No evidence for linkage in the promoter region of the inducible nitric oxide synthase gene (NOS2) in a Danish type 1 diabetes population.
Exposure of human pancreatic islets to a mixture of cytokines induces expression of inducible nitric oxide synthase (iNOS), impairs beta-cell function and induces apoptosis. Exposing human islets to high amounts of NO from chemical NO-donors causes DNA strand breaks and mitochondrial damage, suggesting that NO is deleterious to human beta-cells. Hence, we consider the gene encoding iNOS in beta-cells, NOS2, a candidate gene for type 1 diabetes in humans. In the present study we have tested three identified polymorphisms within the promoter sequence of the human NOS2 gene in a type 1 diabetic family material comprising 154 affected sib-pair families and 103 affected simplex families (1143 individuals in total). PCR-based amplification of the polymorphic loci were established. Linkage analysis was performed using the extended transmission disequilibrium testing (ETDT). A Bsal RFLP was found not to be polymorphic in 20 type 1 diabetic patients and 14 healthy control subjects and was not analysed further. In affected cases a nine allele CCTTT repeat and a bi-allelic TAAA repeat revealed allelewise Petdt of 0.52 and 0.60, respectively. ETDT applied to (TAAA)n; (CCTTT)n haplotypes demonstrated random transmission from heterozygous parents to affected offspring. In conclusion, the tested polymorphisms within the NOS2 gene promoter did not show evidence for linkage to type 1 diabetes in a Danish family material.
Johannesen
J
J
Steno Diabetes Center, Niels Steensensvej 2, DK-2820 Gentofte, Denmark.
Pociot
F
F
Kristiansen
O P
OP
Karlsen
A E
AE
Nerup
J
J
D001483:Base Sequence; D016022:Case-Control Studies; D017931:DNA Primers / Q000235:genetics; D003718:Denmark; D003922:Diabetes Mellitus, Type 1 / Q000201:enzymology* / Q000235:genetics*; D005260:Female; D008040:Genetic Linkage; D006239:Haplotypes; D006801:Humans; D015810:Linkage Disequilibrium; D008297:Male; D018895:Microsatellite Repeats; D019001:Nitric Oxide Synthase / Q000235:genetics*; D052247:Nitric Oxide Synthase Type II; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012150:Polymorphism, Restriction Fragment Length; D011401:Promoter Regions, Genetic
D017931:DNA Primers; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II