SDS-PAGE of reduced fibrinogen from index subject (I) and normal control (N). Aα- or Bβ-chain fragments were identified through N-terminal sequencing. Intact Aα- or Bβ-chain bands are seen in the normal control, but not the index subject. N-terminal sequence of each band is as follows: 24 kDa, ADSGEGDFLA; 25 kDa, ADSGEGDFLA; 38 kDa, DNENVVNEYS; 50 kDa, ARPAKAAATQ.