NSMCE2 and microcephalic primordial dwarfism: Interestingly, the clinical phenotype exhibited by patients with variants in the SMC5/6 complex components NSMCE2 and NSMCE3 are different from each other, with the former being associated with microcephalic primordial dwarfism and insulin resistance20 and the latter being associated with severe pulmonary disease and immunodeficiency18,19.