Complement system disorders

Which of the following is TRUE regarding paroxysmal nocturnal hemoglobinuria?

1: It is due to a mutation of the PIG-A gene, resulting in impaired complement activation
2: It is due to impaired production of glycosylphosphatidylinositol-linked membrane proteins
3: Serum LDH and haptoglobin levels will be low
4: The classic symptom of dark urine tends to occur late in the day because completent is more active during daytime hours.