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[Clinical findings and genetic bases of congenital complement deficiencies]
Insights
Late complement component deficiencies (LCCD) are common in Japan. C9 deficiency, while often asymptomatic, is linked to meningococcal meningitis, suggesting targeted complement testing for at-risk individuals.
Area of Science:
- Immunology
- Genetics
- Molecular Biology
Context:
- Inherited deficiencies in plasma complement components and control proteins.
- High prevalence of late complement component deficiencies (LCCD) in Japan.
- Focus on clinical manifestations of neisserial infections linked to LCCD.
Purpose:
- To review clinical findings and genetic bases of complement deficiencies.
- To detail clinical features of neisserial infections associated with LCCD in Japan.
- To investigate the association between C9 deficiency and specific diseases.
Summary:
- C9 deficiency is a frequent genetic disorder in Japan, with most individuals remaining healthy.
- C9 deficiency shows a significant association with meningococcal meningitis, but not systemic lupus erythematosus.
- The common Arg 95 Stop mutation in the C9 gene is prevalent, found in approximately 1 in 1000 homozygous and 1 in 15 heterozygous individuals.
Impact:
- Highlights the importance of complement studies, including C9 antigen and DNA analysis, in patients with meningococcal meningitis or recurrent bacterial infections.
- Provides insights into the molecular epidemiology of C9 deficiency in Japan.
- Informs clinical practice regarding the screening and management of individuals with complement deficiencies.
Abstract:
The clinical findings and genetic bases of inherited deficiencies of plasma complement components and complement control proteins are reviewed. In Japan, since the frequencies of late complement component deficiencies (LCCD) are high, clinical features of neisserial infections associated with LCCD are described in details. C 9 deficiency is one of the most frequent genetic disorders in Japan and most of them are healthy. However, C 9 deficiency is weakly but significantly associated with the development of meningococcal meningitis but not of systemic lupus erythematosus. The common Arg 95 Stop mutation was found in most individuals with C 9 deficiency. Molecular epidemiologic study revealed that homozygous and heterozygous Arg 95 Stop mutation of C 9 gene is found in approximately one of 1000 individuals and one of 15 individuals, respectively. Complement studies including C 9 antigen and DNA analyses should be performed in patients with meningococcal meningitis or recurrent bacterial infections.