RESUMO
IFN-gammaR1 deficiency is a genetic etiology of Mendelian susceptibility to mycobacterial diseases, and includes two forms of complete recessive deficiency, with or without cell surface expression, and two forms of partial deficiency, dominant or recessive. We report here a novel form of partial and recessive Interferon gamma receptor 1 (IFN-gammaR1) deficiency, which is almost as severe as complete deficiency. The patient is homozygous for a mutation of the initiation codon (M1K). No detectable expression and function of IFN-gammaR1 were found in the patient's fibroblasts. However, IFN-gammaR1 expression was found to be impaired, but not abolished, on the EBV-transformed B cells, which could respond weakly to IFN-gamma. The mechanism underlying this weak expression involves leaky translation initiation at both non-AUG codons and the third AUG codon at position 19. It results in the residual expression of IFN-gammaR1 protein of normal molecular weight and function. The residual IFN-gamma signaling documented in this novel form of partial IFN-gammaR1 deficiency was not ubiquitous and was milder than that seen in other forms of partial IFN-gammaR1 deficiency, accounting for the more severe clinical phenotype of the patient, which was almost as severe as that of patients with complete deficiency.
Assuntos
Códon de Iniciação , Mutação em Linhagem Germinativa , Infecções por Mycobacterium/genética , Receptores de Interferon/deficiência , Receptores de Interferon/genética , Linfócitos B/metabolismo , Linhagem Celular , Células Cultivadas , Criança , Feminino , Fibroblastos/metabolismo , Predisposição Genética para Doença , Humanos , Interferon gama/metabolismo , Mutação de Sentido Incorreto , Infecções por Mycobacterium/metabolismo , Infecções por Mycobacterium/microbiologia , Especificidade da Espécie , Receptor de Interferon gamaRESUMO
Interferon gamma receptor deficiency is a rare autosomal recessive inherited disorder, with poor prognosis due to early-onset, recurrent, and disseminated mycobacterial infections. Hematopoietic stem cell transplantation (HSCT), the only curative treatment, is particularly difficult in these patients owing to a high rate of graft rejection. We report the first successful hematopoietic stem cell transplantation with an unrelated donor, performed in a schoolgirl with severe interferon gamma receptor 1deficiency caused by a novel mutation.
