fault, shortcoming, desert, flaw, blemish, defective, abnormality, deficiency, malfunction, irregularity, more...

perfection, excellence, strength, virtue, quality

birth defect, chromosomal defect, genetic defect, physical defect, mental defect, more...

septal, congenital, serious, mental, genetic, atrial, large, primary, physical, visual, basic

switch sides,   negative quality,   become a renegade,   switching sides,   leaving a faction,   problem with,   flaw for a recipe,   a fault,   material flaw,   change allegiance