Genetic studies report over 100 LOF and functionally heterogeneous variants (HGMD: https://www.hgmd.cf.ac.uk, accessed on 15 November 2023) in LPL (Table 1) associated with the development of LPL deficiency (MIM*609708) in subjects with FCS [38]. The gene discussed is LPL; the disease is hyperinsulinemic hypoglycemia, familial, 4.