2 tool for clinical trials and the Newcastle-Ottawa Scale (NOS) for observational studies. Key interventions examined included bardoxolone methyl, ramipril, and losartan.

Results

Bardoxolone methyl, ramipril, and losartan demonstrated potential benefits in slowing renal disease progression in AS. Observational studies indicated that early intervention might delay the need for dialysis and improve life expectancy. However, significant heterogeneity among studies precluded quantitative synthesis. Ongoing studies on AS management encompass 25 trials involving 52,135 participants, reflecting an active area of research.

Conclusion

Bardoxolone methyl, ramipril, and losartan show promise in delaying renal failure in AS. Nonetheless, the findings highlight the critical need for larger, more diverse trials to validate these therapies and explore additional treatment strategies. Future research must aim to address these evidence gaps, improving treatment efficacy and patient quality of life, particularly for males disproportionately affected by the disease.

Protocol Registration

The protocol for this systematic review is registered in the Open Science Framework (OSF): osf. io/k86ms.

Multidisciplinary and multidimensional approaches to transplantation in children with rare genetic kidney diseases

In this review, we describe the multidisciplinary, multidimensional care required to optimize outcomes for pediatric transplant recipients with rare genetic kidney diseases. Transplant success, recipient survival, and improvement in quality of life depend on collaboration between patients, families, and a team of specialists with medical, as well as nonmedical expertise. A multidisciplinary transplant team composed of experts from medicine, surgery, nursing, nutrition, social services, transplant coordination, psychology, and pharmacology, is now standard in most transplant centers and is critical to the success of a transplant. In addition to these professionals, other specialists, such as cardiologists, urologists, geneticists, metabolic disease specialists, occupational therapists, case management, child life, chaplain, and palliative care services, have a crucial role to play in the preparation, surgery, and follow-up care, especially when a pediatric patient has a rare genetic disorder leading to renal involvement, and the need for transplantation. In order to describe this multidisciplinary care, we divide the genetic renal diseases into five subgroups-metabolic and tubular disorders, glomerular diseases, congenital anomalies of the kidney and urinary tract, ciliopathies including cystic diseases, and miscellaneous renal conditions; and describe for each, the need for care beyond that provided by the standard transplant team members.

A case report of esophageal leiomyoma in Alport's syndrome treated with robotic-assisted distal myotomy: A surgical technique to avoid esophagectomy

INTRODUCTION

Alport's syndrome is the most common hereditary nephropathy, characterized by progressive renal failure, sensorineural deafness, and ocular abnormalities. It may rarely coexist with diffuse leiomyomatosis of the digestive tract, respiratory tract, or female genitalia, and in this setting, it is called Alport-leiomyomatosis syndrome. The leiomyomas most commonly affect the esophagus, and the symptoms have early onset. Treatment is usually esophagectomy.

CASE PRESENTATION

We report the case of an 8 years-old girl in which we performed a novel strategy of an esophagus-sparing approach with a robotic-assisted myotomy. This conservative approach has never been described in the literature to our knowledge.

DISCUSSION

The underpinning rationale was to resolve the patient's symptoms with partial resection of the benign tumor, avoiding an esophagectomy. Although it is likely related to a higher relapsing rate, it is more tolerable by an 8 years-old patient, and was highly effective in resolving her symptoms.

CONCLUSION

The video of a successful minimally invasive conservative approach to esophageal leiomyomatosis is presented.

Confirmation of COL4A6 variants in X-linked nonsyndromic hearing loss and its clinical implications

Hearing loss (HL) is one of the most common sensory defects, of which X-linked nonsyndromic hearing loss (NSHL) accounts for only 1-2%. While a COL4A6 variant has been reported in a single Hungarian family with NSHL associated with inner ear malformation, causative role of COL4A6 variants and their phenotypic consequences in NSHL remain elusive. Here we report two families in which we identified a male member with X-linked HL. Each has inherited a rare hemizygous COL4A6 variant from their respective mothers, NM_001287758.1: c.3272 G > C (p.Gly1091Ala) and c.951 + 1 G > C. An in vitro minigene splicing assay revealed that c.951 + 1 G > T leads to skipping of exon 15, strongly suggesting a pathogenic role for this variant in the HL phenotype. The p.Gly1091Ala variant is classified as a variant of unknown significance based on the variant interpretation guidelines. This report provides evidence for variants in the COL4A6 gene resulting in X-linked NSHL. It highlights the importance of in-depth genetic studies in all family members in addition to the proband, especially in multiplex families, to determine the precise etiology of HL.

Clinical Manifestations of Alport Syndrome-Diffuse Leiomyomatosis Patients With Contiguous Gene Deletions in COL4A6 and COL4A5

Alport syndrome-diffuse leiomyomatosis is a rare type of X-linked Alport syndrome resulting from contiguous deletions of 5′ exons of COL4A5 and COL4A6. Studies have suggested that the occurrence of diffuse leiomyomatosis is associated with the characteristic localisation of the COL4A6 gene deletion break point. An electronic database was searched for all studies accessing AS-DL to analyze the clinical characteristics, gene deletion break points of patients with AS-DL, and the pathogenesis of AS-DL. It was found that the proportion of de novo mutations of AS-DL was significantly higher in female probands than male probands (78 vs. 44%). Female patients with AS-DL had a mild clinical presentation. The incidence of proteinuria and ocular abnormalities was much lower in female probands than in male probands, and there was generally no sensorineural hearing loss or chronic kidney disease (CKD), which progressed to Stage 3 in female probands. The contiguous deletion of the 5' exons of COL4A5 and COL4A6, with the break point within the intron 3 of COL4A6, was the critical genetic defect causing AS-DL. However, the pathogenesis of characteristic deletion of COL4A6 that contributes to diffuse leiomyomatosis is still unknown. In addition, characteristic contiguous deletion of COL4A5 and COL4A6 genes in AS-DL may be related to transposed elements (TEs).

Molecular differential diagnosis of uterine leiomyomas and leiomyosarcomas

Uterine leiomyomas (LM) and leiomyosarcomas (LMS) are considered biologically unrelated tumors due to their cytogenetic and molecular disparity. Yet, these tumors share morphological and molecular characteristics that cannot be differentiated through current clinical diagnostic tests, and thus cannot be definitively classified as benign or malignant until surgery. Newer approaches are needed for the identification of these tumors, as has been done for other tissues. The application of next generation sequencing enables the detection of new mutations that, when coupled to machine learning bioinformatic tools, advances our understanding of chromosomal instability. These approaches in the context of LM and LMS could allow the discovery of genetic variants and possible genomic markers. Additionally, the potential clinical utility of circulating cell-free tumor DNA could revolutionize the noninvasive detection and monitoring of these tumors. Here, we seek to provide a perspective on the molecular background of LM and LMS, recognizing their distinct molecular features that may lead to improved diagnosis and personalized treatments, which would have a measurable impact on women's reproductive health.

Diffuse leiomyomatosis with circumferential thickening of the gastrointestinal wall, resembling human diffuse leiomyomatosis, in a young miniature dachshund

Leiomyoma is the most common mesenchymal tumor in the gastrointestinal (GI) tract. Leiomyomas usually have a single or multinodular mass of various sizes, and affected animals can develop alimentary symptoms depending on the location and size. A 3-year old female miniature dachshund died after a history of refractory rectal prolapse, esophagectasis and aspiration pneumonia. At necropsy, the GI wall at the gastroesophageal and anorectal junctions was circumferentially thickened. Histologically, both GI lesions were composed of bundles of well-differentiated smooth muscles without mass formation or invasive growth. The neoplastic cells had little cellular atypia and low proliferative activity, and were positive for α-smooth muscle actin. The lesions were diagnosed as diffuse leiomyomatosis with circumferential thickening of the GI wall and has not been described in the veterinary literature.

Alport-leiomyomatosis syndrome requiring subtotal esophagectomy for refractory gastroesophageal reflux disease after childhood partial esophagogastrectomy: a case report

Alport-leiomyomatosis syndrome is an extremely rare condition occurring at a young age in which Alport syndrome coexists with diffuse leiomyomatosis of the digestive tract (primarily the esophagus). Most patients with diffuse esophageal leiomyomatosis require esophagectomy of variable extents. A 20-year-old man with Alport-leiomyomatosis syndrome was diagnosed with dysphasia and hematuria in childhood. Although he underwent partial esophagogastrectomy at 8 years of age, extremely severe gastroesophageal reflux symptoms were noted postoperatively. He was diagnosed with refractory severe reflux esophagitis associated with diffuse leiomyomatosis and esophagogastric anastomosis, for which he underwent subtotal esophagectomy, gastric tube reconstruction, and esophagogastric anastomosis in the left neck. The postoperative course was generally good, and he had no postoperative reflux symptoms. To achieve long-term control of symptoms, the lesion must be removed completely; nevertheless, unnecessarily extensive esophagectomy should be avoided.

Genotype-phenotype correlation and prognostic impact in Chinese patients with Alport Syndrome

BACKGROUND

Alport Syndrome (AS) is a progressive hereditary glomerular disease. It is often accompanied by sensorineural hearing loss and ocular abnormalities and can sometimes develop into end stage renal disease (ESRD), which is caused by mutations in the genes encoding the collagen type IV family of proteins.

METHODS

This study analyzed the association between the clinical data of seven AS families and genes and the disease progression of different mutation types, including COL4A3 (OMIM 120070)，COL4A4 (OMIM 120131), and COL4A5 (OMIM303630).

RESULTS

A total of six new pathogenic mutation sites, one complex heterozygous mutation at COL4A3, and a combined mutation of COL4A5 and INF2 (OMIM 610982) were identified in this study. It was revealed that the clinical manifestations of X-linked AS caused by mutations in the COL4A5 gene were more severe in males than in females. In addition, the difference in patient phenotype can be attributed to the location of gene mutations affecting the protein domain or functional domain. Our data suggested that the gene deletion and nonsense mutations had a high risk for progression to ESRD.

CONCLUSION

Our results revealed the spectrum of type IV collagen genes, which contribute to the enrichment of database resources and has important implications in the diagnosis, prognosis, and guiding treatment of AS.

Uterine stem cells: from basic research to advanced cell therapies

BACKGROUND

Stem cell research in the endometrium and myometrium from animal models and humans has led to the identification of endometrial/myometrial stem cells and their niches. This basic knowledge is beginning to be translated to clinical use for incurable uterine pathologies. Additionally, the implication of bone marrow-derived stem cells (BMDSCs) in uterine physiology has opened the field for the exploration of an exogenous and autologous source of stem cells.

OBJECTIVE AND RATIONALE

In this review, we outline the progress of endometrial and myometrial stem/progenitor cells in both human and mouse models from their characterization to their clinical application, indicating roles in Asherman syndrome, atrophic endometrium and tissue engineering, among others.

SEARCH METHODS

A comprehensive search of PubMed and Google Scholar up to December 2017 was conducted to identify peer-reviewed literature related to the contribution of bone marrow, endometrial and myometrial stem cells to potential physiological regeneration as well as their implications in pathologies of the human uterus.

OUTCOMES

The discovery and main characteristics of stem cells in the murine and human endometrium and myometrium are presented together with the relevance of their niches and cross-regulation. The current state of advanced stem cell therapy using BMDSCs in the treatment of Asherman syndrome and atrophic endometrium is analyzed. In the myometrium, the understanding of genetic and epigenetic defects that result in the development of tumor-initiating cells in the myometrial stem niche and thus contribute to the growth of uterine leiomyoma is also presented. Finally, recent advances in tissue engineering based on the creation of novel three-dimensional scaffolds or decellularisation open up new perspectives for the field of uterine transplantation.

WIDER IMPLICATIONS

More than a decade after their discovery, the knowledge of uterine stem cells and their niches is crystalising into novel therapeutic approaches aiming to treat with cells those conditions that cannot be cured with drugs, particularly the currently incurable uterine pathologies. Additional work and improvements are needed, but the basis has been formed for this therapeutic application of uterine cells.

Characterization of contiguous gene deletions in COL4A6 and COL4A5 in Alport syndrome-diffuse leiomyomatosis

Alport syndrome-diffuse leiomyomatosis (AS-DL, OMIM: 308940) is a rare variant of the X-linked Alport syndrome that shows overgrowth of visceral smooth muscles in the gastrointestinal, respiratory and female reproductive tracts in addition to renal symptoms. AS-DL results from deletions that encompass the 5' ends of the COL4A5 and COL4A6 genes, but deletion breakpoints between COL4A5 and COL4A6 have been determined in only four cases. Here, we characterize deletion breakpoints in five AS-DL patients and show a contiguous COL4A6/COL4A5 deletion in each case. We also demonstrate that eight out of nine deletion alleles involved sequences homologous between COL4A5 and COL4A6. Most breakpoints took place in recognizable transposed elements, including long and short interspersed repeats, DNA transposons and long-terminal repeat retrotransposons. Because deletions involved the bidirectional promoter region in each case, we suggest that the occurrence of leiomyomatosis in AS-DL requires inactivation of both genes. Altogether, our study highlights the importance of homologous recombination involving multiple transposed elements for the development of this continuous gene syndrome and other atypical loss-of-function phenotypes.

Genomics of uterine leiomyomas: insights from high-throughput sequencing

Uterine leiomyomas are benign smooth-muscle tumors of extremely low malignant potential. Early work utilizing classical cytogenetics revealed that a subset of uterine leiomyomas harbor recurrent chromosomal rearrangements, such as translocations affecting the HMGA2 gene. Our understanding of the genetics of many tumor types has deepened remarkably with the emergence of next-generation sequencing technologies. Exome sequencing identified that the majority of leiomyomas display highly specific MED12 mutations. Further studies suggest that these MED12 hotspot mutations are also frequent in breast fibroadenomas, but not in other human tumors. Whole-genome sequencing showed that a subset of leiomyomas display complex chromosomal rearrangements resembling chromothripsis. These were formed in a single event of chromosomal breakage and random reassembly involving one or a limited number of chromosomes. Although most leiomyomas have been shown to arise independently, these studies also revealed that distinct nodules within a uterus may display identical genetic changes indicating a common clonal origin. A minority of leiomyomas were also found to display deletions within the COL4A5-COL4A6 genes, leading to upregulation of the adjacent gene IRS4. The findings derived from high-throughput sequencing combined with previous knowledge have led to an emerging molecular classification of leiomyomas, suggesting that there are several distinct pathogenic pathways involved in leiomyoma formation. The evidence points to at least 4 molecular subclasses: leiomyomas with MED12 mutation, FH inactivation, HMGA2 overexpression, and COL4A6-COL4A5 deletion. Elucidating the molecular pathogenesis of leiomyomas should be relevant for developing treatments for this very common disease.

The role of angiogenic factors in fibroid pathogenesis: potential implications for future therapy

BACKGROUND

It is well established that tumors are dependent on angiogenesis for their growth and survival. Although uterine fibroids are known to be benign tumors with reduced vascularization, recent work demonstrates that the vasculature of fibroids is grossly and microscopically abnormal. Accumulating evidence suggests that angiogenic growth factor dysregulation may be implicated in these vascular and other features of fibroid pathophysiology.

METHODS

Literature searches were performed in PubMed and Google Scholar for articles with content related to angiogenic growth factors and myometrium/leiomyoma. The findings are hereby reviewed and discussed.

RESULTS

Multiple growth factors involved in angiogenesis are differentially expressed in leiomyoma compared with myometrium. These include epidermal growth factor (EGF), heparin-binding-EGF, vascular endothelial growth factor, basic fibroblast growth factor, platelet-derived growth factor, transforming growth factor-β and adrenomedullin. An important paradox is that although leiomyoma tissues are hypoxic, leiomyoma feature down-regulation of key molecular regulators of the hypoxia response. Furthermore, the hypoxic milieu of leiomyoma may contribute to fibroid development and growth. Notably, common treatments for fibroids such as GnRH agonists and uterine artery embolization (UAE) are shown to work at least partly via anti-angiogenic mechanisms.

CONCLUSIONS

Angiogenic growth factors play an important role in mechanisms of fibroid pathophysiology, including abnormal vasculature and fibroid growth and survival. Moreover, the fibroid's abnormal vasculature together with its aberrant hypoxic and angiogenic response may make it especially vulnerable to disruption of its vascular supply, a feature which could be exploited for treatment. Further experimental studies are required in order to gain a better understanding of the growth factors that are involved in normal and pathological myometrial angiogenesis, and to assess the potential of anti-angiogenic treatment strategies for uterine fibroids.

Uterine fibroids: pathogenesis and interactions with endometrium and endomyometrial junction

Uterine leiomyomas (fibroids or myomas) are benign tumors of uterus and clinically apparent in a large part of reproductive aged women. Clinically, they present with a variety of symptoms: excessive menstrual bleeding, dysmenorrhoea and intermenstrual bleeding, chronic pelvic pain, and pressure symptoms such as a sensation of bloatedness, increased urinary frequency, and bowel disturbance. In addition, they may compromise reproductive functions, possibly contributing to subfertility, early pregnancy loss, and later pregnancy complications. Despite the prevalence of this condition, myoma research is underfunded compared to other nonmalignant diseases. To date, several pathogenetic factors such as genetics, microRNA, steroids, growth factors, cytokines, chemokines, and extracellular matrix components have been implicated in the development and growth of leiomyoma. This paper summarizes the available literature regarding the ultimate relative knowledge on pathogenesis of uterine fibroids and their interactions with endometrium and subendometrial myometrium.

Alport syndrome--insights from basic and clinical research

In 1927, Arthur C. Alport first published his description of a triad of symptoms in a family with hereditary congenital haemorrhagic nephritis, deafness and ocular changes. A few years after his death, this group of symptoms was renamed Alport syndrome. To this day, Alport syndrome still inevitably leads to end-stage renal disease and the need for renal replacement therapy, starting in young adulthood. During the past two decades, research into this rare disease has focused on the effects of mutations in collagen type IV and the role of changes in podocytes and the glomerular basement membrane that lead to early kidney fibrosis. Animal models of Alport syndrome also demonstrate the pathogenetic importance of interactions between podocytes and the extracellular matrix. Such models might also help researchers to answer basic questions about podocyte function and the development of fibrosis, and to develop new therapeutic approaches that might be of use in other kidney diseases. In this Review, we discuss the latest basic and clinical research on Alport syndrome, focusing on the roles of podocyte pathology and the extracellular matrix. We also highlight early diagnosis and treatment options for young patients with this disorder.

Leiomyoma: genetics, assisted reproduction, pregnancy and therapeutic advances

PURPOSE

Uterine leiomyomas are common, benign, reproductive tract tumors affecting a majority of reproductive aged women. They are associated with gynecologic morbidity and detrimentally affect reproductive potential. The etiology of leiomyomas is poorly understood and their diagnosis prior to treatment with Assisted Reproductive Technologies (ART) represents a management dilemma. The purpose of this paper is to review known genetic and molecular contributions to the etiologies of leiomyomas, describe their impact on ART outcomes and reproductive potential, and review alternative therapies and future directions in management.

METHODS

A critical review of the literature pertaining to genetic component of uterine leiomyomas, their impact on ART and pregnancy and leiomyoma therapeutics was performed.

RESULTS

Uterine leiomyomas are characterized by complex molecular mechanisms. Their location and size determines their potential detriment to ART and reproductive function and novel therapeutic modalities are being developed.

CONCLUSION

The high prevalence of uterine leiomyomas and their potential detrimental influence on ART and reproductive function warrants continued well-designed studies to ascertain their etiology, optimal treatment and novel less morbid therapies.