Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving nucleic acid
Reexamination Certificate
1999-06-30
2001-07-31
Fredman, Jeffrey (Department: 1655)
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving nucleic acid
C435S091200, C536S022100, C536S023100, C536S025300, C514S012200
Reexamination Certificate
active
06268142
ABSTRACT:
1. BACKGROUND OF THE INVENTION
Genetics of the IL-1 Gene Cluster
The IL-1 gene cluster is on the long arm of chromosome 2 (2q13) and contains at least the genes for IL-1&agr; (IL-1A), IL-1&bgr; (IL-1B), and the IL-1 receptor antagonist (IL-1RN), within a region of 430 Kb (Nicklin, et al. (1994) Genomics, 19:382-4). The agonist molecules, IL-1&agr; and IL-1&bgr;, have potent pro-inflammatory activity and are at the head of many inflammatory cascades. Their actions, often via the induction of other cytokines such as IL-6 and IL-8, lead to activation and recruitment of leukocytes into damaged tissue, local production of vasoactive agents, fever response in the brain and hepatic acute phase response. All three IL-1 molecules bind to type I and to type II IL-1 receptors, but only the type I receptor transduces a signal to the interior of the cell. In contrast, the type II receptor is shed from the cell membrane and acts as a decoy receptor. The receptor antagonist and the type II receptor, therefore, are both anti-inflammatory in their actions.
Inappropriate production of IL-1 plays a central role in the pathology of many autoimmune and inflammatory diseases, including rheumatoid arthritis, inflammatory bowel disorder, psoriasis, and the like. In addition, there are stable inter-individual differences in the rates of production of IL-1, and some of this variation may be accounted for by genetic differences at IL-1 gene loci. Thus, the IL-1 genes are reasonable candidates for determining part of the genetic susceptibility to inflammatory diseases, most of which have a multifactorial etiology with a polygenic component.
Certain alleles from the IL-1 gene cluster are known to be associated with particular disease states. For example, IL-1RN (VNTR) allele 2 has been shown to be associated with osteoporosis (U.S. Pat. No. 5,698,399), nephropathy in diabetes mellitus (Blakemore, et al. (1996) Hum. Genet 97(3):369-74), alopecia areata (Cork, et al., (1995) J. Invest. Dermatol. 104(5 Supp.):15S-16S; Cork et al. (1 996) Dermatol Clin 14:671-8), Graves disease (Blakemore, et al. (1995) J. Clin. Endocrinol. 80(1):111-5), systemic lupus erythematosus (Blakemore, et al. (1994) Arthritis Rheum. 37:1380-85), lichen sclerosis (Clay, et al. (1994) Hum. Genet 94:407-10), and ulcerative colitis (Mansfield, et al. (1994) Gastoenterol. 106(3):637-42)).
In addition, the IL-1A allele 2 from marker −889 and IL-1B (TaqI) allele 2 from marker +3954 have been found to be associated with periodontal disease (U.S. Pat. No. 5,686,246; Kormman and diGiovine (1998) Ann Periodont 3:327-38; Hart and Kornman (1997) Periodontol 2000 14:202-15; Newman (1997) Compend Contin Educ Dent 18:881-4; Kornman et al. (1997) J. Clin Periodontol 24:72-77). The IL-1A allele 2 from marker −889 has also been found to be associated with juvenile chronic arthritis, particularly chronic iridocyclitis (McDowell, et al. (1995) Arthritis Rheum. 38:221-28). The IL-1B (TaqI) allele 2 from marker +3954 of IL-1B has also been found to be associated with psoriasis and insulin dependent diabetes in DR3/4 patients (di Giovine, et al. (1995) Cytokine 7:606; Pociot, et al. (1992) Eur J. Clin. Invest. 22:396-402). Additionally, the IL-1RN (VNTR) allele 1 has been found to be associated with diabetic retinopathy (see U.S. Ser. No. 09/037472, and PCT/GB97/02790). Furthermore allele 2 of IL-1RN (VNTR) has been found to be associated with ulcerative colitis in Caucasian populations from North America and Europe (Mansfield, J. et al., (1994) Gastroenterology 106:637-42). Interestingly, this association is particularly strong within populations of ethnically related Ashkenazi Jews (PCT W097/25445).
Genotype Screening
Traditional methods for the screening of heritable diseases have depended on either the identification of abnormal gene products (e.g., sickle cell anemia) or an abnormal phenotype (e.g., mental retardation). These methods are of limited utility for heritable diseases with late onset and no easily identifiable phenotypes such as, for example, vascular disease. With the development of simple and inexpensive genetic screening methodology, it is now possible to identify polymorphisms that indicate a propensity to develop disease, even when the disease is of polygenic origin. The number of diseases that can be screened by molecular biological methods continues to grow with increased understanding of the genetic basis of multifactorial disorders.
Genetic screening (also called genotyping or molecular screening), can be broadly defined as testing to determine if a patient has mutations (alleles or polymorphisms) that either cause a disease state or are “linked” to the mutation causing a disease state. Linkage refers to the phenomenon th DNA sequences which are close together in the genome have a tendency to be inherited together. Two sequences may be linked because of some selective advantage of co-inheritance. More typically, however, two pymorphic sequences are co-inherited because of the relative infrequency with which meiotic recombination events occur within the region between the two polymorphisms. The co-inherited polymorphic alleles are said to be in linkage disequilibrium with one another because, in a given human population, they tend to either both occur together or else not occur at all in any particular member of the population. Indeed, where multiple polymorphisms in a given chromosomal region are found to be in linkage disequilibrium with one another, they define a quasi-stable genetic “haplotype.” In contrast, recombination events occurring between two polymorphic loci cause them to become separated onto distinct homologous chromosomes. If meiotic recombination between two physically linked polymorphisms occurs frequently enough, the two polymorphisms will appear to segregate independently and are said to be in linkage equilibrium.
While the frequency of meiotic recombination between two markers is generally proportional to the physical distance between them on the chromosome, the occurrence of “hot spots” as well as regions of repressed chromosomal recombination can result in discrepancies between the physical and recombinational distance between two markers. Thus, in certain chromosomal regions, multiple polymorphic loci spanning a broad chromosomal domain may be in linkage disequilibrium with one another, and thereby define a broad-spanning genetic haplotype. Furthermore, where a disease-causing mutation is found within or in linkage with this haplotype, one or more polymorphic alleles of the haplotype can be used as a diagnostic or prognostic indicator of the likelihood of developing the disease. This association between otherwise benign polymorphisms and a disease-causing polymorphism occurs if the disease mutation arose in the recent past, so that sufficient time has not elapsed for equilibrium to be achieved through recombination events. Therefore identification of a human haplotype which spans or is linked to a disease-causing mutational change, serves as a predictive measure of an individual's likelihood of having inherited that disease-causing mutation. Importantly, such prognostic or diagnostic procedures can be utilized without necessitating the identification and isolation of the actual disease-causing lesion. This is significant because the precise determination of the molecular defect involved in a disease process can be difficult and laborious, especially in the case of multifactorial diseases such as inflammatory disorders.
Indeed, the statistical correlation between an inflammatory disorder and an IL-1 polymorphism does not necessarily indicate that the polymorphism directly causes the disorder. Rather the correlated polymorphism may be a benign allelic variant which is linked to (i.e. in linkage disequilibrium with) a disorderausing mutation which has occurred in the recent human evolutionary past, so that sufficient time has not elapsed for equilibrium to be achieved through recombination events in the intervening chromosomal segment. Thus, for the purposes of diagnostic and prognosti
Camp Nicola Jane
Cox Angela
di Giovine Francesco S.
Duff Gordon W.
Arnold Beth E.
Chakrabarti Arun
Foley Hoag & Eliot
Fredman Jeffrey
Interleukin Genetics Inc.
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