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Substitution of 'ARG POT.127' by 'HIS POT.127' in the regulatory complement protein factor H is associated to the its deficiency in a patient with concomitant lack of complement component C9

D A Falcão E S Reis; M T Amano; D Paixão-Cavalcante; M P C Florido; D Moraes-Vasconcelos; A S Grumach; Lourdes Isaac; Meeting of the Brazilian Society for Immunology (31. 2006 Búzios)

Abstracts São Paulo, SP: Brazilian Society for Immunology, 2006

São Paulo 2006

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  • Título:
    Substitution of 'ARG POT.127' by 'HIS POT.127' in the regulatory complement protein factor H is associated to the its deficiency in a patient with concomitant lack of complement component C9
  • Autor: D A Falcão
  • E S Reis; M T Amano; D Paixão-Cavalcante; M P C Florido; D Moraes-Vasconcelos; A S Grumach; Lourdes Isaac; Meeting of the Brazilian Society for Immunology (31. 2006 Búzios)
  • Assuntos: IMUNOLOGIA
  • É parte de: Abstracts São Paulo, SP: Brazilian Society for Immunology, 2006
  • Notas: Disponível em CD-ROM
  • Descrição: Introduction and Objectives: Complete Factor (f) H deficiency is rare. Only 22 cases have been described and little is known regarding its causes at the molecular level. C9 is a component of the membrane attack complex and its deficiency, while rare in Caucasians, is quite prevalent in Japanese. Our proband (6 years old boy) is Brazilian from a family of Japanese descent and history of consanguinity. He presents both C9 (C9D) and fH deficiencies. Here we characterize the clinical aspects and molecular basis of our probands' of both deficiencies. Methods and Results: The patient was referred with severe recurrent pneumonia. Radial immunodiffusion assays indicated low levels of fH (73 mg/mL), C3 (22 mg/mL) and fB (<57 mg/mL). His mother also had low levels of fH (76 mg/mL), C3 and fB, while his father and sister had low levels of fH, but normal levels of C3. Western blot assays showed the complete absence of the 150 kDa protein (fH) but the 43 kDa and 42 kDa bands which may include FHL-1 and FHR-1b and a 37 kDa band (FHR-1 a) were present. While C5-C8 components were present in relatively normal concentrations no C9 was detected in the proband's serum. Using Western blot only a very faint band was observed corresponding to the expected C9 size (~70kDa). This observation reduces the possibility of a premature stop codon as the cause of the C9D. RT-PCR followed by sequencing of the proband's fH cDNA revealed a homozygous G453A substitution,
    which results in an Arg to His127 mutation. This substitution is also homozygous in the mother and may alter fH protein tertiary structure and/or affect its secretion profile. PCR assays using proband's C9 genomic DNA fragments showed that he lacks the Arg95 mutation commonly observed in Japanese C9D. Conclusion: The proband has a complete absence of the fH protein but does present other proteins of fH family. He carries a missense mutation encoding a His127 instead of Arg127. This mutation may impair the fH secretion by the proband's cells. C9 is not completely absent but present in very low concentrations compared with normal control. The proband lacks the mutation responsible for C9D commonly observed in Japanese patients.
  • Editor: São Paulo
  • Data de criação/publicação: 2006
  • Formato: res. CL.062.
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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