Figure 1.

Schematic representation of the XAI-AGE model. The gene-CpG layer receives input data in the form of CpG methylation beta values. From here on, the information propagates in a restricted manner where nodes in the later layers are connected only if they are annotated jointly with the given node in the current layer according to the ReactomeDB. From left to right, the model’s abstraction becomes progressively more complex, as later levels in the neural network correspond to higher levels in the hierarchy defined by the ReactomeDB. The prediction of the chronological age for any given sample is given by the arithmetic mean of the outputs obtained for each individual layer. As indicated, the input layer can be easily extended by any new modalities which can be represented on the level of genes³⁵.