In addition, Cyp21a1 encodes a hydroxylase expressed in the epithelium of the developing lung (Gilbert et al. 2017) and deficiencies in this hydroxylase result in congenital adrenal hyperplasia (El-Maouche et al. 2017), while the product of Tnxb is an extracellular matrix glycoprotein whose variants are associated with the connective tissue fragility of Ehlers–Danlos Syndrome (Chen et al. 2016; Mao et al. 2002). The gene discussed is TNXB; the disease is congenital adrenal hyperplasia.