They found that iPSCs derived from patients with mild forms of AAT deficiency with no outward disease symptoms were able to degrade and secrete the immature/misfolded proteins relatively efficiently, whereas in severe mutations the AAT was degraded slowly and its immature form was localized to pre-Golgi compartments, resulting in aggregation and aberration of cellular function and morphology (91). The gene discussed is SERPINA1; the disease is alpha 1-antitrypsin deficiency.