A new study of complement factor I deficiency (2006)
- Authors:
- Autor USP: ISAAC, LOURDES - ICB
- Unidade: ICB
- Assunto: IMUNOLOGIA
- Language: Inglês
- Abstract: Introduction and Objectives: Factor (F) I is one of most important regulatory proteins and its absence causes a deregulation of the alternative pathway resulting in low levels of C3 and FB. This deficiency is responsible for severe and recurrent infections. A 14 year old Brazilian boy presented purpura since the age of 4 and 5 episodes of otitis.media. Our aim is to characterize and identify the mutations responsible for the lack of FI. Methods and Results: We analysed the concentration of several complement proteins in the sera of the patient and his family. The patient presented very low C3 levels, low levels of FB and FH and undetectable concentration of FI by radial immunodiffusion. The hemolytic activity mediated by the alternative pathway was absent in the proband's serum. The activity mediated by the classical pathway was below the limit of the method. His mother and sister presented low levels of FI, FB, C4 (only sister's serum), and FH but normal concentrations of C3 and normal activity mediated by classical and alternative pathways. The father presented normal FI and low FB and FH levels and his sera presented normal hemolytic activity mediated by both classical and alternative pathways. C3 was present in the father's serum at a concentration higher than normal.These results support a new case of FI deficiency responsible for low levels of C3 in the proband. In despite of low levels of FI, Western blot analysis allowed usto identify both FI heavy chain (50 kDa) and light chain (38 kDa) in correct sizes in the deficient serum. No differences were observed in the FI mRNA expression levels of the proband and controls. Most of the patient's FI cDNA was sequenced and so far only a new polymorphic substitution G514A was found which results in a Gly171Asp substitution in the SRCR domain. This region plays an important role in maintaining FI conformation, but cannot explain this deficiency since some normal controls also carry the same variation. Conclusion: A new case of FI deficiency is described in a Brazilian family. The molecular basis responsible for this deficiency is under investigation.
- Imprenta:
- Source:
- Título: Abstracts
- Conference titles: Meeting of the Brazilian Society for Immunology
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ABNT
VENDRAMINI, M I M et al. A new study of complement factor I deficiency. 2006, Anais.. São Paulo: Instituto de Ciências Biomédicas, Universidade de São Paulo, 2006. . Acesso em: 09 jan. 2026. -
APA
Vendramini, M. I. M., Rodrigues, V. H., Reis, E. S., Florido, M. P. C., Nudelman, V., Goldenberg, J., & Isaac, L. (2006). A new study of complement factor I deficiency. In Abstracts. São Paulo: Instituto de Ciências Biomédicas, Universidade de São Paulo. -
NLM
Vendramini MIM, Rodrigues VH, Reis ES, Florido MPC, Nudelman V, Goldenberg J, Isaac L. A new study of complement factor I deficiency. Abstracts. 2006 ;[citado 2026 jan. 09 ] -
Vancouver
Vendramini MIM, Rodrigues VH, Reis ES, Florido MPC, Nudelman V, Goldenberg J, Isaac L. A new study of complement factor I deficiency. Abstracts. 2006 ;[citado 2026 jan. 09 ] - Ligação de leptospira interrogans serovar pomona às diferentes variantes de fator H (TYR402 and HIS402)
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