Revisão sobre a perda auditiva na Síndrome de Alport, analisando os aspectos clínicos, genéticos e biomoleculares

A founder COL4A3 pathogenic variant resulting in Alport syndrome and thin basement membrane disease: a case report series

Alport syndrome is a rare genetic condition characterized by kidney disease, hearing impairment, and ocular abnormalities. It exhibits various inheritance patterns involving pathogenic variants in COL4A3, COL4A4, and COL4A5 genes. The phenotypes can range from isolated hematuria with a non-progressive or very slowly progressive course to progressive kidney disease with extrarenal abnormalities. Timely diagnosis of Alport syndrome facilitates the early and effective implementation of treatment, as well as genetic counseling. Here, we report the COL4A3 c.765G > A, p.((=)) mutation in three ethnically Azerbaijani, apparently unrelated, consanguineous families from the village of Algeti in the Marneuli region of Georgia. We speculate that this variant could represent a founder mutation within this population and recommend offering genetic testing to Algeti village residents with persistent hematuria.

Management of Hematuria in Children

Purpose of Review

This paper provides a review of the diagnostic evaluation of both microscopic and gross hematuria, as well as an update on the pathogenesis, clinical features, and treatment strategies for several diseases of the kidneys and urinary tract in which hematuria is a prominent finding. The goal is to provide pediatric providers with a framework through which appropriate and expeditious referral to subspecialty care may be made for definitive treatment.

Recent Findings

Although there has been great heterogeneity in published treatment strategies for many causes of hematuria, the Kidney Diseases Improving Global Outcomes (KDIGO) initiative has recently set forth guidelines for glomerular diseases in particular to provide evidence-based strategies for treatment. In addition, recent advances in the understanding of molecular pathogenesis and long-term clinical outcomes for other non-glomerular diseases has led to updates in treatment strategies summarized in this review.

Summary

As the pediatric primary care provider is often the first point of contact for children with microscopic or gross hematuria, updated knowledge as to the epidemiology and management of several of the various causes of hematuria will improve the care of children by both avoiding extraneous testing and interventions and implementing definitive care (either by expectant management and reassurance or by subspecialty referral) in a timely manner.

Achados audiológicos em pacientes submetidos ao transplante renal

OBJETIVO: Investigar o comportamento auditivo de pacientes com insuficiência renal crônica submetidos ao transplante renal. MÉTODOS: Foram avaliados 30 pacientes, 10 do gênero feminino e 20 do gênero masculino, na faixa etária de 13 a 26 anos (média de idade 16,97 anos). Os sujeitos foram submetidos a anamnese, avaliação otorrinolaringológica, avaliação audiológica convencional e de altas frequências, medidas de imitância acústica e avaliação do processamento auditivo central. Para os resultados da audiometria de altas frequências foi utilizado um grupo controle. RESULTADOS: Os sujeitos não apresentaram queixas auditivas na anamnese. Os resultados da audiometria convencional demonstraram predomínio da normalidade; na audiometria de altas frequências, os pacientes apresentaram resultados piores do que os sujeitos do grupo controle. Na imitanciometria houve predomínio de curva tipo A bilateral. Na avaliação do processamento auditivo central, 14 sujeitos (46,67%) apresentaram resultados alterados no Staggered Spondaic Word Test (SSW). Houve diferença significativa entre a variável idade e o resultado da audiometria tonal limiar: quanto maior a idade, menor a sensibilidade auditiva nos limiares de 250 Hz a 8 kHz. Houve relação entre o tipo de doador (cadáver ou vivo) e o resultado do teste SSW: os índices de resultados alterados foram maiores quando o doador era cadáver, em comparação com casos de doador vivo. CONCLUSÃO: Houve alterações na avaliação audiológica convencional e de altas frequências e no processamento auditivo central de sujeitos com insuficiência renal crônica submetidos ao transplante renal, sugerindo a necessidade de orientação à equipe envolvida quanto aos cuidados, prevenção e identificação precoce de acometimentos audiológicos.

Severe to profound hearing loss in patients with progressed Alport's syndrome

CONCLUSION

The concept of hearing loss severity must be redefined, as there is a clear need for more active hearing management in Alport's syndrome patients with severe and profound hearing loss.

OBJECTIVES

Sensorineural hearing loss (SNHL) caused by Alport's syndrome generally does not exceed 60-70 dB, because a cochlear lesion is responsible for this hearing loss. Careful management of renal function improves the prognosis and the longevity of Alport's syndrome patients; it is useful to reassess SNHL caused by Alport's syndrome.

PATIENTS AND METHODS

Thirty-two patients with Alport's syndrome were analyzed retrospectively. Pure tone audiograms (PTAs), speech audiograms, and transiently evoked otoacoustic emissions (TEOAEs) were performed. Hearing loss severity was compared to duration of disease and severity of renal dysfunction. We also evaluated the correlation between OAEs and PTAs according to the hypothesis that evoked OAEs would be abnormal even in early stage SNHL in Alport's syndrome.

RESULTS

The level of hearing was positively correlated with disease duration. The hearing of the end-stage renal disease (ESRD) group, whose hearing threshold could exceed 70 dB, was worse than that of the non-ESRD group. OAEs were found in patients with normal hearing and mild hearing loss and had no significant early detection value.

Inner ear defects and hearing loss in mice lacking the collagen receptor DDR1

Discoidin domain receptor 1 (DDR1) is a tyrosine kinase receptor that is activated by native collagen. The physiological functions of DDR1 include matrix homeostasis and cell growth, adhesion, branching, and migration, but the specific role of DDR1 in the development and function of the inner ear has not been analyzed. Here, we show that deletion of the DDR1 gene in mouse is associated with a severe decrease in auditory function and substantial structural alterations in the inner ear. Immunohistochemical analysis demonstrated DDR1 expression in several locations in the cochlea, mostly associated with basement membrane and fibrillar collagens; in particular in basal cells of the stria vascularis, type III fibrocytes, and cells lining the basilar membrane of the organ of Corti. In the stria vascularis, loss of DDR1 function resulted in altered morphology of the basal cells and accumulation of electron-dense matrix within the strial epithelial layer in conjunction with a focal and progressive deterioration of strial cells. Cell types in proximity to the basilar membrane, such as Claudius', inner and outer sulcus cells, also showed marked ultrastructural alterations. Changes in the organ of Corti, such as deterioration of the supporting cells, specifically the outer hair cells, Deiters', Hensen's and bordering cells, are likely to interfere with mechanical properties of the organ and may be responsible for the hearing loss observed in DDR1-null mice. These findings may also have relevance to the role of DDR1 in other disease processes, for example, those affecting the kidney.