The complement system is composed of more than 25 different proteins and is usually divided into classical and alternative pathways. Complement component 7(C7) is one of the five terminal complement proteins that, upon activation of either the classical or the alternative pathway, interacts sequentially to form a large protein-protein complex, called membrane attack complex(MAC). Assembly of the MAC on target cells results in the formation of transmembrane pores that can lead to the killing of the cells. C7 deficiency is an autosomal recessive disorder that is mostly reported in Caucasians. The gene for C7 has been assigned to chromosome 5p13. To date, 15 different molecular defects leading to total or subtotal C7 deficient defects have been reported. C7 deficiency is associated frequently with recurrently bacterial infections, especially meningitis caused by Neisseria meningitidis. We report a case of a hereditary C7 deficiency associated with meningococcal meningitis.
Bacterial Infections ; Complement C7 ; Complement System Proteins ; Homicide ; Membranes ; Meningitis ; Meningitis, Meningococcal* ; Neisseria meningitidis

Complement component 7 (C7) deficiency leads to the loss of complement lytic function, and affected patients show increased susceptibility to encapsulated organisms infection, especially Neisseria meningitidis. Recently, we have experienced a 20-year-old military trainee with meningococcal sepsis and meningitis who was diagnosed as having C7 deficiency based upon the undetectable serum C7 protein on radioimmunoassay. This case emphasizes that although C7 deficiency is rare immune disorder, it is important to be aware of possibility about late complement deficiency among patients who present with meningococcal disease.
Complement C7 ; Complement System Proteins ; Humans ; Immune System Diseases ; Immunologic Deficiency Syndromes ; Meningitis ; Military Personnel ; Neisseria meningitidis ; Radioimmunoassay ; Sepsis

Meningococcal infections can be associated with abnormalities of the complement system, which contains 5 terminal complement proteins. Furthermore, deficiencies in 1 of these 5, complement component 7 (C7), leads to the loss of complement lytic function, and affected patients show increased susceptibility to recurrent meningococcal meningitis and systemic Neisseria gonorrhoeae infection. In September 2003, an 11-year-old female patient presented at our outpatient department with high fever, lower leg pain, headache, and petechiaes. She rapidly progressed to coma but later achieved full recovery due to prompt treatment. Her final diagnosis was meningococcal sepsis and arthritis. Her elder brother also had a similar bacterial meningoencephalitis history, which encouraged us to perform analyses for complement component and gene mutations. Resultantly, both the brother and sister were found to have the same mutation in the C7 gene. Subsequently, vaccinations of the meningococcal vaccine meningococcal vaccine (Menomune(R)) were administered. However, in September 2006, the brother expired due to acute micrococcus meningoencephalitis. At present, the 16-year-old female patient is healthy. Here, we report a Korean family with a hereditary C7 deficiency with susceptibility to meningococcal infections due to C7 gene mutation.
Adolescent ; Arthritis ; Child ; Coma ; Complement C7 ; Complement System Proteins ; Female ; Fever ; Headache ; Humans ; Immunologic Deficiency Syndromes ; Leg ; Meningitis, Meningococcal ; Meningococcal Infections ; Meningococcal Vaccines ; Meningoencephalitis ; Micrococcus ; Neisseria gonorrhoeae ; Outpatients ; Sepsis ; Siblings ; Vaccination