Investigation of complement component C4 copy number variation in human longevity.
Genetic factors have been estimated to account for about 25% of the variation in an adult's life span. The complement component C4 with the isotypes C4A and C4B is an effector protein of the immune system, and differences in the overall C4 copy number or gene size (long C4L; short C4S) may influence the strength of the immune response and disease susceptibilities. Previously, an association between C4B copy number and life span was reported for Hungarians and Icelanders, where the C4B*Q0 genotype, which is defined by C4B gene deficiency, showed a decrease in frequency with age. Additionally, one of the studies indicated that a low C4B copy number might be a genetic trait that is manifested only in the presence of the environmental risk factor "smoking". These observations prompted us to investigate the role of the C4 alleles in our large German longevity sample (∼ 700 cases; 94-110 years and ∼ 900 younger controls). No significant differences in the number of C4A, C4B and C4S were detected. Besides, the C4B*Q0 carrier state did not decrease with age, irrespective of smoking as an interacting variable. However, for C4L*Q0 a significantly different carrier frequency was observed in the cases compared with controls (cases: 5.08%; controls: 9.12%; p = 0.003). In a replication sample of 714 German cases (91-108 years) and 890 controls this result was not replicated (p = 0.14) although a similar trend of decreased C4L*Q0 carrier frequency in cases was visible (cases: 7.84%; controls: 10.00%).
Institute of Clinical Molecular Biology, Christian-Albrechts-University of Kiel, Kiel, Germany.
Friederike
F
Flachsbart
Institute of Medical Informatics and Statistics, Christian-Albrechts-University of Kiel, Kiel, Germany.
Amke
A
Caliebe
Institute of Clinical Molecular Biology, Christian-Albrechts-University of Kiel, Kiel, Germany.
Femke-Anouska
FA
Heinsen
Norwegian PSC Research Center, Division of Cancer, Surgery and Transplantation, Oslo University Hospital, Rikshospitalet, Oslo, Norway ; Research Institute for Internal Medicine, Oslo University Hospital, Rikshospitalet, Oslo, Norway ; Section of Gastroenterology, Department of Transplantation Medicine, Division of Cancer, Surgery and Transplantation, Oslo University Hospital, Rikshospitalet, Oslo, Norway ; Division of Gastroenterology, Institute of Medicine, University of Bergen, Bergen, Norway.
Tom
T
Hemming-Karlsen
Institute of Clinical Molecular Biology, Christian-Albrechts-University of Kiel, Kiel, Germany ; Department of General Medicine, University Hospital Schleswig-Holstein, Kiel, Germany ; Popgen Biobank, Christian-Albrechts-University, Kiel, Germany.
Stefan
S
Schreiber
Institute of Clinical Molecular Biology, Christian-Albrechts-University of Kiel, Kiel, Germany.
Andre
A
Franke
Institute of Clinical Molecular Biology, Christian-Albrechts-University of Kiel, Kiel, Germany.
Almut
A
Nebel
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D003181:Complement C4 / Q000235:genetics*; D056915:DNA Copy Number Variations; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D005858:Germany; D006801:Humans; D008136:Longevity / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D055815:Young Adult
D003181:Complement C4