Total C4B deficiency due to gene deletion and gene conversion in a patient with severe infections

Taina Jaatinen, Meri Lahti, Olli Ruuskanen, Riikka Kinos, Lennart Truedsson, Riitta Lahesmaa, Marja-Liisa Lokki

Research output: Contribution to journalArticlepeer-review

117 Downloads (Pure)


Deficiencies of the early components of the classical complement pathway impair the actions of innate and humoral immunity and may lead to increased susceptibility to infections. We have studied the genetic basis of total C4B deficiency in a Finnish patient with recurrent meningitis, chronic fistulas and abscesses. The maternal chromosome carried a four-gene deletion including the C4B gene, and a conversion from C4B to C4A gene was found on the paternal chromosome resulting in complete deficiency of C4B. In the converted C4A gene, mutation screening did not reveal any amino acid changes or prominent mutations, yet a large number of nucleotide variations were found. Further, the patient was heterozygous for structural deficiency of mannan binding lectin (MBL) associating with medium levels of serum MBL. Our data provides new information on the genetic instability of the C4 gene region, and on the association of homozygous C4B deficiency and variant MBL genotype with increased susceptibility to recurrent and chronic infections. Importantly, plasma therapy induced a prompt clinical cure with long-term effects.
Original languageEnglish
Pages (from-to)195-201
JournalClinical and Diagnostic Laboratory Immunology
Issue number2
Publication statusPublished - 2003

Subject classification (UKÄ)

  • Microbiology in the medical area
  • Immunology in the medical area


Dive into the research topics of 'Total C4B deficiency due to gene deletion and gene conversion in a patient with severe infections'. Together they form a unique fingerprint.

Cite this