Direct nucleotide sequencing of PCR-amplified exon IV of the patient-derived fibrinogen Bβ-chain gene. The DNA sample of PCR-amplified exon of patient’s fibrinogen Bβ-chain gene was subjected to urea-PAGE and subsequently to autoradiography. Part of the autoradiogram is shown. The arrow indicates the mutation of G for A at position 5121, coding Ser (TGA) for Asn (TAA) at position 160 of the fibrinogen β chain.