RESUMEN
Surfactant protein B encoding gene mutations have been related to early onset fatal respiratory distress in full-term neonates. We report a school-aged male child homozygous for a surfactant protein B encoding gene missense mutation who presented after the neonatal period. His respiratory insufficiency responded to high dose intravenous methylprednisolone and hydroxychloroquine.
Asunto(s)
Diagnóstico Tardío , Proteinosis Alveolar Pulmonar/congénito , Proteína B Asociada a Surfactante Pulmonar/deficiencia , Niño , Marcadores Genéticos , Homocigoto , Humanos , Masculino , Mutación , Proteinosis Alveolar Pulmonar/diagnóstico , Proteinosis Alveolar Pulmonar/genética , Proteinosis Alveolar Pulmonar/terapia , Proteína B Asociada a Surfactante Pulmonar/genéticaRESUMEN
Pulmonary surfactant is a substance composed of a lipoprotein complex that is essential to pulmonary function. Pulmonary surfactant proteins play an important role in the structure, function, and metabolism of surfactant; 4 specific surfactant proteins have been identified: surfactant proteins-A, surfactant proteins-B, surfactant proteins-C, and surfactant proteins-D. Clinical, epidemiological, and biochemical evidence suggests that the etiology of respiratory distress syndrome is multifactorial with a significant genetic component. There are reports about polymorphisms and mutations on the surfactant protein genes, especially surfactant proteins-B, that may be associated with respiratory distress syndrome, acute respiratory distress syndrome, and congenital alveolar proteinosis. Individual differences regarding respiratory distress syndrome and acute respiratory distress syndrome as well as patient response to therapy might reflect phenotypic diversity due to genetic variation, in part. The study of the differences between the allelic variants of the surfactant protein genes can contribute to the understanding of individual susceptibility to the development of several pulmonary diseases. The identification of the polymorphisms and mutations that are indeed important for the pathogenesis of the diseases related to surfactant protein dysfunction, leading to the possibility of genotyping individuals at increased risk, constitutes a new research field. In the future, findings in these endeavors may enable more effective genetic counseling as well as the development of prophylactic and therapeutic strategies that would provide a real impact on the management of newborns with respiratory distress syndrome and other pulmonary diseases.
Asunto(s)
Mutación , Proteínas Asociadas a Surfactante Pulmonar/genética , Surfactantes Pulmonares/metabolismo , Síndrome de Dificultad Respiratoria del Recién Nacido/genética , Predisposición Genética a la Enfermedad , Variación Genética , Humanos , Recién Nacido , Polimorfismo Genético , Proteinosis Alveolar Pulmonar/genética , Proteinosis Alveolar Pulmonar/metabolismo , Proteína A Asociada a Surfactante Pulmonar/deficiencia , Proteína B Asociada a Surfactante Pulmonar/deficiencia , Proteína C Asociada a Surfactante Pulmonar/deficiencia , Proteína D Asociada a Surfactante Pulmonar/deficiencia , Proteínas Asociadas a Surfactante Pulmonar/metabolismo , Síndrome de Dificultad Respiratoria del Recién Nacido/metabolismoRESUMEN
Pulmonary surfactant is a substance composed of a lipoprotein complex that is essential to pulmonary function. Pulmonary surfactant proteins play an important role in the structure, function, and metabolism of surfactant; 4 specific surfactant proteins have been identified: surfactant proteins-A, surfactant proteins-B, surfactant proteins-C, and surfactant proteins-D. Clinical, epidemiological, and biochemical evidence suggests that the etiology of respiratory distress syndrome is multifactorial with a significant genetic component. There are reports about polymorphisms and mutations on the surfactant protein genes, especially surfactant proteins-B, that may be associated with respiratory distress syndrome, acute respiratory distress syndrome, and congenital alveolar proteinosis. Individual differences regarding respiratory distress syndrome and acute respiratory distress syndrome as well as patient response to therapy might reflect phenotypic diversity due to genetic variation, in part. The study of the differences between the allelic variants of the surfactant protein genes can contribute to the understanding of individual susceptibility to the development of several pulmonary diseases. The identification of the polymorphisms and mutations that are indeed important for the pathogenesis of the diseases related to surfactant protein dysfunction, leading to the possibility of genotyping individuals at increased risk, constitutes a new research field. In the future, findings in these endeavors may enable more effective genetic counseling as well as the development of prophylactic and therapeutic strategies that would provide a real impact on the management of newborns with respiratory distress syndrome and other pulmonary diseases.
O surfactante pulmonar é uma substância composta por um complexo lipoprotéico essencial para a função pulmonar normal. As proteínas do surfactante têm importante papel na estrutura, função e metabolismo do surfactante. São descritas quatro proteínas específicas denominadas surfactante pulmonar-A, surfactante pulmonar-B, surfactante pulmonar-C e surfactante pulmonar-D. Evidências clínicas, epidemiológicas e bioquímicas sugerem que a etiologia da síndrome do desconforto respiratório é multifatorial com um componente genético significativo. Existem na literatura algumas descrições sobre a presença de polimorfismos e mutações em genes dos componentes do surfactante, particularmente no gene da surfactante pulmonar-B, os quais parecem estar associados à síndrome do desconforto respiratório, síndrome da angustia respiratória aguda e proteinose alveolar congênita. Diferenças individuais relacionadas à síndrome do desconforto respiratórioe síndrome da angustia respiratória aguda e à resposta dos pacientes ao tratamento podem refletir diversidade fenotípica, devido, parcialmente, à variação genética. O estudo das diferenças entre as variantes alélicas dos genes das proteínas do surfactante pode ajudar na compreensão das variabilidades individuais na susceptibilidade ao desenvolvimento de várias doenças pulmonares. A determinação de quais polimorfismos e mutações são, de fato, importantes na patogênese das doenças relacionadas à disfunção das proteínas do surfactante e a possibilidade da realização da genotipagem em indivíduos de alto risco constitui um novo campo de pesquisa, que pode permitir, futuramente, um aconselhamento genético mais efetivo, resultando no desenvolvimento de estratégias profiláticas e terapêuticas que representem um impacto real no manejo dos recém-nascidos portadores da síndrome do desconforto respiratório e outras patologias pulmonares.
Asunto(s)
Humanos , Recién Nacido , Mutación , Proteínas Asociadas a Surfactante Pulmonar/genética , Surfactantes Pulmonares/metabolismo , Síndrome de Dificultad Respiratoria del Recién Nacido/genética , Predisposición Genética a la Enfermedad , Variación Genética , Polimorfismo Genético , Proteinosis Alveolar Pulmonar/genética , Proteinosis Alveolar Pulmonar/metabolismo , Proteína A Asociada a Surfactante Pulmonar/deficiencia , Proteína B Asociada a Surfactante Pulmonar/deficiencia , Proteína C Asociada a Surfactante Pulmonar/deficiencia , Proteína D Asociada a Surfactante Pulmonar/deficiencia , Proteínas Asociadas a Surfactante Pulmonar/metabolismo , Síndrome de Dificultad Respiratoria del Recién Nacido/metabolismoRESUMEN
Congenital alveolar proteinosis (CAP) is an often fatal cause of respiratory failure in term newborn infants, which has been associated with a genetic deficiency of surfactant protein B (SP-B) as a result of a frameshift mutation (121ins2) in a family with three affected siblings. In the index cases the deficiency of SP-B was associated with qualitative and quantitative abnormalities of the surfactant proteins A and C. Immunostaining for lung surfactant proteins and a search for the 121ins2 mutation by restriction enzyme analysis of DNA extracted from paraffin-embedded lung tissue was performed for 7 additional affected infants from 6 families, bringing to 10 the total number of patients with CAP who have been studied. In six infants, the surfactant protein immunostaining pattern was similar to that of the index cases. Of these, three patients were homozygous for the 121ins2 mutation; one was a compound heterozygote with the 121ins2 in one allele and a different mutation in the other; and three patients lacked the mutation in both alleles. One infant had an abundance of SP-B, suggesting phenotypic heterogeneity in CAP. Lung ultrastructural abnormalities, such as a reduced number of lamellar bodies, absent tubular myelin, and basal secretion of surfactant lipids and proteins, suggest a significant derangement of surfactant metabolism. The phenotypic heterogeneity in infants with CAP raises the possibility that variable degrees of SP-B deficiency may be more common than previously suspected.