Fenotipos inesperados en el síndrome de Alport: la necesidad del estudio genético / Unexpected phenotypes in Alport syndrome: the need for genetic testing

El diagnóstico del síndrome de Alport supone un reto en la edadpediátrica, debido a la ausencia de fenotipos clínicos esperados de la enfermedad, su clásica caracterización de entidad rara y la práctica muy restringida de biopsias renales con análisis rutinario de la muestra por microscopía electrónica durante la infancia. Se presentan las características clínicas y genéticas de 6 pacientes pediátricos (4 mujeres) diagnosticados de síndromede Alport en dos centros hospitalarios entre 2018 y 2021. Todos los pacientes presentaron un debut clínico claramente diferente y ninguno presentó complicaciones auditivas nioftalmológicas. La mitad carecía de antecedentes familiares de enfermedad renal crónica. Ninguna biopsia renal realizada confirmó el diagnóstico. Todos los pacientes fueron confirmadosgenéticamente y fueron el caso índice del estudio familiar. Esta serie ilustra la presencia de fenotipos clínicos inesperados en el síndrome de Alport y refleja la necesidad de incorporar el estudio genético para su diagnóstico.

The diagnosis of Alport syndrome is a challenge in the pediatric age, due to the absence of expected clinical phenotypes of the disease, its classic characterization of a rare disease and the very restricted practice of renal biopsies with routine analysis of the sample by electron microscopy during infancy. The clinical and genetic characteristics of 6 pediatric patients (4 women) diagnosed with Alport syndrome in two hospital centers between 2018 and 2021 are reported. All patients presented a clearly different clinical debut and none presented auditory or ophthalmological complications. Half had no family history of chronic kidney disease. No kidney biopsy performed confirmed the diagnosis. All patients were genetically confirmed and were the index case in the family study. This series illustrates the presence of unexpected clinical phenotypes in Alport syndrome and reflects the need for the incorporation of the genetic study for its diagnosis.

Genetic and clinical analysis of a pedigree affected with X-linked dominant Alport syndrome due to a novel variant of COL4A5 gene / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a Chinese pedigree affected with X-linked hereditary Alport syndrome.@*METHODS@#Next generation sequencing was carried out for the pedigree. Candidate variant was validated by Sanger sequencing. Pathological changes of renal basement membrane and expression of COL4A5 protein were analyzed by renal biopsy and immunofluorescence assay, respectively.@*RESULTS@#All patients from the pedigree manifested progressive renal damage, gross hematuria, proteinuria and nephrotic syndrome. Renal biopsy of the proband revealed thickening of the basement membrane. No expression of the COL4A5 gene was detected by immunofluorescence. High-throughput sequencing and Sanger sequencing indicated that the proband has carried a c.3706delC (p.1236Pfs*69) variant in exon 41 of the COL4A5 gene. The same variant was also found in his mother and two brothers whom were similarly affected.@*CONCLUSION@#The novel c.3706delC (p.1236Pfs*69) variant of the COL4A5 gene probably underlay the pathogenesis of X-linked hereditary Alport syndrome in this pedigree. Above findings have enriched the spectrum of COL4A5 gene variants and provided a basis for the diagnosis and genetic counseling for the pedigree.

Analysis of genetic variant in a child with autosomal recessive Alport syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a pedigree affected with Alport syndrome.@*METHODS@#Next generation sequencing and Sanger sequencing was applied to detect potential variants of the COL4A3, COL4A4 and COL4A5 genes among members from the pedigree and 100 unrelated healthy controls.@*RESULTS@#The proband and his twin brother were found to carry two novel variants, namely c.4953G>A and c.4623C>A, of the COL4A4 gene, which were respectively inherited from her father and mother. The same variants were not detected among the 100 healthy controls and medical literature. Based on the guidelines of the American College of Medical Genetics and Genomics, both the c.4953G>A and c.4623C>A variants were predicted to be pathogenic (PVS1+PM2_supporting+PP1).@*CONCLUSION@#The c.4953G>A and c.4623C>A variants of the COLA4A gene probably underlay the Alport syndrome in this pedigree. Above finding has enriched the spectrum of COLA4A gene variants.

Una nueva variante del gen COL4A4 (c.1856G> A). De un caso de glomeruloesclerosis focal y segmentaria a una familia con síndrome de Alport / A novel COL4A4 gene variant (c.1856G>A): from a focal segmental glomerulosclerosis case to a family with Alport syndrome

El síndrome de Alport (SA), también conocido como nefritis hereditaria, es una forma progresiva hereditaria de enfermedad glomerular que a menudo se asocia con pérdida auditiva neurosensorial y anomalías oculares. Es causada por mutaciones en los genes que codifican varios miembros de las proteínas de colágeno del tipo IV, que se hallan en las membranas basales principalmente. Los análisis genéticos de las familias afectadas han identificado cuatro modos diferentes de transmisión en pacientes con síndrome de Alport. La forma del síndrome ligada al X surge a partir de mutaciones de COL4A5 y COL4A6 en el cromosoma X, mientras que las formas autosómicas resutan de defectos genéticos tanto en el gen COL4A3 como en el COL4A4, en el cromosoma 2q35-37. Las formas digénicas incluyen pacientes con mutaciones coexistentes en COL4A3, COL4A4 y COL4A5. El resultado clínico a largo plazo en pacientes con SA con mutaciones heterocigotas de COL4A3/A4es generalmente impredecible. La glomeruloesclerosis focal y segmentaria suele desarrollarse en el SA clásico en etapas posteriores y se presenta predominantemente con proteinuria asociada con hematuria. En el caso índice presentado en este informe, a un hombre de 26 años se le realizó una biopsia de riñón debido a una proteinuria nefrótica y una hematuria microscópica acompañada de una función renal alterada. Se le diagnosticó glomeruloesclerosis focal y segmentaria. Debido a que tenía una pérdida auditiva progresiva desde el inicio del estudio, se le realizó un estudio genético de mutaciones en los genes COL4A3 y COL4A4. Se detectó una nueva mutación en el gen COL4A4 (c.1804-7T> C).Debido a que sus padres tenían un matrimonio consanguíneo, el resto de la familia fue sometida a estudio para la misma variante. Sus padres y su hermana fueron heterocigotos y homocigota para la misma variante, respectivamente. En este estudio, se demostró la existencia de una familia con síndrome de Alport con una nueva mutación en el gen COL4A4 (c.1856G> A) que, según sabemos, es el primer caso reportado.

Alport syndrome, also known as hereditary nephritis, is an inherited progressive form of glomerular disease that is often associated with sensorineural hearing loss and ocular abnormalities. It is caused by mutations in genes encoding several members of type IV colagen proteins primarily found in basement membranes. Genetic analyses of affected families have identified four different modes of transmission in patients with Alport syndrome. X-linked form of the syndrome arises from mutations of COL4A5 and COL4A6 on chromosome X, whereas autosomal forms result from genetic defects in either the COL4A3 or COL4A4 genes at chromosome 2q35-37. Digenic forms include patients with coexisting mutations in COL4A3, COL4A4, and COL4A5. The long-term clinical outcome in AS patients with heterozygous COL4A3/A4 mutations is generally unpredictable. Focal segmental glomerulosclerosis usually develops in classical AS at later stages and presents predominantly with proteinuria associated with hematuria. The index case presented in this report, a 26-year-old man, had kidney biopsy because of nephrotic proteinuria and microscopic hematuria accompanied by impaired renal function. He diagnosed focal segmental glomerulosclerosis. As he had progressive hearing loss since chidhood we conducted a genetic study for mutations in COL4A3 and COL4A4 genes. A novel mutation in COL4A4 gene (c.1804-7T>C) was detected. As his parents had consanguineous marriage we investigated the rest of the family for the same variant. His parents, and his sister were found to be heterozygote, and homozygote for the same variant, respectively. In this report we demonstrated an Alport syndrome family with a novel mutation in COL4A4 gene (c.1856G>A) that has been first reported to our best knowledge.

Posterior polymorphous corneal dystrophy in X linked Alport syndrome / Distrofia corneana polimorfa posterior em Síndrome de Alport

ABSTRACT We describe a six-year-old boy with a history of hematuria, posterior polymorphous corneal dystrophy and dots and fleck retinopathy. Alport syndrome should be ruled out in patients presenting with posterior polymorphous corneal dystrophy or anterior lenticonus and a family history of renal disease.

RESUMO Descrevemos um paciente de 6 anos de idade com história de hematúria, distrofia corneana polimorfa posterior e retinopatia em "dots and flecks". Síndrome de Alport deve ser excluída se o paciente apresentar com distrofia corneana polimorfa posterior ou lenticone anterior com historia familiar de doença renal.

Dados clínicos e da audição em indivíduos com Síndrome de Alport / Clinical data and hearing of individuals with Alport syndrome

A Síndrome de Alport (SA) é uma desordem hereditária, caracterizada por nefropatia, muitas vezes, com perda auditiva sensorioneural e com defeitos oculares. OBJETIVO: Analisar os dados clínicos e da audição em indivíduos com SA, com ênfase na correlação entre alteração renal e perda auditiva (PA). FORMA DE ESTUDO: clínico prospectivo com coorte transversal. CASUÍSTICA E MÉTODO: 37 indivíduos realizaram avaliação otorrinolaringológica e testes audiológicos. Foram considerados para a análise estatística da PA os resultados das audiometrias de tons puros. RESULTADOS: Nos 28 indivíduos que apresentavam alterações clínicas foram encontrados 46,4 por cento de DLX e 53,6 por cento de AD. A PA ocorreu em 46,1 por cento dos avaliados. 12 pacientes tinham PA no exame audiométrico 11,5 por cento, leve e 34,6 por cento, moderada. Comparados os familiares normais aos que tinham alteração renal, todos os que apresentavam PA mostravam comprometimento renal. Em 30,8 por cento a configuração era descendente suave em agudos e em 11,5 por cento era plana. CONCLUSÕES: A distribuição dos padrões de herança não coincide com o descrito na literatura. A PA é um achado extra-renal freqüente. Existe associação entre acometimento renal e PA (p= 0,009). As configurações mais freqüentes foram: descendente suave em agudos e plana. Não há associação entre a PA e a idade. Não existe correlação entre PA e sexo neste grupo.

Alport Syndrome (AS) is a hereditary disease, characterized by nephropathy, often times with sensorineural hearing loss and ocular defects. AIM: to analyze the clinical and hearing information from individuals with AS, more specifically the correlation between renal disorder and hearing loss (HL). STUDY DESIGN: clinical prospective with cross-sectional cohort. MATERIALS AND METHODS: 37 individuals underwent otorhinolaryngological evaluation and were submitted to audiologic tests. For HL statistical analysis we considered only the results from the pure tone audiometries. RESULTS: of the 28 individuals with clinical alterations, we found 46.4 percent of DLX and 53.6 percent of AD. HL happened to 46.1 percent of the individuals evaluated. 12 patients presented HL in the audiometric test: 11.5 percent mild and 34.6 percent moderate. Comparing the normal relatives with those with renal disorder; all that had HL also had renal disorder. In 30.8 percent the curve shape was mild descending in the high frequencies and in 11.5 percent it was flat. CONCLUSIONS: The inheritance pattern distribution does not match literature descriptions. HL is a frequent extra-renal finding. There is an association between renal involvement and HL (p= 0.009). The most frequent curve shapes: mild descending in the high frequencies and flat. There was no association between HL and age. There is no correlation between the HL and gender in this group.

Revisão sobre a perda auditiva na Síndrome de Alport, analisando os aspectos clínicos, genéticos e biomoleculares / Revision about hearing loss in the Alport's syndrome, analyzing the clinical, genetic and bio-molecular aspects

A Síndrome de Alport é uma desordem hereditária, caracterizada por hematúria, freqüentemente levando à falência renal. Pode ser acompanhada de alterações extra-renais, tais como: perda auditiva (PA) sensório-neural e alterações oculares. São descritas formas dominantes ligadas ao X, devidas às mutações no lócus COL4A5 e uma forma autossômica recessiva resultando de mutações no lócus COL4A3 ou COL4A4. Ainda foi sugerido um tipo autossômico dominante de SA. A doença decorre de alterações nas cadeias de colágeno tipo IV e os sintomas refletem o comprometimento da membrana basal de vários órgãos. As redes a3.a4.a5(IV) ocorrem no rim, na cóclea e no olho. O objetivo foi caracterizar a PA neste grupo de pacientes. Quando o quadro progride para o estágio final de falência renal, o melhor método de tratamento é o transplante, que tem contribuído para o aumento da sobrevida. Nesta revisão bibliográfica, observamos que: 1. A SA caracteriza-se por hematúria, que evolui para falência renal e pode ser acompanhada de manifestações extra-renais. A PA é um achado extra-renal freqüente e um dos primeiros sintomas na SA, sendo um fator relevante para o prognóstico da evolução da doença renal; 2. A SA é genética e decorre da alteração das cadeias do colágeno tipo IV nas membranas basais; 3. A perda auditiva na SA é sensório-neural, de intensidade variável, progressiva e simétrica. Acomete as freqüências médias e altas; 4. Na investigação das perdas auditivas, o torrinolaringologista deve incluir um exame de urina. É fundamental que o otologista atue no acompanhamento deste grupo de pacientes.

Alport Syndrome is a genetic disorder characterized by hematuria, which often leads to renal failure. It may also be accompanied by extra-renal alterations, such as: sensorineural hearing loss, and ocular abnormalities. Dominant forms related to the X chromosome and caused by mutations in the locus COL4A5 have been described, as well as an autossomic recessive form resulting from mutations in the locus COL4A3 or COL4A4. An autossomic dominant type of AS has also been reported. The disease is caused by changes in the collagen type IV chains, where symptoms reflect the damage to the basal membrane of several organs. The alpha3.alpha4.alpha5(IV) networks are found in the kidneys, cochlea and eyes. The objective was to characterize AS in this group of patients. In the current literature review it was found that: 1. AS is characterized by hematuria that may develop into renal failure and can also be accompanied by extra-renal manifestations. Hearing loss is a frequent extra-renal finding and one of the first symptoms of AS, therefore representing a relevant factor in the prognosis of the renal disease; 2. It is a genetic disorder resulting from abnormalities in the chains of collagen type IV in the basal membranes; 3. The hearing loss in AS is typically sensorineural with variable intensities, progressive and symmetrical, affecting middle and high frequencies; 4. Otolaryngologists should include a urine test in the SNHL work-up. It is essential to have an otologist involved in the treatment of these patients.

Anterior Lens Capsule Abnormalities in Alport Syndrome

Alport syndrome is a hereditary, progressive disease characterized by progressive nephritis, sensorineural deafness, and ocular abnormalities, including anterior lenticonus. The ultrastructure of the lens capsule abnormalities in Alport syndrome is reported. Four anterior lens capsules from 31-year-old patient and 26-year-old patient with lenticonus who were affected by the Alport syndrome were obtained at capsulectomy. And all four anterior lens capsules were examined by transmission electron microscopy. The histopathologic findings showed that the thickness of the anterior lens capsules was decreased (4~13 micrometer) and that there were many vascular dehiscences localized at the inner part of the lens capsule. There were large numbers of capsular dehiscences containing fibrillar materials and vacuoles. The anterior capsules were clearly fragile in this disease, forming the basis for the progressive lenticonus and anterior polar cataract.

Síndrome de Alport: estudo de uma família / Alport's syndrome: a family study

Objetivo: A síndrome de Alport caracteriza-se por nefropatia hereditária, geralmente associada à surdez neurossensorial (Alport, 1927) e alteraçöes oculares (Sohar, 1954). Estudaram-se as manifestaçöes da síndrome em membros de uma mesma família, considerando aspectos clínicos e genéticos. Pacientes e método: Foram submetidos a exame oftalmológico quinze indivíduos de uma família, dos quais quatro apresentavam síndrome de Alport. Os exames foram realizados na Clínica Oftalmológica do Hospital Getúlio Vargas - Universidade Federal do Piauí (HGV/UFPI). Resultados: Revelaram-se quatro indivíduos afetados pela síndrome de Alport, dos quais três apresentavam surdez moderada, lenticone anterior bilateral e nefropatia crônica, e um tinha manifestaçäo renal isolada. Todos os pacientes eram brancos, do sexo masculino, com idade entre 12 e 25 anos. Acuidade visual dos olhos com lenticone variou de 20/50 a 20/100. Conclusöes: A análise da família identificou três casos confirmados e um suspeito, sugerindo padräo de herança recessiva ligada ao X, näo sendo possível afastar a herança autossômica dominante com penetrância incompleta.

Alport's syndrome, an undiagnosed entity with different modes of inheritance and review of literature

We report here three cases of presumed Alport's Syndrome from different families presenting with mild to moderate renal failure. Two of these were teenage girls, while the third was a teenage boy. We confirmed positive family history in all cases and the mode of inheritance seemed to be Autosomal dominant, X-linked and Autosomal recessive among the three families. Sensori-neural deafness and bilateral anterior lenticonus was found in all of them. Renal biopsy was done in two cases. Histopathological changes on light microscopy were suggestive of Alport's syndrome. Electrone microscopy could not be done due to lack of facilities. Family counseling had a little impact, as apparently health family members declined to undergo screening procedures due to apprehension of having the similar disease. Hemodialysis is well-tolerated and kidney transplantation prolong renal and patient's survival. This paper highlights the fact that the condition is rather under diagnosed in our population and needs to be considered where appropriate

Síndrome de Alport: nefropatía hereditaria progresiva / Alport's syndrome: progressive hereditary nephropathy

El síndrome de Alport es una enfermedad hereditaria que se caracteriza por una nefropatía hematúrica, progresiva, que evoluciona hacia la insuficiencia renal y se acompaña de hipoacusia bilateral de tipo neurosensorial. Se presentan tres pacientes relacionados entre sí, de 9,7 y 5 años de edad, del mismo núcleo familiar, con historia familiar de sordera, enfermedad renal y fallecimiento por uremia. Los tres pacientes tienen hematuria recurrente y proteinuria de grado variable. Todos tienen disminución de la ecogenicidad del parenquina renal con evaluación oftalmológica, inmunológica y tiroidea normales. La presencia del síndrome de Alport debe ser sospechada ante un niño o adulto joven con hematuria persistente sin causa aparente y prestar asesoramiento genético a las personas de alto riesgo

Asociación de criptorquidismo con nefritis hereditaria: estudio de tres generaciones de una familia puertorriqueña / Cryptorchidism associated with hereditary nephritis: a 3-generation study in a Puerto Rican family

Veintitrés miembros de una familia afectada por nefritis familiar fueron estudiados a lo largo de tres generaciones. La incidencia de manifestaciones auditivas, oculares y hematológicas fue baja. Se encontró que cuatro de los pacientes del sexo masculino con nefritis también presentaron criptorquidismo. En este reporte documentamos la ocurrencia no previamente registrada de criptorquidismo en asociación con la enfermedad de Alport. Se describen las características de la enfermedad en esta familia y se ofrece un repaso de la literatura sobre el tema

Manifestaciones oftalmológicas del síndrome de Alport / Ophthalmologics manifestations of Alport's syndrome

Se presenta un caso de síndrome de Alport, con presencia de lenticono anterior, retinitis pigmentosa atípica y sordera, con biopsia renal característica de nefritis hereditaria. Se discuten las características clínicas del síndrome, con énfasis en las manifestaciones oculares