FNIP1-associated syndrome (MONDO_0100432) can be described as follows. Any immunodeficiency in which the cause of the disease is a mutation in the FNIP1 gene. Disruption of Folliculin Interacting Protein 1 alters the essential metabolic regulators AMPK and mTOR, resulting in profound B-cell deficiency, hypertrophic cardiomyopathy, and pre-excitation syndrome. Also known as: FNIP1 deficiency, absent B cells, agammaglobulinemia, and hypertrophic cardiomyopathy syndrome, immunodeficiency with cardiomyopathy and pre-excitation syndrome.