PENK and hyperinsulinemic hypoglycemia, familial, 4: Unsupervised dimensionality-reduction using UMAP (uniform manifold approximation and projection) algorithm on flow cytometry data (Supplementary Fig. 4) shows that penk-deficiency resulted in a slight but significant increase in the frequency of CD4+ T lymphocytes associated with a reduction of those of some innate immune cell subsets, including macrophages/dendritic cells, type-1 innate lymphoid cells and mast cells (Fig. 2).