Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The two isotypes of the fourth complement component are C4A and C4B. C4B forms ester bonds more efficiently than C4A and so, in theory, is more likely than C4A to bind to polysaccharide capsules of encapsulated bacteria. Two studies have reported homozygous C4B deficiency in patients with meningitis or bacteremia caused by encapsulated organisms. In the present study the association between C4B deficiency and these disorders was evaluated in four groups: patients with bacteremia, those with meningitis, those who developed Haemophilus influenzae type b (Hib) disease after Hib polysaccharide vaccination, and patients less than 1 year old with meningitis. Healthy adults served as controls. Of the 257 patients, 2.3% had homozygous C4B deficiency compared with 3.7% of 349 controls. According to these data, there is no increase in homozygous C4B deficiency among patients with bacteremia or meningitis caused by encapsulated bacteria.
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PMID:C4B deficiency is not associated with meningitis or bacteremia with encapsulated bacteria. 156 46

The fourth component of complement (C4) is crucial to the activation of the classical complement pathway, a key defense against invading microorganisms. The two isotypes of C4, C4A and C4B, have very different in vitro activities. An increased incidence of total C4B deficiency was found in white patients with Streptococcus pneumoniae, Haemophilus influenzae, or Neisseria meningitidis infection (14% of bacteremic children vs. 2% of race-matched controls, P = .02). In black patients, however, there was no difference in incidence of C4B deficiency between bacteremic patients and race-matched controls (7% and 5%, respectively, P greater than .5). These data suggest that, at least in whites, total C4B deficiency is a risk factor for invasive disease with these three encapsulated organisms.
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PMID:C4B deficiency: a risk factor for bacteremia with encapsulated organisms. 235 98