You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Variant", "Disease", "Species", "CellLine", "Chemical", "Gene"].

Please return the output as a JSON object of the format: {"CellLine": ["hRPTEC", ...], "Chemical": ["Glucose", ...], "Disease": ["Diabetes", ...], "Gene": ["HNF-6", ...], "Species": ["Patients", ...], "Variant": ["Pro75Ala", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Lack of association of C-C chemokine receptor 5 DD32 deletion status with rheumatoid arthritis, systemic lupus erythematosus, lupus nephritis, and disease severity. OBJECTIVE: C-C chemokine receptor 5 (CCR5) plays an important role in inflammation. A 32 base-pair (DD32) deletion in the CCR5 gene leads to a nonfunctional receptor. This deletion has been reported to have a protective effect on the development and progression of several autoimmune diseases. We investigated whether the DD32 deletion is associated with disease susceptibility in a population of patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and lupus nephritis (LN); and whether it is associated with disease severity. METHODS: DNA samples from 405 RA patients, 97 SLE patients, 113 LN patients, and 431 healthy controls were genotyped for the CCR5 DD32 deletion. Differences in genotype frequencies were tested between patients and controls. Association of genotypes with disease severity was analyzed. RESULTS: Genotype frequencies of each group were in Hardy-Weinberg equilibrium. The genotype frequencies of patients did not differ significantly from controls (CCR5/DD32, DD32/DD32: RA 18.3% and 1.2%, respectively; SLE 17.5% and 2.1%; LN 13.3% and 1.8%; controls 20.0% and 2.8%). However, there was a trend for lower DD32 deletion allele frequency in LN patients compared to controls (p = 0.08). There was no significant association between the CCR5 status and disease severity in RA, SLE, or LN. CONCLUSION: Although an association with LN cannot be excluded, the CCR5 DD32 deletion does not seem to be a disease susceptibility genotype for RA, SLE, or LN. No significant effect of the DD32 deletion on disease severity was demonstrated.
{"CellLine": [], "Chemical": [], "Disease": ["lupus nephritis", "inflammation", "LN", "rheumatoid arthritis", "autoimmune diseases", "systemic lupus erythematosus", "RA", "SLE"], "Gene": ["CCR5", "C-C chemokine receptor 5"], "Species": ["patients"], "Variant": ["DD32", "DD32 deletion", "32 base-pair (DD32) deletion"]}