IKZF2 and Osteopenia: Monoallelic germline defects of IKZF2 have been found to underlie immunodeficiencies and autoimmunity (with incomplete penetrance), and a biallelic IKZF2 missense variant was found to cause syndromic immunodeficiency with osteopenia and hypothyroidism (Hetemäki et al. 2021; Shahin et al. 2021, 2022).