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: ["Gene"].

Please return the output as a JSON object of the format: {"Gene": ["SSX", ...]}. 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:

Gene-gene interaction between the monoamine oxidase A gene and solute carrier family 6 (neurotransmitter transporter, noradrenalin) member 2 gene in anorexia nervosa (restrictive subtype). We earlier found an association between anorexia nervosa (AN) restrictive subtype (AN-R) and an inserted sequence within the NETpPR, a polymorphic region located in the promoter of the solute carrier family 6 (neurotransmitter transporter, noradrenalin) member 2 (SLC6A2) gene. To further examine the noradrenergic system in AN-R we performed an association study with a functional polymorphism (MAOA-uVNTR) in the promoter of the monoamine oxidase A (MAOA) gene. Since monoamine oxidase A metabolises noradrenalin, a positive association with the MAOA gene would be biologically plausible. The transmission disequilibrium test and 95 trios/duos (AN-R females+biological parents) showed the main effect of the longer, more transcriptionally active form of the MAOA-uVNTR (MAOA-L) to be statistically non-significant (McNemar's chi(2)=1.4, df=1, P=0.238, odds ratio: 1.4, 95% CI 0.8-2.7). A case-control approach supported this finding. We then stratified the MAOA-uVNTR TDT data according to the (a) NETpPR genotype of the AN-R females, and (b) NETpPR allele transmitted from NETpPR-S4/L4 heterozygous mothers. In both cases, contingency table analysis revealed previously unreported gene-gene interaction between the MAOA and SLC6A2 genes (P=0.019 and 0.019, respectively). Receiving an MAOA-L allele more than doubles the risk for developing AN-R, conditional on an individual also being a NETpPR-L4 homozygote (stratum-specific odds ratio: 2.4, 95% CI 1.1-6.0). These results suggest important involvement of the noradrenergic system in the biological underpinnings of AN-R.
{"Gene": ["MAOA", "TDT", "SLC6A2", "monoamine oxidase A", "solute carrier family 6 (neurotransmitter transporter, noradrenalin) member 2"]}